ferrite measurement in austenitic and duplex stainless steel castings
TRANSCRIPT
Literature Review
Ferrite Measurement in Austenitic and DuplexStainless Steel Castings
Submitted to:SFSA/CMC~OE
August 1999
Submitted by:C. D. LundinW. Ruprecht
G. Zhou
Materials Joining Research GroupDepartment of ‘Materials Science and Engineering
The Universityof Tennessee,Knoxville
.
. . ~ .. .... . .. 7..,, . . . . . . ,.. ... . . . . . . . . . . . . . . . . . . . . . J...,:.-- .— . . . . . .
DISCLAIMER
This report was prepared as an account of work sponsoredby an agency of the United States Government. Neither theUnited States Government nor any agency thereof, nor anyof their employees, make any warranty, express or implied,or assumes any legal liability or responsibility for theaccuracy, completeness, or usefulness of any information,apparatus, product, or process disclosed, or represents thatits use would not infringe privately owned rights. Referenceherein to any specific commercial product, process, orservice by trade name, trademark, manufacturer, orotherwise does not necessarily constitute or imply itsendorsement, recommendation, or favoring by the UnitedStates Government or any agency thereof. The views andopinions of authors expressed herein do not necessarilystate or reflect those of the United States Government orany agency thereof.
.=— ~,..— , , > .. -,.., ,..,,.,.., . ......-....,,. .. . -r.m.-.m=- . . . -.-=— —— -—--r —— ---–-- ——-— .--–-—..-
.
DISCLAIMER
Portions of this document may be illegibfein electronic image products. Images areproduced from the best available originaldocument.
..- . . ..-. --..—- -. —— -- -.-—. — .-. ..—.. —-
—,----7> . . . .. . , ... , .L-7-=m r.,.,-,
\
. .. . . . .... . . ., . . . .. ... . . . ., { . . ,,- . . ,.. < . .. —..._.—. .. ____
TABLE OF CONTENTS
PAGE
1.0 PROGRAM INTRODUCTION ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . .... 1
2.0 PROJECT GOALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . .... 3
3.0 LITERATURE REVIEW .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . .... . . . . .4
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . 4
3.1.1 Impofimce to Indus@ ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..."""""""""" 43.1.2 Advances in Ferrite Measurement .. . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . .5
3.2 Review of Measurement Techniques .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . 10
3.2.1 Metallographic Point Counting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... 12
3.2.2 Constitution Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . 13
3.2.2.1 Schaeffler Diagram . .. . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . . . . ... . . . . . . . ... . . . . . 14
3.2.2.2 DeLong Diagram . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . ... . . . . . 14
3.2.2.3 WRC 1988 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . ... . .... 17
3.2.2.4 WRC 1992 Diagram . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . ... . . . . .... 20
3.2.3 Magnetic Ins~entation .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . .."..2O3.2.3.1 Magnetic Indicators (e.g.. Severe Gage) . . . . . . . . . . . .... . . . . .... . . . . ... . ...233.2.3.2 Attractive Force (e.g., Magne Gage) .. . . . . . . . . . . . . .... . . . . . .. . . . . .... . . . . . 24
3.2.3.3 Magnetic Permeability (e.g., Feritscope@) . ..... . . . . . . . ... . . . . .... . ... . .. 26
3.3 Literature Review - Conclusions .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . ... . . . . .. 29
4.0 REFERENCES .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . ... . . . . .31
5.0 BIBLIOGRAPHY .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..'......34
6.0 SPECIFICATIONS .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... . . . . . . . . . . .... . ... 39
7.0 APPENDIX .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... . . . . . . . . . . . . . ...40
-+- ,, -,‘;. ,,.., ,. /, . .,,f.,., $- .1.,.>,. .- ‘, .-. ., ,.s..-. ,> ,,..., .,,,...- /, .,,- ,.: .... :.---- —.—— ... . . ..__..-,<
1.0 PROGRAM INTRODUCTION
Ferrite measurement techniques evolved after the realization that austenitic
stainless steel weld metals, containing a moderate amount of ferrite, were free of hot
cracking related weld defects. Ferrite measurement was immediately identified as a
method by which engineers could quantifi the amount of weld metal ferrite and ensure
that their fabrications would be free from hot cracking. The advent of duplex stainless
steels further re-emphasized the need for adequate ferrite measurement techniques as a
suitable ferrite/austenite phase balance provides adequate mechanical properties and
improved corrosion performance. In order to qualify their cast products, reliable means
to measure ferrite were developed to assure compliance with industrial practices and
customer requirements.
The Ferrite Measurement program was conceived with the ideology that an
increased database, with regard to current ferrite measurement techniques, will benefit
producers and users of stainless steel castings. Utilizing available instrumentation, a
series of “round-robin” tests have been implemented to study lab-to-lab variation in
traditional magnetic and modern electronic ferrite measurement techniques. Since the
implementation of this program (February 1998), the Materials Joining Research Group
(University of Tennessee – Knoxville) conducted a survey of literature and initiated
studies into the characterization of castings. Studies involving ferrite content
measurement as a function of surface roughness were designed. Efforts to characterize
ferrite content as a function of depth from the surface of a casting were implemented.
1
Additionally, this research effort has moved toward the development of a practice to
manufacture cast secondary standards, which are required for the calibration of electronic
ferrite measurement equipment.
This increased knowledge base has a direct impact upon industrial corporations
that manufacture duplex stainless steel castings. Analysis of ferrite ~pically requires a
more time consuming and possibly destructive analysis in which castings are sectioned
for metallographic analysis or resized to complement an instrument. With the validation
of improved techniques, the amount of expended labor and energy usage can decrease
while productivity can improve. It is the desire of this research effort that a marked
reduction in energy usage and associated material and labor costs shall result from an
increased understanding of new ferrite determination techniques and their applicability to
industry.
2
2.0 PROJECT GOALS
The following project goals have been defined for this program:
● Comparison of metallographic, magnetic and electronic permeability methods of
ferrite measurement and assessment of statistical repeatability for each method.
● Examination of variations in ferrite content by performing surface-to-core depth
profile measurements on castings.
● Examination of the effect of surface finish on measurement capability.
● Development of standard ferrite measurement procedures.
● Development of a methodology for the production of Cast Secondary Standards.
● Publication of research and guidance in ferrite measurement.
3.0 LITERATURE REVIEW
3.1 Introduction
A critical review of published literature has been conducted to define methods of
ferrite measurement and means of round-robin testing for measurement validation.
Special attention has been paid to relevant technical specifications (AWS A4.2) as well as
research articles. This review is primarily concentrated on applicable ferrite
measurement techniques and their inherent capability and accuracy. The following
section, “Importance to Industry”, describes the desire of industrial producers and users
of stainless steel castings to obtain repeatable and cost effective methods of ferrite
determinations for their finished products.
3.1.1 Importance to Industry
Producers and users of stainless steel castings have recognized the need to
accurately quanti~ the microstructure of their finished product. With increasing demand
being placed upon quality and reliability by institutions like the International
Standardization Organization (ISO 9000/ ISO 9001), engineers have recently become
concerned with their ability to accurately quanti.fj the ferrite content in a casting, and
thus to veri~ the capability of their manufacturing processes. Additionally, efforts to
4
eliminate destructive evaluation, as a method to qualifi castings, have yielded to new
developments in ferrite measurement techniques.
With the advent of new technology for non-destructive evaluations of ferrite
content, new options have been introduced to foundries, consumers and engineers. Prior
to examining current techniques, a review of “Advances in Ferrite Measurement” was
compiled from a series of Adam’s Lectures presented at the American Welding Society’s
annual meetings and then subsequently published in the Welding Journal.
3.1.2 Advances in Ferrite Measurement
In his 1974 Adams Lecture, W.T. DeLong summarized the subject of ferrite
measurement for the 55* annual American Welding Society (AWS) Meeting. During his
lecture, DeLong recounted the characteristics of ferrite and its importance in the field of
welding. Dating his lecture material prior to World War II, DeLong was able to
characterize early observations of the effect of ferrite on cracking, fissuring, mechanical
properties and corrosion performance of weldments.l
As a part of his lecture, DeLong recounted methods of ferrite measurement
including calculation of ferrite from chemistry, metallography, magnetic measurement, x-
ray diffraction and magnetic permeability. His critique of each available method, as
applied to weld metal substrates consisting of austenitic stainless steels, revealed the
following observations:2
● Ferrite determination from chemistry had been evaluated and was considered a
statistically viable option for ferrite prediction through the application of
5
appropriate constitution diagrams. The Schaeffler and DeLong diagrams were the
only applicable diagrams which incorporated alloy chemistry into ferrite content
prediction.
● The statistical accuracy of metallographic measurements (point counting) was
highly influenced by the ferrite colony size, and the introduction of automated
techniques had done little to improve upon operator variances. It was also
observed that changes in ferrite content within the same substrate made
quantification representative of the entire sample difficult.
● Magnetic measurements, using commercially available instruments, were defined
to be a suitable method of quantifying ferrite content. Such devices are discussed
fiu-ther in this review.
● The use of x-ray diffraction as a ferrite measurement technique was applicable.
However, diffraction patterns were diffuse in nature and subject to interpretation.
It was concluded that sufllcient accuracy was unattainable using this technique.
● Magnetic permeability measurements had not yet been accurately researched.
Although proposals had been submitted on this subject, insufficient research had
been conducted to validate such a technique.*
*Note: Future developments would later validate this method of ferritemeasurement.
Incorporating these techniques into a world-wide round-robin test series, the
International Institute of Welding (IIW), Subcornmission IIC and the Advisory
6
,... ~ ~ .-,... . . . . . ......../<. t a.,’,.:,; .,. .~: (.:.. >3, + . . . . :..-. ,. .,>, w.. ,...- . . ,,<,, .,,+,-,. ___
Subcommittee of the High Alloys Commitiee of the Welding Research Council (WRC),
initiated two doctrines in 1974. They are presented as follows:
1) Based upon the round-robin test series, the WRC Advisory Subcommittee proposed
that the term “Ferrite Number” (FN) replace conventional “percent ferrite” as a
method to quantifi ferrite content. The lack of appropriate universal calibration
procedures and reference standards had produced significant lack of agreement
between laboratories. At that time, FN was meant to directly replace “percent ferrite”
on a 1:1 basis.3
Note: Future research would reveal that the 1:1 correlation of FN to “volume percentferrite” is only acceptable for low ferrite contents (0-10 FN), such as that presentin the majority of austenitic stainless steel weld metals. The application of ferritemeasurement techniques to duplex stainless steels would require fin-ther testing todefine appropriate correlations.
2) The lack of standardized testing methods produced significant variability in the data
acquired from IIW round-robin testing. Furthermore, measurements between
laboratories suggested that further work was required to institute a universal system
of ferrite measurement.4
Data from IIW round-robin testing enabled the WRC to establish a standard
practice for quantifying ferrite content using available techniques. The publication of
AWS A4.2, “Standard Procedures for Calibrating Magnetic Instruments to Measure the
Delta Ferrite Content of Austenitic Stainless Steel WeId Metal”, was the among the first
steps to provide a universal calibration procedure for magnetic instrumentation.
Developments in ferrite measurement techniques continued for the next 20 years
before another review of applicable techniques was performed. In that time, the FN
7
system was explored through a series of round robin test series and AWS A4.2 undertook
a series of revisions to incorporate newly developed techniques.
Dr. D. J. Kotecki revisited the topic of ferrite measurement in his 1997 article
entitled, “Ferrite Determination in Stainless Steel Welds – Advances since 1974”
(Reference 23). Describing the revisions to AWS A4.2 and recounting research efforts
encompassing the previous 20 years, the following items were highlighted:
. Extension of the Ferrite Number {FNl Svstem:
With the advent of new stainless steel alloys (duplex), the need to characterize
materials, whose ferrite content exceeded 28 FN, was established.5 The FN system
was studied with various modifications, including extrapolation, calibration with new
coating thickness standards and the development of cast secondary standards.*
**Note: Coating thickness standards (primary standards) and cast secondatystandards will be examined in following sections of this review.
. Ferrite Number vs. Ferrite Percent:
The relationship between ferrite number and ferrite percent was explored utilizing
weId metal samples. However, it was determined that the morphology and
distribution of weld metal ferrite promoted unwanted effects during metallographic
characterization. Such effects included a lack of agreement between laboratories,
utilizing metallographic techniques, due to the fineness and irregular morphology of
weld metal ferrite.
However, such adverse morphologies were not present in cast materials. In
general, the ferrite size was significantly coarser and more regularly shaped than weld
8
metal ferrite. A comparison of point counting and magnetic measurements revealed
that the ratio of ferrite number to ferrite percent was not uniform over the entire FN
scale. It was established that the correlation was roughly 1:1 for FN values of O-28.
However, above 28 FN the correlation deviated. Examinations, during experimental
trials, suggested that this correlation could be approximated using a ferrite number to
ferrite percent ratio of 1.4:1. However, a lack of agreement between laboratories left
this issue in dispute among researchers.b
● Future Work:
Dr. Kotecki suggested that the issue of “ferrite number vs. ferrite percent” needed
Iirther study. However, his suggestions indicated that the lack of agreement between
laboratories, to establish a firm correlation, did not preclude the successful use of the
FN system.
It was apparent that the only universal baseline to evaluate castings and
weldments was a direct determination of the amount of ferrite present. This fiuther
necessitated the need for a correlation between ferrite number and ferrite volume percent.
It was also suggested that current ferrite measurement techniques were not applicable for
the characterization of heat-affected zones in comparison to the unaffected base metal or
weld metal. Due to the relatively narrow width of the heat-affected zone, no available
technique had been able to adequately characterize this region. Although specifications
required a destructive metallographic examination to determine the ferrite content of the
heat-affected zone, this specification was not accepted due to a lack of reproducibility
within the same weldment. It was concluded that a new breed of technology of ferrite
9
measurement techniques needed to be developed to combat this situation. Finally, the
constitution diagrams commonly used to predict the ferrite content based upon alloy
chemistry required further development to allow for additional alloying elements and
variations in cooling rate due to different joining processes.’
Having clearly defined the past, present and fi.dureresearch efforts regarding
ferrite measurement techniques, it was evident that this area had undergone a significant
amount of change and investigation since its conception in the 1940’s. The current
review concentrates on defining each appropriate ferrite measurement technique, paying
careful attention to evaluate its efficacy.
~ .2 Review of Measurement Techniques
A variety of techniques have been developed to determine the amount of ferrite
present in a substrate. Ferrite measurement has been performed using the following
techniques:
●
●
●
●
●
●
●
Metallographic Point Counting
Constitution Diagrams
Magnetic Attraction
X-Ray Diffraction
Mossbauer Effect
Magnetic Permeability
Magnetic Saturation
10
Among the above techniques, x-ray diffraction and the Mossbauer effect have
been applied to only laborato~ experimentation. The principles governing x-ray
diffraction and interpretation of diffraction spectra have long been characterized,
however, the Mossbauer effect suggested interesting new principles.
L. J. Schwartzendruber discussed the Mossbauer effect in 1974 in a Welding
Journal Research Supplement article entitled “Mossbauer – Effect Examination of Ferrite
in Stainless Steel Welds and Castings”.* When applied to alloy systems, it was found that
different phases within a metal yield differing Mossbauer spectra. It was also found that
the relative areas contained within the spectra were directly proportional to the amount of
each phase present.g In comparing this techniques with others, Schwartzendruber
commented that the Mossbauer technique was a valid method to conduct ferrite
measurement. However, its application was limited to laboratory testing and cannot be
readily utilized in the field.
Measurement by magnetic saturation involved saturating a given interaction
volume with a magnetic field and measuring the associated magnetic response. K.
Bungart (et al.) discovered that such measurements were highly influenced by alloy
chemistry and the chemical composition of the ferrite. It was found that the saturation
magnetism of the ferrite was governed by its chemistry. 10 Therefore, accurate ferrite
measurements could ordy be obtained if the saturation magnetism of ferrite was
established as a function of chemical composition. This technique has not been
developed for commercial use. These principles were also examined as a part of
Schwartzendruber’s examination of the Mossbauer effect.
11
~.,~.,.;y-~.--T--T---- --,
.—. —.._.
Having defined the less common ferrite measurement techniques, emphasis is
now placed upon the use of metallographic point counting, constitution diagrams and
magnetic instrumentation as viable methods of ferrite measurement.
3.2.1 Metallographic Point Counting
ASTM E562 is the “Standard Practice for Determining Volume Fraction by
Systematic Manual Point Count.” This specification may be applied to any
microconstituent or phase which is metallographically identifiable. The principles
governing this method are clearly defined in the specification. A two-dimensional
metallographic sample is prepared and examined at an appropriate magnification. A grid
is then superimposed over the image and the operator counts the number of points which
fall within the desired phase or microconstituent. Statistical analysis reveals the fraction
of points which fall within the desired phase and the volume fraction is then calculated. 11
When correctly implemented, this technique is an excellent method for determining the
volume fraction of a desired phase or microconstituent. However, accuracy is often
influenced by many factors, including the following:
Homogenei~
Quality of Sample Preparation
Grid Densi~
Magnification of the Substrate
Operator Interpretation of the Microstructure
12
Attempts to mechanize this technique, using computer software, often decreased
analysis time but still required the use of a trained technician. Although accurate, this
technique requires a significant amount of preparation and analysis time. Preparation
includes metallographic polishing to a 0.05 micron finish and the application of a suitable
etching technique. Etching techniques are tailored to a specific microconstituent.
AdditionalIy, this technique is destructive in nature, requiring that a sample be extracted
from the component or substrate. It was also Iimited to the number of fields examined
and the location of the removed sample.
Because metallographic point counting is a destructive test and requires extensive
preparation and analysis time, significant effort is placed upon the development of
techniques which were non-destructive and labor eftlcient. Scientists and engineers next
placed their focus on the effect of alloy chemistry on the amount of ferrite present.
3.2.2 Constitution Diagrams
Schaeffler, DeLong and WRC constitution diagrams introduced a non-destructive
method to relate alloy composition to the amount of ferrite present in an alloy. The
development of such a technique eliminated the need to destructively analyze a
component, given that an accurate chemical analysis could be performed.
13
3.2.2.1 SchaefflerDiagrarn
The introduction of the Schaeffler diagram (1949) provided the first method to
calculate ferrite percent in a non-destructive manner. Schaeffler mathematically
correlated chromium and nickel equivalents, which were readily calculated based upon
the alloy chemistry, to the amount of ferrite present. Based upon the amount of nickel,
carbon, manganese, chromium, molybdenum, silicon and niobium (columbium) present,
a brief reference to this diagram quickly estimated the amount of ferrite present (Figure
1).’3
C. J. Long and W. T. DeLong cited the inherent problem of nitrogen additions
during welding in their 1973 article entitled “The Ferrite Content of Austenitic Stainless
Steel Weld Metal” (Reference 35). Although DeLong had published his own constitution
diagram, accounting for nitrogen levels in weld metal, he identified an inherent problem
associated with Schaeffler’s diagram. Ferrite content varied with the amount of nitrogen
present. As Schaeffler had not addressed this issue, nitrogen levels became a source of
experimental error to be addressed in the next generation of constitution diagrams. 14
3.2.2.2 DeLong Diagram
W. T. DeLong (et. al.)15revised the Schaeffler diagram in 1956 by adding the
effect of nitrogen to the nickel equivalent. Citing a weighting factor of 30 for the effect
of nitrogen, DeLong proposed a significant relationship between nitrogen concentration
and ferrite formation (Figure 2).
14
32
28
24 ‘/NIst enite
z
;. 20 I \ //1/
.-Z /Y/II 12 I II \ I x/Y
/
4 /
F M+F\ Ferrite
+ AOIM \ I K 1- I I 1 ,
0 4 8 12 16 20 24 28 32 3640
Crw=Cr+ Mo+l.5x Si+0.5x Nb
Figure 1. Schaeffler Diagram
From ASM Specialty Handbook@ on Stainless Steels, edited by J. R.
Davis, Copyright 1994.
15
,.-,, .,! ->, .-.. . 7 ----- ----7=-~-m..., , ,, ,, . s<< .. .. . s 7- ----- 7,7 .-+. . ..f. .,. .,,- —_:. T_. -= —--—.—— . -- .....-...’- .
16 17 18 192021222224 252627
Crq=Cr+Mo+ l.5x Si+0.5x Nb
Figure 2. DeLong Diagram
From ASM Specialty Handbook@ on Stainless Steels,
edited by J. R. Davis, Copyright 1994.
16
The major advantage of the DeLong diagram was its introduction of nitrogen as a
significant factor in ferrite formation. Nitrogen, an austenitizer, retards the formation of
ferrite. DeLong postulated that variations in welding technique and atmospheric
conditions could affect the nitrogen content in weld metal, thus affecting the amount of
ferrite formed during solidification of the weld pool. His work increased the accuracy of
the Schaeffler diagram and revealed that his estimations predicted increased ferrite over
that of Schaeffler, for a given chemistry.~c
3.2.2.3 WRC 1988 Diagram
In 1988, T. A. Siewert, C. N. McCowan and D. L. Olson published the WRC 1988
constitution diagram (Reference 49). This diagram accounted for the following flaws in
the Schaeffler and DeLong diagrams:
●
●
17
The DeLong diagram is essentially a finely tuned subset of the Schaeffer range,
designed specifically for the 300-series stainless steel welds containing small amounts
of ferrite. 17 The refined nature of the DeLong diagram forced engineers to reference
the Schaeftler diagrams for alloys containing more than 15% ferrite. As previously
defined, the Schaeffler diagram did not have the improved degree of accuracy or
accountability for nitrogen that the DeLong diagram developed.
The effect of manganese on ferrite formation had been incorrectly established. An
improved database revealed that the original 0.5 weighting factor should have been
changed to unity (l), based upon work performed by E. R. Szurnachowski and D. J.
Kotecki.18
. A study by R. H. Espy revealed that the effect of nitrogen on ferrite formation
resulted in a decreased value of the nitrogen coefficient in the nickel equivalent.
Espy suggested that the nitrogen coefficient be lowered from 30 to 20.19
. The effect of silicon on weld metal ferrite had been examined by D. J. Kotecki. The
results of his study revealed that the 1.5 silicon weighting factor used in both the
Schaeffler and DeLong diagrams was inaccurate. Kotecki’s work suggested that the
weighting factor be reduced to O.12012]Kotecki conducted a similar study to
investigate the effect of molybdenum and concluded that its coefficient be reduced
from 1.0 to 0.7.22
Siewert, McCowan and Olson concluded that, based upon the studies of elemental
effects on ferrite formation, there was significant need to develop anew constitution
diagram for the prediction of weld metal ferrite content. The WRC 1988 diagram (Figure
3) was then developed according to the following goals:23
Development of a database containing recent FN data and new compositions.
Evaluation of the accuracy of the Schaeffler and DeLong diagrams.
— Determination of which elements were not properly incorporated in these diagrams.
— Development of an improved predictive diagram that was continuous over the range
of o-1oo FN.
The development of the NRC 1988 diagram improved the applicable ferrite
range, reestablished the appropriate manganese, molybdenum, nitrogen and silicon
contents, improved accuracy over the DeLong and Schaeffler diagrams and included
solidification boundaries that correspond to changes in FN response.24
18
/.- ;7: _k- .,7. - — ~.=-=.,. . . . . ,,., . . . . .7,,.+. ::. . W,’44;RY ,77 > “ -., . . ..- .-,. l/Y6,., -. .-4. . . . -...-..;
—. —.-. — _., ,.+~ :>.i-,— — :.. .!, ..
““*T : .--Y-7, - . . . . ... .. .. . . . . /.< ,,>,- . . .. .,:+! .,.. . . ,. .... -=-?7 . . . -r.:-i.,-..,-.. ,.-,. , +>,.,. ,:...&._.__— ——_.. .— . .._
Figure 3. WRC 1988 Diagram
From ASM Specialty Handbook@ on Stainless Steels,
edited by J. R. Davis, Copyright 1994.
19
3.2.2.4 WRC 1992 Diagram
Shortly after the submission of the WRC 1988 diagram, D; J. Kotecki and T. A.
Siewert sought to include the effect of copper on the formation of ferrite in duplex
stainless steels. While developing the WRC 1988 diagram, a copper coefficient was
considered. However, research had not provided sufficient agreement on a universal
value. Therefore, as the demand for duplex stainless steels increased, a need was
recognized to modi~ the existing WRC diagram to include the effects of copper on the
chromium equivalent.25
The resulting WRC 1992 (Figure 4) constitution diagram presented increased
accuracy and the ability to extend the chromium and nickel equivalences to allow
dilution calculations incorporating dissimilar base matetials and electrode compositions.
As a result of the advent of this diagram, engineers were able to rely on increased
accuracy in ferrite prediction for copper-bearing alloys. Alloys with residual copper
contents were not adversely affected. Additionally, this diagram allowed for the
accountability of dissimilar weld joint conilgurations, which was a luxury not afforded by
previous constitution diagrams.2G
3.2.3 Magnetic Instrumentation
The use of x-ray difiaction, Mossbauer techniques and magnetic saturation as
methods of ferrite measurement were previously described. Experimental
20
,,
-. ;,,, ,-c,?j~., ,,,.., ., ; ; ,,f,.<$7--,7 . .. .,,. .— -.,,, , . .. .,,,. /—~.f -,. :---’Wm. , - ,, ... .,,,.,----T2?W%K-71T . ...
.-—. —,. =. /-.?+:.2 ~,-:, ...-?TZZ ~——————— —..-——
10
17
16
15
14
13
~ 12
30 11
~ 10
~:
z~7z
26
5
4
3
2
1
001 23456 78910111213141S16 17181920212223242526 2728293031
Crq. Cr + Mo + 0.7Nb
Figure 4. WRC 1992 Diagram
From ASM Specialty Handbook@ on Stainless Steels, edited by J.
R. Davis, Copyright 1994.
21
- ,.-.-:r; ,.- -.-<-my- , ...r.---—.m .. .. , .../ ...>.../:., ..... .,.. , =-T.y. T--- - .. . .. . . /, .-.., *.— -— ~..=..—. -. —.—
trials revealed that these practices would not be readily applied to field engineering
situations due to the use of laboratory conilned equipment or variations in material
response to each technique. However, as previously indicated, developments in magnetic
instrumentation proved usefil in creating reliable, reproducible and user-fi-iendly ferrite
measurement equipment. In the following sections, magnetic indicators, attractive force
indicators and magnetic permeability instruments are introduced as viable methods for
quanti~ing fenite content.
The measurement of ferrite content yielding reproducible results was addressed‘
separately by E. Stalmasek, E.W. Pickering, E.S. Robitz and D. M. Vandergriff.
Stalmasek investigated the “Measurement of Ferrite Content in Austenitic Stainless Steel
Weld Metal Giving Internationally Reproducible Results” (Reference 52) while
Pickering, Robitz and Vandergriff concentrated on “Factors Influencing the Measurement
of Ferrite Content in Austenitic Stainless Steel Weld Metal Using Magnetic Instruments”
(Reference 39). Both articles are contained within Welding Research Council Bulletin
318 (Reference 53). WRC Bulletin318 is addressed in the following paragraphs as
individual magnetic measurement devices are described.
The following items were identified as significant to the development of new
ferrite measurement devices by the above authors. 27
● Ferrite chemistry, distribution, particle shape/size, and degree of transformation were
identified as factors which make precise and accurate ferrite measurement difficult.
● The utilization of different measuring techniques does not necessarily yield identical
results.
22
~,r . . . ..-l — .+, -l~.~> ,, .> m.-.mz- .. ,.. .......!, .Zmm,....,- ..,. .- — -TV--T---- -—----
●
●
●
Sample size and shape must be considered such that its geometry does not affect
ferrite measurement due to unwanted edge effects.
Reproducibility between instruments required the institution of a standard calibration
procedure to incorporate all techniques.
The relationship between ferrite number and ferrite percent is non-linear.
For additional information describing the ferromagnetic properties of ferrite in a duplex
microstructure, refer to reference 52.
3.2.3.1 Magnetic Indicators (e.g., Severn Gage)
Having identified ferrite as a ferromagnetic phase, the first efforts to construct a
device to assess ferrite content included magnetic indicators. Utilizing a permanent bar
magnet, suspended from a lever arm, the substrate ferrite content was compared to a
reference magnet. The reference magnet was either a permanent magnet or
electromagnet.
R. B. Gun.iaand G. A. Ratz reviewed the petiormance of such devices in WRC
Research Bulletin 132 (August 1968). Gunia and Ratz differentiated between
instruments utilizing a permanent reference magnet (Severe Gage, Tinsley Gage and
Elcometer) and those using an electromagnetic reference magnet (Ferrite Tester, Magne-
Probe, Magnetoscope and Perrnascope)?8
The advantage associated with such devices included ease of use and portability.
With the inclusion of reference magnets of varying strength and associated ferrite
23
content, the user was able to quickly determine a range over which the ferrite content of
the subject was contained. This technique eliminated the need for laborious
metallography and time consuming analysis. However, the degree to which the ferrite
content range could be characterized was governed by the reference magnets. Thus, this
technique was only a “quick and dirty” estimation of the substrate ferrite content. No
calibration of the instrument was required beyond establishing the ferrite content of the
reference magnets.
3.2.3.2 Attractive Force (e.g., Magne Gage)
Building on the characteristics of the magnetic indicators, a device was sought
which could directly correlate the force required to separate a magnet from a substrate
(tear-off force) to the ferrite content of the substrate. The governing principle was that
increasing ferrite content would promote a larger ferromagnetic response, which would
result in increasing force required to separate a reference magnet from a substrate.
However, no such device existed for that specific purpose.
While Schaeffler was developing his constitution diagram, a device had been
constructed to measure the thickness of nonmagnetic coatings on magnetic materials.
The principles governing the Magne Gage were easily defined. A permanent magnet,
suspended from a lever arm, would be lowered until the magnet was in contact with the
substrate. Using a calibrated dial, increasing torque was applied, through a helic~ spring,
until the reference magnet separated from the substrate. The dial reading was recorded
and compared to a calibration curve, which revealed the coating thickness or ferrite
24
-m . ..r7--w—.rr?——?.———.— --7-e--.’ YYe,..x>,-.-. .,. . . -T .....=.=.. ..=% .... . ,... ...-v -.= -—. —.-. ..-+ . ..— ,.—. . . . . ,
content.zg When properly calibrated, the Magne Gage proved to be a usefhl tool in
assessing ferrite content.30
The advantage of the Magne Gage was its capability of directly measuring the
ferrite content based upon magnetic response. The operator was no longer limited to a
range of possible ferrite contents, as described with the use of the Severn gage. Rather,
calibration to coating thickness standards (primary standards) allowed the operator to
directly assess the ferrite content as a function of ferrite number. Conversely, the Magne
Gage was primarily a laboratory instrument and was sensitive to outside vibrations. The
Magne Gage and the primary coating thickness standards are shown in subsequent
figures.
Use of the Magne Gage was revised in 1982 by D. J. Kotecki when he proposed
the extension of the WRC ferrite number system. Increasing use of duplex stainless steel
alloys required that the existing ferrite number system be expanded to include ferrite
contents above 28 FN. This new system covered the full range of duplex alloys up to
fully ferritic material. The new extended ferrite number (EFN) system proved to be
statistically viable, as compared to the original ferrite number system.31
The use of the Magne Gage increased in later years as scientists and engineers
. sought to determine the relationship between ferrite content and as-welded mechanical
properties. Studies by D. J. Kotecki32 and D. L. 01son33further validated the Magne
Gage as a usefid tool in characterizing the ferrite content of austenitic and duplex alloys.
Increased use of Magne Gages spurred the implementation of the IIW 5thRound
Robin of FN Measurements to assess interlaboratory variations in ferrite measurement.
The results showed suitable repeatability with proper calibration.3J
25
3.2.3.3 Magnetic Permeability (e.g.: Feritscope@)
Magnetic permeability has been defined as the ratio of magnetic induction to
magnetic field strength. Ferrite measurement, using this technique, required that a
magnetic field be induced on a substrate and the resulting field strength be measured to
establish the magnetic permeability.35 This technique, provided by Gunia and Ratz, was
later confirmed by E. Stalmasek in WRC Bulletin 318. Stalmasek fiuther commented
that “the overall perineability of a two phase alloy containing one ferromagnetic and one
nonferromagnetic phase, depends, at a given strength of the magnetizing fiel~ upon the
individual permeability, upon the content and upon demagnetization factor of the
ferromagnetic phase’’.36 In short, this established that the strength of the induced field
varied with the amount of ferromagnetic phase present.
The Fischer Feritscope@ was developed as a hand-held device which utilized
magnetic permeability as a method to assess ferrite content. As depicted in Figure 5, the
Feritscope@ was designed to be portable and provide the operator with a user-friendly
interface which readily provides ferrite content on the ferrite number scale.
Calibration of the Feritscope@ has been performed using cast secondary standards. Cast
secondary standards (Figure 6) were developed by NPO CNIIT-MASH (Russia) and
produced by Mladis Co. (Russia) under organizational support of the Russian Welding
Society. Each set of standards was produced from centrifugally chill cast rings and were
distributed to TIVI.37 Cast secondary standards were used exclusively to calibrate
Feritscopes@, but may also be used in the calibration of Magne Gages. The volume of
26
~:. -; T z~-y-~.--’-y,n ?, . . . . . . . . .,,:,MJ,.. %..., . ,.y, , T-, . . w,+”. .,- .777 I . ,, : ,: ,,..:.<XZ ---- ~7- — .
Figure 5.
Magne Gage
Magne-Gage and Fischer Feritscope@.
.. ,.
Feritscope@
27
,,“ ~ -’=”-~”, --7-– -–.?.W=-2- ~ ; . Az$ %- .,:-s.- ... ...- —- —.~.-~.— —,- —— ~——— —-—... , .... -j>.,..
. .. . . . .... ... . . -t
Figure 6.
Primary Standards
Primary and Cast Secondary Standards
28
Cast Secondary Standards
ferrite in each standard was controlled through modi&ing the alloy content, such that a
fill range of ferrite numbers is attainable.
Additional round robin testing was initiated by D. J. Kotecki, in conjunction with
IIW, to assess the reproducibility of Feritscopes@ when calibrated using cast secondary
standards. An interlaboratory variability of +14°/0was established. This value was
slightly higher than the variability established for Magne Gages (tl 0°/0)in previous
round robin test series .38
The advantages associated with the advent of the Feritscope@ included increased ~
operator efilciency and portability of the device. However, there has not been a
significant research effort to characterize the service performance of this gage when
applied to a multitude of conditions. Such conditions include analyzing the measurement
probe’s response to varying surface finishes, surface discontinuities and gage
repeatability. As the manufacturer does not currently provide such a database, a study to
clarify these operating variabIes has been introduced as apart of this research effort.
3.3 Literature Review - Conclusions
The IIW has remained invoIved in the implementation of additional round robin
testing to Iiuther characterize factors which affect ferrite measurement. Such factors
include, but are not limited to, the following:
. Substrate Surface Finish
. Measurement Probe Interaction Volumes
● Correlation between Ferrite Number and Ferrite Volume Percent
29
~,.-,-. ,’“‘- :“.:I?T,, .- . . ;.. --7.- -+-,,. <f . .%,. .’ ? .,>:+2.. ,, ::+. :J - --n,...,. ,, ~ . >..... ...,..-J,, : - ,, ,x, .
. .-., x-. :, . . ---
. Reliability and Repeatabili~ of Available Tectiques
Although it has been established that significant accomplishments have been
made in the field of ferrite measurement, it remains the belief of researchers and
engineers that additional testing, to explore the limitations of current techniques, is
required to further develop accurate and repeatable methods of ferrite measurement.
30
4.0 REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
DeLong, W.T. 1974, “Ferrite in Austenitic Stainless Steel Weld Metal”, WeldingJournal 53(7): 276-s
Ibid, 280-s
Ibid, 281-s
Ibid, 281-s
Kotecki, D.J., “Ferrite Determination in Stainless Steel Welds – Advances since1974”, Welding Journal, Vol. 76(l), ISSN: 0043-2296, 1997, 27-s to 34-s
Ibid, 35-s to 36-s
Ibid, 36-s
Schwartzendruber, L,J., Bennet, L.H., Schoefer, E.A., DeLong, W.T., andCampbell, H.C. 1974, “Mossbauer Effect Examination of Ferrite in StainlessSteel Welds and Castings”, Welding Journal 53(l), 2-s
Ibid, 3-s
10. Bungart, K., Dietrich, H., and Arntz, H., “The Magnetic Determination of Ferritein Austenitic Materials, and Especially in Austenitic Welded Material”, DEW-Techn. Ber. 10, p. 298, 1970
11. Schwartzendruber, L.J., Bermet, L.H., Schoefer, E.A., DeLong, W.T., andCampbell, H.C. 1974, “Mossbauer Effect Examination of Femite in StainlessSteel Welds and Castings”, Welding Journal 53(l), 9-s
12. ASTM E562, “Practice for Determining Volume Fraction by Systematic ManualPoint Count”, ASTM International, West Conshohocken, Pennsylvania, USA,1997
13. Schaeffler, A.L. 1949, “Constitution Diagram for Stainless Steel Weld Metal”,Metal Progress 56(1 1): 680-680B
14. Long, C.J. and DeLong, W.T. 1973, “The Ferrite Content of Austenitic StainlessSteel Weld Metal”, Welding Journal 52(7), 281-s to 297-s
31
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
DeLong, W., Ostrom, G., and Szumachowski, E. 1956, “Measurement andCalculation of Ferrite in Stainless Steel Weld Metal”, Welding Journal 35(11),521-s to 528-s
Long, C.J.and DeLong, W.T. 1973,’’The Fetite Content of Austenitic StainlessSteel Weld Metal”, Welding Journal 52(7), p. 283-s
Siewert, T.A., McCowan, C.N., and Olson, D.L. 1988, “Ferrite NumberPrediction to 100 FN in Stainless Steel Weld Metal”, Welding Journal 67(12):290-s
Szumachowski, E.R., and Kotecki, D.J. 1984, “Effect of manganese on StainlessSteel Weld Metal Ferrite”, Welding Journal 63(5), 156-s to 161-s
Espy, R.H. 1982, “Weldability of Nitrogen-Strengthened Stainless Steels”,Welding Journal 61(5), 149-s to 156-s
Kotecki, D.J. 1986, “Silicon Effect on Stainless Weld Metal Ferrite”, IIW. Dec.II-C-779-86, The American Council of the International Institute of Welding,Miami, F1.
Siewert, T.A., McCowan, C.N., and Olson, D.L. 1988, “Ferrite NumberPrediction to 100 FN in Stainless Steel Weld Metal”, Welding Journal 67(12):290-s
Kotecki, D.J. 1983, “Molybdenum Effect on Stainless Steel Weld Metal Ferrite”,IIW Document 11-C-707-83
Siewert, T.A., McCowan, C.N., and Olson, D.L. 1988, “Ferrite NumberPrediction to 100 FN in Stainless Steel Weld Metal”, Welding Journal 67(12):290-s
Ibid, 297-s
Kotecki, D.J. and Siewert, T.A., “WRC-1992 Constitution Diagram for StainlessSteeI Weld Metals: A Modification of the WRC 1988 Diagram”, WeldingJournal, May 1992, Vol. 71, pp. 171-s –172-s
Ibid, 178-s
WRC Bulletin 318, Welding Research Council, New York, USA
Gunia, R.B., and Ratz, G.A., “The Measurement of Delta—Ferrite in AusteniticStainless Steels”, WRC Bulletin 132, New York, N.Y, August 1968, p. 4.
32
29.
30.
31.
3~.
33.
34.
35.
36.
37.
38.
Stalmasek, 1986, WRC Bulletin 318, Welding Research Council, New York,USA, pp. 23-98
Gunia, R.B., and Ratz, G.A., “The Measurement of Delta—Femite in AusteniticStainless Steels”, WRC Bulletin 132, New York, N.Y, August 1968, p. 3. ‘-
Kotecki, D.J. 1982, “Extension of the WRC Ferrite Number System”, WeldingJournal 61(11): 352-s to 361-s
Kotecki, D.J., “Ferrite Control in Duplex Stainless Steel Weld Metal”, WeldingJournal, October 1986, Vol. 65(10), pp. 273-s to 278-s
Olson, D.L. 1985, “Prediction of Austenitic Weld Metal Microstructure andProperties”, Welding Journal 64(10): 281s to 295s
Rabensteiner, G., 1993, “Summary of 5* Round Robin of FN Measurements”,IIW Document 11-C-902-92, International Institute of Welding.
Gunia, R.B., and Ratz, G.A., “The Measurement of Delta—Ferrite in AusteniticStainless Steels”, WRC Bulletin 132, New York, N.Y, August 1968, p. 5.
Stalmasek, 1986, WRC Bulletin 318, Welding Research Council, New York,USA, p. 39
Ginn, B.J., Gooch, T.G., Kotecki, D.J., Rabensteiner, G. and Merinov, P., “WeldMetal Ferrite Standards Handle Calibration of Magnetic Instruments”, WeldingJournal, pp. 59-64
Kotecki, D.J. 1995, “IIW Commission II Round Robin of FN Measurements –Calibration by Secondary Standards”, IIW Document 11-C-043-95, InternationalInstitute of Welding
33
5.0 BIBL1OGRAPHY
1.
‘7-.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Aubrey, L.S., Wieser, P.F., Pollard, W.J. and Schoefer, E.A., “FerriteMeasurement and Control in Cast DupIex Stainless Steels”, Stainless SteelCastings, ASTM STP 756, V.G. Behal and A.S. Melilli, Eds., American Socie&for Testing and Materials, 1982, pp. 126-164
Blumfield, Dl, Clark, G.A. and Guha, P. 1981, “Welding Duplex Austenitic-Ferritic Stainless Steel”, MetaI Construction (5): 269-273
Brantsma, L.H., and Nijhof, P., 1986, “Ferrite Measurements: An Evaluation ofmethods and experiences”, International Conference on Duplex Stainless Steel,Paper 45, Nederlands Instituut voor Lastechniek, The Hague
Bryhan, A.J. and Poznasky, A. 1984, “Evaluation of the Weldability of ES2205”,Report CP-280, AMAX Metals Group, Ann Arbor, Michigan
Bungart, K., Dietrich, H., and Arntz, H., “The Magnetic Determination of Ferritein Austenitic Materials, and Especially in Austenitic Welded Material”, DEW-Techn. Ber. 10, p. 298,1970
Davis, J.R., “ASM Specialty Handbook - Stainless Steels”, ASM IntemationaI,Materials Park OH, 1994
DeLong, W., Ostrom, G., and Szurnachowski, E. 1956, “Measurement andCalculation of Ferrite in Stainless Steel Weld Metal”, Welding Journal 35(11),52 1-s to 528-s
DeLong, W.T., and Reid, Jr., H.F. 1957, “Properties of Austenitic Chromium inAustenitic Chromium-Manganese Stainless Steel Weld Metal”, Welding Journal,36(l), 41-s to 48-s
DeLong, W.T. 1974, “Ferrite in Austen.itic Stainless Steel Weld Metal”, WeldingJournal 53(7): 273-s to 286-s
Dijkstra, F.H., and de Raad, J.A., “Non-destructive Testing of Duplex Welds”,Duplex Stainless Steels 97 – 5* World Conference Proceedings, Stainless SteelWorld, @1997 KCI Publishing
Elmer, J.W., and Eagar, T.W., 1990, “Measuring the residual fetite content ofrapidly solidified stainless steel alloys”, Welding Journal 69(4), pp. 141-s to 150-s
Espy, R.H. 1982, “Weldability of Nitrogen-Strengthened Stainless SteeIs”,Welding Journal 61(5), 149-s to 156-s
34
.-.,.T-. , 7--,—, . , ., ,, ,’.- —
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
Farrar, J.C.M., Marshall, A.W., Zhang, Z., “A Comparison of Predicted andmeasured Ferrite Levels in Duplex and Super-Duplex Weld Metal”, DupIexStainless Steels 97 – 5thWorld Cotierence Proceedings, Stainless Steel World,@l 997 KCI Publishing
Ginn, B.J., Gooch, T.G., Kotecki, D.J., Rabensteiner, G. and Merinov, P., “WeldMetal Ferrite Standards Handle Calibration of Magnetic Instruments”, Welding -Journal, pp. 59-64
Gunia, R.B., and Ratz, G.A., “The Measurement of Delta—Ferrite in AusteniticStainless Steels”, WRC Bulletin 132, New York, N.Y, August 1968.
Gunia, R.B., and Ratz, G.A., “How Accurate are Methods for MeasuringFerrite?”, Metals Progress, p. 76, Jan. 1969
Gunn, R.N., “Duplex Stainless Steels – Microstructure, properties andapplications”, Abington Publishing, Cambridge England, 1997
Hull, F.C. 1973, “Delta Ferrite and Martensite Formation in Stainless Steels”,Welding Journal 52(5): 193-s to 203-s
International Standards Organization (1S0) Draft, “Standard Practice for theEstimation of Ferrite Content in Austenitic Stainless Steel Castings”, 1995
Kotecki, D.J., 1984, Progress Report Correlating Extended Ferrite Numbers withNBS Coating Thickness Standards”, IIW Document H-C-730-84, InternationalInstitute of Welding
Kotecki, D.J. 1982, “Extension of the WRC Ferrite Number System”, WeldingJournal 61(11): 352-s to 361-s
Kotecki, D.J., “Ferrite Control in Duplex Stainless Steel Weld Metal”, WeldingJournal, October 1986, Vol. 65(10), pp. 273-s to 278-s
Kotecki, D.J., “Ferrite Determination in Stainless Steel Welds – Advances since1974”, Welding Journal, Vol. 76(l), ISSN: 0043-2296, 1997, p.24-s
Kotecki, D.J. 1995, “HW Commission II Round Robin of FN Measurements –Calibration by Secondary Standards”, IIW Document H-C-043-95, InternationalInstitute of Welding
Kotecki, D.J. 1998, “FN Measurement Round Robin Using Shop and FieldInstruments After Calibration by Secondary Standards – Final Summary Reporf’,IIW Document 11-C-1405-98, International Institute of Welding
35
26,
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
Kotecki, D.J. 1990, “Ferrite Measurement and Control in Duplex Stairdess SteelWelds”, Weldability of Materials – Proceedings of the Materials WeldabilitySymposium, October, ASM International, Materials Park, Ohio.
Kotecki, D.J., “Ferrite Measurement in Duplex Stainless Welds”, DuplexStainless Steels 97 – 5thWorld Cotierence Proceedings, Stainless Steel World,@1997 KCI Publishing
Kotecki, D.J. 1983, “Molybdenum Effect on Stainless Steel Weld Metal Ferrite”,IIW Document 11-C-707-83
Kotecki, D.J. 1986, “Silicon Effect on Stainless Weld Metal Ferrite”, IIW. Dec.II-C-779-86, The American Council of the International Institute of Welding,Miami, F1.
Kotecki, D.J., 1995, “Standards and industrial methods for ferrite measurement”,Welding in the World 36, pp. 161-169
Kotecki, D.J. 1988, “Verification of the NBS-CSM Ferrite Diagram”,International Institute of Welding Document II-C-834-88
Kotecki, D.J. and Siewert,T.A.,“WRC-1992 Constitution Diagram for StainlessSteel Weld Metals: A Modification of the WRC 1988 Diagram”, WeldingJoumal, May 1992, Vol. 71, pp. 171-s –178-s
Lake, F.B. 1990, “Effect of Cu on Stainless Steel Weld Metal Ferrite Content”,Paper presented at AWS Annual Meeting
Leger, M.T., “Predicting and Evaluating Ferrite Content in Austenitic StainlessSteel Castings”, Stainless Steel Castings, ASTM STP 756, V.G. Behal and A.S.Melilli, Eds., American Society for Testing and Materials, 1982, pp. 105-125
Long, C.J. and DeLong, W.T. 1973, “The Ferrite Content of Austenitic StainlessSteel Weld Metal”, Welding Journal 52(7), 281-s to 297-s
Merinov, P., Entin, E., Beketov, B. and Runov, A. 1978, (February), “Themagnetic testing of the ferrite content of austenitic stainless steel weld metal”,NDT International, pp.9-14
McCowan, C.N. and Siewert, T.A. and Olson, D.L. 1989, “Stainless Steel WeldMetal: Prediction of Ferrite Content”, WRC Bulletin 342, Welding ResearchCouncil, New York, N.Y.
Olson, D.L. 1985, “Prediction of Austenitic Weld Metal Microstructure andProperties”, Welding Journal 64(10): 281s to 295s
36
.. , .-5 .x v. 77+-.. ‘y-,, , -., ... ...+ . ——. —..— ____ __. ._.. -
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
Pickering, E.W., Robitz, E.S. and Vandergriff, D.M., 1986, “Factors influencingthe measurement of ferrite content in austenitic stainless steel weld metal usingmagnetic instruments”, WRC Bulletin 318, Welding Research Council, NewYork, USA, pp. 1-22.
Potak, M. and Sagalevich, E.A. 1972, “Structural Diagram for Stainless Steels asApplied to Cast Metal and Metal Deposited during Welding”, Avt. Svarka (5): 10-13
Pryce, L. and Andrews, K.W. 1960, “Practical Estimation of compositionBalance and Ferrite Content in Stainless Steels”, Journal of Iron and SteelInstitute, 195:415,417
Rabensteiner, G., 1993, “Summary of 5ti Round Robin of FN Measurements”,IIW Document 11-C-902-92, International Institute of Welding.
Redmond, J.D. and Davison, R.M., 1997, “Critical Review of Testing MethodsApplied to Duplex Stainless Steels”, Duplex Stainless Steels 97 – 5thWorldConference Proceedings, Stainless Steel World, 01997 KCI Publishing
Reid, Harry F. and DeLong, William T. “Making Sense out of FerriteRequirements in Welding Stainless Steels”, Metals Progress, June 1973, pp. 73-77
Rosendahl, C-H, “Ferrite in Austenitic Stainless Steel Weld Metal; Round RobinTesting Programme 1971-1972”, HW Dec. II-631-72
Schaeffler, A.L. 1949, “Constitution Diagram for Stainless Steel Weld Metal”,Metal Progress 56(1 1): 680-680B
Schwartzendruber, L.J., Bermet, L.H., Schoefer, E.A., DeLong, W.T., and “Campbell, H.C. 1974, “Mossbauer Effect Examination of Ferrite in StainlessSteel Welds and Castings”, Welding Journal 53(l), 1-s to 12-s
Szumachowski, E.R., and Kotecki, D.J. 1984, “Effect of manganese on StainlessSteel Weld Metal Ferrite”, Welding Journal 63(5), 156-s to 161-s *Could be64(5)
Siewert, T.A., McCowan, C.N., and Olson, D.L. 1988, “Ferrite NumberPrediction to 100 FN in Stainless Steel Weld Metal”, Welding Journal 67(12):289-s to 298-s
Simpkinson, T.V., “Ferrite in Austenitic Steels Estimated Accurately~’ Iron Age,170, pp. 166-169, 1952
37
51. Simpkinson, T.V., and Lavigne, M.J., “Detection of Ferrite by its Magnetism,”Metal Progress, Vol. 55, pp. 164-167,1949
52. Stalmasek, E., “Measurement of Ferrite Content in Austenitic Stainless SteelWeld Metal giving Internationally Reproducible Results”, International Instituteof Welding Document II-C-595-79
53. Stalmasek, 1986, WRC Bulletin 318, Welding Research Council, New York,USA, pp. 23-98
54. Thomas, Jr., R.D. 1949, “A Constitution Diagram Application to Stainless WeldMetal”, Schweizer Archiv fhr Angewandte Wissenschaft und Technik, No. 1,3-24
55. Zhang, Z., Marshall, A.W. and Farrar, J.C.M., 1996, IIW Dec. 11-1295-96
38
6.0
1.
2.
3.
4.
5.
6.
7.
8.
SPECIFICATIONS
ANSI/AWSA4.2-91, “Standard Procedures for Calibrating Magnetic Instrumentsto measure the Delta Ferrite Content of Austenitic and Duplex Austenitic-FerriticStainless Steel Weld Metal, ISBN: 0-87171 -36-6 American Welding Society,Miami, Florida, 1991
ASTM A240-85, “Standard Specification for Heat-Resisting Chromium andChromium Nickel Stainless Steel Plate, Sheet and Strip for Pressure Vessels”,American Society for Testing Materials, Philadelphia, Pa
ASTM A799, “Standard Practice for Steel Castings, Stainless, InstrumentCalibration, for Estimating Ferrite Content”, ASTM International, WestConshohocken, Pennsylvania, USA, 1992
ASTM A800, “Standard Practice for Steel Casting, Austenitic Alloy, EstimatingFerrite Content Thereof”, ASTM International, West Conshohocken,Pennsylvania, USA, 1991
ASTM A890, “Standard Specification for Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-Resistant, Duplex (Austenitic/Ferritic) for GeneralApplication”, ASTM International, West Conshohocken, Pennsylvania, USA,1991
ASTM E562, “Practice for Determining Volume Fraction by Systematic ManualPoint Count”, ASTM International, West Conshohocken, Pennsylvania, USA,1997
ASTM El 301, “Standard Guide for Proficiency Testing by InterlaboratoryComparisons”, ASTM International, West Conshohocken, Pennsylvania, USA,1995
1S0 8249-85, “Welding – Determination of Ferrite Number in austenitic weldmetal deposited by covered Cr-Ni steel electrodes.”
39
.- ... . . --- —... .— —— __ ___ ___ _
7.0
. .,:.-.-.. L, .’...,. . . . .-,T?--- ,:... f,<,,<,. ~r,—.——— .-—
40
Ferrite Measurement in StainIess Steel Castings
“A Round Robin Study”
Initiated by
Dr. Carl D. LundinWilliam J. Ruprecht
Materials Joining Research GroupDepartment of MateriaIs Science and Engineering
The University of Tennessee – Knoxville
in conjunction”with
The Welding Research
and
The Steel Founders’ Society
41
Council
of America
,:v “ “ ‘+7’. ,/. .?. , .! ,. ,l-Y ,<. >,$. ..,,, .:<, ..,..>, . ,“., ,,,, -...... .’. .-.~T. ... , ., . . ,-. . . .. . ,,. ~ —
1.0 Introduction:
The UT Materials Joining Research Group is initiating a Ferrite MeasurementRound Robin study to examine the following issues:
. The reproducibility of ferrite measurement data, between laboratories, usingMagne Gage and Feritscope@ techniques
. The applicability of manufacturing cast secondary standards from static andcentrifugal castings
● A more defined correlation between ferrite measurement techniques will beestablished. These techniques include manual point counting and measurementby Magne Gage and Feritscope@.
2.0 Round Robin Timeline:
In an effort to minimize the work effort, the tirneline described in Table 1 hasbeen established. The primary goal is to send the round robin samples betweenthe Welding Research Council (WRC) committee members prior to the WRCHigh Alloys Committee meeting in May. The sample set will then proceed toSteel Founders’ Society of America (SFSA) participants before returning to UT.
Table 1: UT Ferrite Measurement Round Robin Schedule
Program Launch Date: February 24,1999Samples Arrive /D. Kotecki: March 1, 1999D. Kotecki Evacuation Period: March 1-10,1999Samples Shipped to Participant 2: March 11,1999Samples Arrive /F. Lake: March 15,1999F. Lake Evaluation Period: March 15-24,1999Samples Shipped to Participant 3: March 25,1999Samples Arrive /S. Jana March 29, 1999S. Jana Evaluation Period: March 29, 1999 through April 7,1999Samples Shipped to Participant 4: April 8, 1999Samples Arrive /T. Siewert April 12, 1999T, Siewert Evaluation Period: April 12-21, 1999Samples Shipped to Participant 5: April 22,1999Samples Arrive /J. Feldstein April 26, 1999J. Feldstein Evaluation Period: April 26,1999 through May 5,1999Samples Shipped to Participant 6: May 6,1999
-WR’CHiigh Ail!ioys I!dedmg: May 10 – ~~b ~ggg
Samples Arrive /R. Bird: May 10,1999
42
Table l(Continued~ UT Ferrite Measurement Round Robin ScheduleR. Bird Evaluation Period: May 10-19,1999Samples Shipped to Participant 7: May 20, 1999Samples Arrive /C. Richards: May 24,1999C. Richards Evaluation Period: May 24, 1999 through June 2, 1999Samples Shipped to UT: June 3, 1999Publication of Results: June 30,1999
N=. This timetable establishes 9 business days for experimental evaluation and1 business day is provided to ship the samples to the next participant.Shipping will be provided. We anticipate that the WRC members willlikely require less analysis time, as they are adequately equipped tomeasure ferrite on a routine basis. Should the Round Robin progressahead of (or behind) schedule, each participant will be appropriatelynotified.
3.0 Requests of the Participants:
The,.Materials Joining Group is grateful for your participation in this study. Wevalue your time and seek to minimize your work effort. However, the followingrequests are made to project your success.
3.1 Adherence to the Timetable:
Should a participan~ for any reason, be unable to adhere to the timetableoutlined in Table 1, please noti& the Materials Joining Research Group. UTcontacts are listed as follows:
Dr. Carl D. Lundln William J. Ruprecht IIIDirector, Materials Joining Research Graduate Research AssistantPhone: (423) 974-5310 Phone: (423) 974-5299FAX: (423) 974-0880 FAX: (423) 974-0880E-Mail: lundin@,utk.edu E-Mail: [email protected]
In the event of such an occurrence, a quick scheduling response will facilitatethe implementation of this round robin.
3.2 Questions regarding the Work Request:
If at any point in this investigation, there is a question with regard toexperimental techniques, calibration procedures, reporting of data orscheduling, feel free to contact our ofilce.
43
3.3 Su~gestions from the Partici~ants:
If you have any suggestions to improve the implementation of furtherstudies, please submit them with your data package.
Immediate suggestions which would require a modification to yourindividual test procedure should be forwarded immediately.
Comments, are always appreciated.
4.0 Work Request:
5.1 Ferrite Measurement:
Participants are asked to measure ferrite (FN) on the sample set provided.Acceptable methods of ferrite measurement include, but are not limited to,the following:
Magne Gage Feritscope@ MP3 (MP3-C)
Using the attached checklist and the provided forms, participants will beasked to calibrate (or report their current calibration) according to AWSA4.2 prior to taking measurements.
5.1 Reuortin~ of Data:
Using the attached forms, participants are asked to record their ferritemeasurements and return them to the Materials Joining Group. A mailingenvelope is included for the return of the entire package.
A Federal Express mailer has been included so that you may forward thecast standards to the next participant. Please use a Federal Express Boxand utilize suitable packing material to prevent damage during shipping.
44
5.0 Cast Sample Set:
5.1 Contents:
The sample set provided contains 12 rectanWlm blocks which have beenfabricated from austenitic and duplex stainless steels. They are labeled onthe ends with a sample code. The following table correlates the samplecode with the alloy type.
Sample Code Alloy Type
A CF8
B CF3MN
c CF8M
D ASTM A890-4A
E ASTM A890-4A
F ASTM A890-4A*
G ASTM A890-5A
H ASTM A890-5A*
I ASTM A890-5A
J CD7MCUN*
K CD7MCUN
L CD7MCUN
* Indicates that the materialwas centrifugallycast,as opposedto astaticcasting.
5.2 Condition of Samples:
Each sample has been prepared, on the measurement face, with a surfacefinish equal to a metallograpfic polish. T~s was done ~0.~~ amicrostmc~al evaluation could be performed prior to uutlatmg theround-robin. Note the presence of a scribed circle on the measurementface. No ferrite measurements are to be taken outside of this circle. Thisis done so that we may directly compare ferrite measurements withmetallographic point counting techniques.
45
6.0 Ferrite Measurement Instruction Set:
6.1
6.2
6.3
Magne Gage:
Appen&l conttis aoperator checMist mdks~ction setfor--- ‘-.-.
performing ferrite measurements with a Magne Gage.
Feritscope@:
Appendix 2 contains an operator checklist and instruction set forperforming ferrite measurements with a Feritscope@
Other:
Should a participant wish to utilize other methods of ferrite measurement,please contact the Materials Joining Group as indicated in Item 3.1 of thismanual.
7.0 Completion of Your Work Effort:
7.1 Forwarding the Sample Set to the Next Participant:
A Federal Express invoice has been provided (pre-addressed / pre-paid).Please use a standard Federal Express Box to ship the sample set to thenext participant.
7.2 Returnhw vour Data to the University of Tennessee:
A return envelope (pre-addressed) has been provided. PIease seal thismanual, containing your da~ charts, graphs and comments in theenvelope and forward it to the University of Tenuessee (c/o The MaterialsJoining Research Group).
8.0 Acknowled~ements:
We would like to acknowledge the following individuals for their guidance and supportin performing this round robin study.
Dr. Darnian Kotecki - Lincoln Electric Mr. Tom Siewert –N.I.S.T.Mr. Frank Lake - ESAB Mr. Ron Bird – Stainless FoundryMr. SUShilJana - Hobart Brothers Co. Mr. Joel Feldstein – Foster Wheeler
Mr. Christopher Richards – Fristam Pumps Inc.
46
=57 - ~F-=-T-m:. ,+. ,,,~. . ~ , ~ ..,*<,,. . .. . .. . . . .- -h.
, e.!–k , . . . . . . +.—->>.<.$: > .- — _.., ...,..
Appendix 1: Ferrite Measurement Using a Magne Gage
Please follow the checklist (below) to assure proper measurement and documentation offerrite content for each sample. You may check the boxes, located before each itemnumber, as you proceed through this study.
—
1.
2.
3.
4.
Review AWS A4.2-91, Section 4, pp. 4-6, to familiarize yourselfwith the proper methods of calibrating a Magne Gage instrument. A copyofAWSA4.2-91 has been included for your convenience and is located atthe end of this manual.
Calibrate your Magne Gage according to the specificationsoutlined in AWS A4.2-91 (Section 4).
Please include all graphs and tables used to calibrate your Magne Gageand report whether you are calibrating to Primary Thickness Standards orSecondary WeId Metal Standards. Calibration to Primary ThicknessStandards is preferred. Examples of suitable calibration curves are locatedin the AWS specification on Page 6 and are illustrated by Figure 1.
The data recording sheet is presented on Page 3 of this appendix. PIeaseprovide the Instrument Type / Serial Number, Operator Name and Date,as indicated.
Utilize the samples submitted and reference the characteristics of eachblock, as described in Item 5 of this manual. Petiorm 5 “sets” ofdeterminations as described below. Each “set” must contain 6 separatedeterminations. Only the highest FN measured will be reported for each“set” of deterrninations.
Lower the plastic “magnet guard” until it is in contact with the sample andis wholly contained within the scribed circle. Perform 6 successivedeterminations without moving the plastic “magnet guard”. This willconstitute a single “set” of determinations. Ferrite determinations takenoutside the scribed circle must be considered invalid.
Record only the highest FN, achieved from each of the 6 determinations,in the space provided. After each “set” of 6 determinations, raise theplastic “magnet guard” and lower it again, within the scribed circle>Priorto performing the next “set” of determinations. The highest determinedFN should be recorded for each individual “set” of determinations.
47
Review the data for each sample. For each sample, your data sheetshould reflective FN determinations, which are the highest FN’sobserved in each of the measurement “sets”. (Each “setJ’should becomposed of 6 individual nuwurements, obtained at-one Iocatiori with;n -the scribed circle, with the plastic “magnet guard” in contact with thesample.)
5. Upon completion of the successive ferrite determinations, return thesamples to their plastic cases and proceed to Appendix 2, FerriteMeasurement using a Feritscope@.
48
Data Sheet 1: Ferrite Measurement Using aMagne Gage
Part 1: Background Information
. . .—.— . ..- .-. .— . .Instrument Type / Serial Nurii%er:Operator Name:Date:
Part 2: Recording of Data:
Record your ferrite measurements in the following table.
Sample DeterminationI DeterminationI DeterminationIDeterminationfl.. A/. Set 1 Set 2 Set 3 Set 4LUUG
(Wghest FN) (13ghest FN) (Highest FN) !(H ighest FIN)
A
B
c
D
E I
G
H
I
J .
K
L
-, -.
DeterminationSet 5
(Highest FN)
A~pendix 2: Ferrite M~asurement Using a Feritscope@
Please foIIow the checklist (below) to assure proper measurement and documentation offerrite content for each sample. You may check the boxes, located before each itemnumber, as you proceed through this study. . .. . .~~”-”’ -----
1. Review AWS A4.2-91, Section 5, p.7, to ftiliarize yourself withthe proper methods of calibrating a Feritscope@ instrument. A copyof AWS A4.2-91 has been included for your convenience and islocated at the end of this manual.
2. Calibrate your Feritscope@ according to the specifications outlinedin AWS A4.2-91 (Section 5). Calibration to secondary caststandards will be the accepted method for this study. Standardizedforms have been provided to assist you in recording yourcalibration and are located on the following pages.
Table 1 is a sample Feritscope@ calibration form, provided courtesy ofIEYIIW-1405-98. A blank calibration form is provided, in the form ofTable 2 of this appendix. Highlight the measurements which exceedaccepted tolerances, as demonstrated (Blue Underlined) in Table 1, onyour calibration sheet (Table 2). .
If you wish to provide data for multiple Feritscopes@ and/or operators,additional copies of calibration forms maybe made from this packet.
-3. Locate the data recording sheet (Data Sheet 2) on Pages 4-5 of thisappendix. Please provide the Instrument Type / Serial Number,Operator Name and Date, as indicated. If you wish to record datafor multiple operators and/or Feritscopes@, additional copies of thedata recording sheet should be made, as needed. Pleasedifferentiate between Feritscope@ model numbers and operators inthe “background information”.
-4. Utilize the Sample Set and reference the characteristics of eachblock, as described in Item 5.0 of this manual.
By lowering the probe perpendicular to the sample, perform 10 successivemeasurements within the scribed circle. Ferrite measurements takenoutside the scribed circle must be considered invalid.
Record each measurement on the attached data sheets and report theaverage FN value observed for each sample.
50
---- -y.— .... - ,.p,+,+~.,.. . - ,,..,. .:,- %-------- — ,:, .--n----- ‘--- -
-5. Upon completion of the ferrite measurements, return the samplesto their plastic cases and review your paperwork to ensure that all data hasbeen included. This concludes ferrite measurement by the Feritscope@technique.
51
Table 1:Sample Calibration Form (Reference ILYIIW-1405-98)
Calibration Appl Appl Appl Appl Appl APPI Appl Appl Appl Appl‘Standard 4 3 1- 2 1 2 ~. .4 . *- ~
Ah 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
1stCertifiedFN 4.6 31.0 6.5 4.6 4.6 26.8 52.0 67.0 16.7 58.5
2ndCertifiedFN 16.7 52.0 31.0 10.4 10.4 37.5 58.5 73.5 26.8 73.5
3rd CertifiedFN 31.0 85.0 85.0 16.7 14.6 47.0 67.0 85.0 37.5 85.0
CertifiedFN(and I
1.7(1.4 - 2.0) 1.4 1.7
4.6 (4.3 - 4.9) 4.4 U
6.5 (6.2 - 6.8) 6.7 7.6
10.4(10.0- 10.8) 12.1 12.7
14.6(14.2- 15.0) 14.5 u
16.7(16.2- 17.2) 16.6 17.3
20.3 (19.8- 20.8) 20.3 20.5
26.8 (25.5- 28.1) 25.8 a
31.0 (29.4- 32.6) 31.3 29.8
37.5 (35.6- 39.4) 37.9 37.5
47.0 (44.6- 49.4) 46.8 49.1
52.0 (47.8- 56.2) 48.5 51.6
58.5 (53.8- 63.2) 48.6 52.2
67.0 (61.6- 72.4) 61.6 63.9
73.5 (67.6- 79.4) 67.3 69.2
85.0(78.2- 91.8) 86.9 85.3
Decision Idis-cardIdis-card
10 CheckReading
1.5 1.4
4.6 4.3
6.4 6.1
12.3 10.6
14.5 m
16.8 16.4
20.5 19.6
25.7 2S
30.6 28.0
37.8 33.2
45.7 Q J
49.0 43.0 I
47.8 42.2
m m
66.5 58.0
85.7 71.9
dis-card dis-card
on StandardIk
1.4 1.8
4.3 s
6.2 8.0
10.6 13.4
14.5 ~
16.7 18.4,
19.8 21.8
~ 27.0
28.4 32.0
33.9 37.8
$lllJ 47.2
43.6 49.1
43.7 49.1
x 64.1
58.0 70.2
71.8 89.4
usefor
0-20FN dis-card
,ngAboveCalibration
1.8 1.8 1.6 1.8
a U u s
8.1 8.0 7.5 8A
13.6 13.6 12.2 14.3
~ J&J 14.7 m
18.5 18.8 16.7 19.6
Q2.1 2z.4 20.7 23.5
27.7 27.7 26.8 w
32.2 32.7 31.3 34.5
39.4 39.9 37.7 42.5
49.1 49.4 47.5 m
53.1 53.0 50.1 58.0
55.1 52.3 48.8 56.8
67.9 68.6 63.7 68.7
74.1 73.2 70.1 72.7
98.8 86.7 90.7 87.7
use use usefor for for
30-70 15-45 60-90FN dis-card FN FN
Table 2: Participant Calibration Form
Calibration Appl Appl Appl Appl Appl Appl Appl Appl Appl ApplStandard
Air
1stCertifiedFN
2nd CertifiedFN
3rd CertifiedFN
CertifiedFN (andRange)per A4.2,
Table4 Averageof 10CheckReadingson StandardUsingAboveCalibration
~ Decision
53
.,,.-., ,,--,7 .--, .7:, ,~ , ~.
— ,.. ..- ~~,L”-,,;,,.! ‘,. m-w~p-,------ ,. :.~.-, —------ .. . . . — __
--=-,- ;--7-TJ-T7T- . -. - ..- .,-.... . .. . . ,... ,,, ,, —-. . . ,>., .! +..! - .. ,. . . ,!. . k,! ...> >.
I
24-
,,.7.- -,“-~v>>~,.y -. ~ ! , ; : ; .,-: —-T . -—n.:.. -.. —... . ..-. .
.
AWS A4.2-91
56
Keywords — instrument calibration, deltaferrite,stainless steelweld metal,
~ austeniticstainlessweld metal,L.’” duplex stainless weld metal
ANS1/AWS A4.2-91An American National Standard
Approved byAmerican National Standards Institute
February 14,1991..
Standard Procedures for
Calibrating Magnetic Instruments
to Measure the Delta Ferrite Content of
Austenitic and Duplex Austenitic-Ferritic
Stainless Steel Weld Metal
Supersedes ANSI/AWS A4.2-86
Prepared byAWS Committee on Ftier Metal
and The Welding-ResearchCouncil Subcommitteeon WeIdingStainless SteeIs
Under the Direction ofAWS Technical Activities Committee
Abstract
.. .
L
Calibrationproceduresare specifiedfor a numberof commercialinstrumentsthat can then providereproduciblemeasurementsoftheferritecontentofausteniticstainlesssteelweldmetaIs.Certainoftheseinstrum~ntscanbefurthercalibratedfor measurementsof the ferritecontentofduplexaustenitic-fernticstainlesssteelweldmetals.Calibrationwithprimarystandarcis(non-magneticcoatingthicknessstandardsfromtheU.S.NationalInstituteofStandardsandTechnology)k the preferredmethodfor appropriateinstruments.Alternatively,theseand other instrumentscanbecalibratedwithweldmetalsecondarystandards.
Reproducibilityofmeasurementaftercalibrationisspecitled.Problemsassociatedwithaccuratedeterminationofferriteare described.
om American Welding Society1550 N.W. LeJeune Road, P.O.BOX351040,Miarnij Florida 33135
.. .
Statement on Use of AWS Standards
?$- ,
Ml standmis (codes,specitlcations,recommendedpractices,methods,cl=ificatims, and guides)of the American uWeldingSocietyare voluntaryconsensusstandardsthat havebeen developedin accordancewith the rules of theAmericanNationalStanda~dsInstitute.WhenAWSstandardsaree$her.incorporatedin,ormadepart of,documenq _that are includedin federalor state lawsand regulations,or the regulationsof other governmentalbodies,theirprovisionscarrythe fulllegalauthorityof the statute. In suchc=es, my changesin thoseAWSstandardsmustbeapprovedby the governmentalbodyhavingstatutoryjurisdictionbeforetheycanbecomeapart of thoselawsandregulations.In WC=CS,thesestandardscarrythefulllegalauthorityofthecontractorotherdocumentthat invokestheAWSstandards.where this contractualrelationshipexists,changesin or deviationsfromrequirementsof an AWSstandardmustbe by agreementbetweenthe contractingparties.
International Standard Book Numben 0-87171-361-6
American WeldingSociety, 550 N.W.LeJeune Road, P.O. Box 351040,Miami, Florida 33135
@1991by Anerican WeldingSociety. AUrights reservedPrinted in the United States of America
Note: The prim=y purpose of AWS is to serveand benefit its members. To this end, AWS provides a forum for theexchange, consideration, and discussion of ideas and proposals that are relevant to the welding industry and theconsensusof whichforms the basisfor thesestandards. Byproviding such afoq AWSdoes not assumeany dutiestowhicha user of thesestand~ds maybe required to adhere. Bypublishing this standard, the knerican WeldingSocietydoes not insureanyoneusingthe informationit containsagainstanyIiabiIityarisingfromthat me. PubIiCationof astandardby the AmericanWeldingSocietydoesnot carrywithit anyrightto make,use,or sellanypatenteditems.Usersoftheinformationinthisstandardshouldmakeanindependentinvestigationofthevalidityofthat informationfor theirparticularuseand the patent statusof anyitemreferredto herein.
With regard to technical inquiries made concerning AWS standards, oral opinions on AWS standards may berendered. However,such opinions representonlythe personal opinions of the particular individualsgivingthem. Theseindividuals do not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions orinterpretations of AWS.In addition,oral opinionsare informalandshouldnot beusedasa substitutefor an offici~interpretation.
This standard issubjectto revisionat anytime by the AWSFiier Metal Committee.It must be reviewedeveryfiveyearsand if not revised,it must be either reapproved or withdrawn. Comments (recommendations, additions, or deletions)and any pertinent data that may be of use in improving this standard are requested and should be addressed to AWSHeadquarters. Such comments will receivecareful consideration by the AWSFtier MetalCommitteeand theauthorof the commentswillbe informedof the Committee’sresponseto the comments.Guestsat-einvitedto attend allmeetingsoftheAWSFfler MetalCommitteetoexpresstheircommentsverbally.Proceduresfor appealofanadversedecisionconcerningallsuchcommentsareprovidedintheRulesofoperation oftheTechnicalActivitiesCommittee.AcopyoftheseRulescanbeobtainedfromthekunericanWeldingSociety,550N.W.Le.JeuneRoad,p.o. Box351040,Miami,Florida33135.
c)F
e,.
.,-.....
L.’
Personnel
AWS Committee on FiIler Metal
D. J. Kotecki, ChainmanR. A. LaFave, Ist Vice Cha&nmn
J. P. Hunt, 2nd Vice Chairman
H. F. Reid, Secretary
D. R. Amos
B. E Anderson
K. EBanks
R S. BrOW71
J. Caprarola, Jr.
L J. Chr&ensen*R J Christofe[
D.A. DeISignore
H. U? Ebert
S. E FerreeD.A. Fih.k
G. Hal.lrtrom, Jr.
R L HarridR W. Heid
D. C. .HeIton
W. S. Howes
RU?JdR B. Kbdiyala
P. A. Kamme@
J E Kelly
G. A. Ki.m3kyN. E Lurson
A. S. Luurenson
G. H. MacShane
D. 1? ManningM. T. MerIo
S. J. Mem.ck
G. E Metzger
J. W. Mortimer
C. L hhd
K Ogata*
J. PayneR L Petz.dee
E W Pickeri@ Jr.M, A. Quintana
S. D. Reynolc&, Jr.*
L E Roberts
D. Rozet
*Advkor
..!
The Lincoln ElectricCompanyElliott CompanyINCO Alloys InternationalAmerican WeldingSocietyWestinghouseTurbine PlantAlcotecTeledyneMcKayCarpenter TechnologyCorporationAlloy Rods CorporationconsultantconsultantWestinghouseE1ectricCompanyExxon Researcliand Engineering CompanyAlloy Rods CorporationThe Lincoln ElectricCompanyUSNRC-RIIR. L. Harris AsociatesNewport News ShipbuildingconsultantNational ElectricalManufacturers AssociationChrysler MotorsTechalloyMaryland, IncorporatedEuteetic CorporationEutectic CorporationMaryland SpecialtyWue “Union Carbide, Industrial Gas DivisionconsultantMAC AssociatesHobart Brothers CompanyTri-Mar~ IncorporatedTeledyneMcKayConsukantconsultantNaval Se*Systems CommandKobe Stee&LimitedSchneider Servi& InternationalWall Colmonoy CorporationconsultantGeneralDynamics CorporationWestinghouseEIeetricPGBUCanadian WeldingBureauconsultant
Ui
—
.-
P. K. Salvesen
H. S. Sayre”
O. W. Seth
R W. Straiton*.- R D. Sutton-
R A. Swati
J. W. Tackett
RD. Zhomas, Jr.
R limerman”
R T Webster
A. E Wiehe*
X A. Wiehe
W L Wilcox
E J. Wiiofi
K G. Weld
Z J. Wonder
American Bureau of ShippingconsultantChicago Bridge and Iron CompanyBechtel Group, IncorporatedL-TeeWeldingand Cutting .Systems ~ ---WeldersSupplyHaynes International IncorporatedR. D. Thomas and CompanyCONARCO, S. A.TeledyneWah ChangconsultantArcos AlloysconsultantconsultantAqua Chem IncorporatedVSE Corporation
AWS Subcommittee on Stainless Steel Fdler Metals
D. A. DelSignore, Chairman
H. E Reid, Secretary
E S. BabirhKEBanks
R S. Brown
R A. BusheyR J. Chr&toffel
D. D. CrockettEA. Flynn
A. L Gombach*B. Herbert*
J. P. HuntR B. ~adiyala
P. A. KarnmeF
G. A. Ki.mkkyw E. ZUyo*
G. H. MacShane
A. H. klille~X Ogata*
M. Pi P>ekh.
E. K Pickering, Jr.
L J. Privoznik-C.E. Rid2nour
H. S. Sayre*R W Straiton
R A. SwainJ. G. Tack
R 2%nerrnan*
W. A. W~he*
W. L Wiiox
D. W. Yonker, Jr.
●Advisor
WestinghouseElectric Corporation&nerican WeldingSociety%ndw IncorporatedTeledyneMcKayCarpenter TechnologyCorporationAlloy Rods CorporationconsultantThe Lincoln Electric CompanySun R&MChampion WeldingProductsUnited T=hnologies-ElliottInto Alloys InternationalTechalloyMaryland, IncorporatedEutectic CorporationMaryland Specialty W~eSandvik Steel CompanyMAC AssociatesDISCKobe Steel, Ltited
c)
.;...\
i,. i
.. ..__
Hobart Brothers CompanyconsultantconsultantTri-MarlGIncorporatedconsultantBechtelGroup, IncorporatedWeldersSupplyArmco, IncorporatedCONARCO, s. A.Arcos AlloysconsultantNational Standards Company
-,
f- ‘.,
b’
WRCSubcommitteeon WeldingStainlessSteel
D. J. Kotecki, Chairman Lincoln Electric CompanyD.A. DelS&nore, Secretary WestinghouseElectricCorporation
D. K Aidun ClarkSon CollegeH. C. Campbell . Consultant .— . -:.:--.
G. M. C&ini
S. A. David
J G. Fek&tein
A. R Herdt
J. E. Indacochea
W. R Keaney
E B. LakeG. E. Linnert
J. Lippold
EA. LJriaC. D. Lundh
D. B. O’Donnell
E. W. Pickering
D. W. Rahoi
. J. Salkin
J. L Scott
E. A. SchoeferZ A. Siewert
C. Spaeder
R Swain
R D. 2%omm, Jr.M. J. Iinkler
D. M. VandergriY
R M. Walkosak
AlleghenyLudlumSteelOakRidgeNationalLaboratoriesTeledyneMcKayU. S. NuclearRegulatoryCommissionUniversityof Illinoisat ChicagoGeneralAssociates~Oy RodsGMLPublicationsEdisonWeldingInstituteNiobiumProductsCompanyUniversityof Temessee11’JCOAlloysInternationalconsultantCCM2000PrecisionComponentsCorporationWeldMoldconsultantNationalInstituteof Standardsand TechnologyLehighUniversityWeldersSupplyR. D. Thomasand CompanyOntarioHydroJ. A.JonesAppliedResearchWestinghouseE1ectricCorporation
v
-r—- --, ,., ,,. . ,.J. ,,. . ..”.%.. .. . . v.,,..,...!.1-- . .. ,, -. . . . ...~r-<- ,, ,,. ; , ,,, -..: >%”~,,., ~.—-—-------- — —._
Foreword—..--
(This Foreword isnot apart of ANSI/AWS A4.2-91,StandardProcedures for CalibratingMagnetic Instruments to
Measure the Delta Ferrite Content of Austenitic and Duplex Amtenitic-Ferritic Stainless Stee[ Weld Metal, butis
included for information p~oses only.)
This document k a revisionof the Standard Procedures for Calibrating Magnetic Instruments to Measure the Deha
Ferrite Content of Amtenitic StainlessSteel Weld Metal, fmt published in 1974and revisedin 1986.~ revisionwasby the Subcommittee on Welding Stainless Steel of the Welding Research Council and by the AWS Ffler MetalCommittee. The current revision expands the range of calibration and measurement to include, for the f~t time,duplex austenitic-ferrhicstainless steelweld metals.
A certain minimum ferrite content in most austenitic stainlesssteel weld metals is useful in assuring freedom frommicrof~sures and hot cracks. Upper limits on ferrite content in austenitic stainlesssteelweldmetals can be imposed tolimit corrosion in certain media or to limit embrittlement due to transformation of ferrite to sigma phase during heattreatment or elevatedtemperature service.Upper Iimits on ferrite content in duplex austenitic-ferriticstainless steelweld metals can be imposed to help assure ductility, toughness, and corrosion resistancein the as-weldedcondition.
Reproducible quantitative ferrite measurements in stainlesssteelweldmetals are therefore of interest to ftier metalproducers, fabricators of weldments, weldment end users, regulatory authorities, ~d insurance companies.
Comments and suggestionsfor improvement are welcome.Theyshould besent in writing to Secretary, Filler MetalCommittee, AmericanWelding Society,55o N.W. Le.JeuneRoad, P.O. BOX 351040,Miamij FL 33135.
v..
Table of Contents ~ ----- —.. ”.. -.-_z- ., ---a-
Page No.
Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....ul
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
fit of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....
w
L&t of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....
Vu.I
1.
2.
3.
4.
s.
6.
7.
8.
9.
b
J,A
,
d
,
fcope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Definitions . . . . . . . . . . . . . . . . ., . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1?.1 Delta Ferrite . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Draw Ffig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12,3 FerriteNumber(F’N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 Primary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5 WeldMetalSecondaryStandar& . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Calibration Methods –. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.1 Primary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.2 Secondmy Stadards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Calibration of Magne-Gage-Type Imtruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1 Calibration by Means of Primary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.2 Calibration by Mea.nsof Weld Metal Secondary Standuds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Calibration of Ferkrcopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1 Crdibration by Means of Primary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.2 Calibration by Means of Weld MetaISecondary Stmduds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Calibration of Ihspector Gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1 Calibration by Means of Primary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.2 Calibration by Means of Weld Metal Secondary Stad=ds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Calibration of Other Imrruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1 Calibration by Means of Primary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.2 Calibration by Means of Weld Metal Secondary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Use of CalibratedInstruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1 MaintainingCalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.2 Variations in Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.
Signj?cant Figures in—Repomhg Measurement kds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.,-.
9.1 Calibration Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lU
9.2 Measurement Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Appendix . .- Al.
A2.A3.A4.A5.A6.A7.
-,~.1:1.
Acknowledgment . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Ways of Expressing Ferrite Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Cautions on the Use of Ferrite Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Standards for Instrument calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Effect of Ferrite Size, Shape and Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Use of Calibrated Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
vii
f-j
..-
...1.
-. ------ .. . . .--—
List of Tables - “- - ~-./
Table Page No.
1
2
3
4
5
6
7
8
91011
Ferrite Numbers(FN)for PrimaryStandards Calibrationof k~rnmt-s Usinga MagneGageNo. 3 Magnetor Equivalent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2FerriteNumbers(FN)for PrimaryStandardsfor Feriucope(Fwrkescope.)ModelFE8-K~Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Ferrite Numbers (FN) for Primary Standards for Inspector Gage Calibration . . . . . . . . . . . . . . . . . . . . . . 4Maximum AllowableDeviation, Calibration Point to Calibration Curve, for Instruments Being -Calibrated with Weld Metal Secondary Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Tolerance on the Position of Calibration Points Using Primq Standards . . . . . . . . . . . . . . . . . . . . . . . . . 5Maximum AllowableDeviation of the Periodic Ferrite Number (FN) Check for Feritscopes . . . . . . . . . . 7Maximum AllowableDeviation of the,Periodic Ferrite Number (FN) Check for Inspector Gages. . . . . . 8Maximum AllowableDeviation of the Periodic Ferrite Number (EN) Check for Magn@age-TypeInstruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Expected Range of Variation in Measurements with Calibrated Magne-Gage-TypeInstruments . . . . ...10Expected Range of Variation in Measurements with Calibrated Feritscopes . . . . . . . . . . . . . . . . . . . . . ...10Expected Range of Variation in Measurements with Calibrated Inspector Gages . . . . . . . . . . . . . . . . . . . . 10
List of Figures
Figure Page No.
1 Examples of Calibration Curves for Two Magne-GageInstruments, Each with a No. 3 Magnetfor Measuring the Delta Ferrite Content of Weld Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Al Magne-Gage-TypeInstruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
A2. Ferntescope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
A3 Inspector Gage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A4 Ferrite Indicator (Severe Gage) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A5 Foerster Ferrite Content Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
—
...Vul
--- ., ~——,.., J ,,,. bf, .,.—;?,—=--: . ..—,,.< ,. .
.F%,;
-.”
f-.,,
‘u
L%.:
Standard Procedures for Calibrating
Magnetic Instruments to Measure the
Delta Ferrite Content of Austenitic zmd-Duplex -.- .-=—.——----
Austenitic-Ferritic Stainless Steel Weld Metal
1. Scope molten state upon freezing.Much of the original ferrite
1.1 This standard prescribesprocedures for the calibra-that formed upon freezingtransforms to austenite dur-
tion and maintenance of calibration of instruments foring cooling.
measuring, by magnetic attraction or permeability, thedelta ferritecontent ofan austenitic or duplex austenitic- 2.2 Draw Filing. A weldpad surface preparation tech-ferritic stainless steel weld metal in terms of its Ferrite “ nique suitable for subsequent ferritemeasurements onlYNumber (EN). _ up to about 20 FN. (See8.2.)A sharp clean 14-inchmill
1.2 A thorough review of the Appendix is recom-mendedbefore anyinstrument is calibrated or used.TheAppendix presens background information which isessential to understanding the many problems and pit-falls in detedng and specifyingthe ferrite content ofweld metals.
1.3 Calibration can be accomplished with&e use of theNational Institute ofStandards and Technology(NET,formerly National Bureau of Standards) primary stan-dards or weldmetal seconds’y standards. At the presenttime, ody three instruments ~agne-Gage (iicluding atorsion balanceusingessentiallya Magne-GageNumber3 magnet, hereinafter referred to as a Magne-Gage typeinstrument), Feritscope(also sometimesidentied asFerritescope), and Inspector Gage]can be calibrated bythe use of NIST primary standards, and the range ofpossiblecalibration depends upon the particular instru-ment (seeTables 1,2, and 3).This is not an endorsementof any partiwlar instmment. (See 3.1.)
— —
2. Definitions’
2.1 Delta Ferrite. The ferrite which remains at roomtemperature from that which was formed from the
1. ForAWStermsanddefinitions,referto thekitesteditionofAIISI/AWSA3.0,St&d Terms and @initions. Heasenote thatsomeofthetermsanddefinitionsusedin thispubli-cation are not includedin AWSA3.O.They are eithernewtermsdefinedafterthelatestrevisionofA3.Oor theyareusedspecMcto thispublication.
bastard file which has not been contaminated by ferro-magnetic materials, held paraUelto the base metal andperpendicular to the long axis of the weld metal sample,is stroked smoothly with a fm downward pressure,forward and backward along the weld length. No crossftig is done. The ftihed surface is flat with at leasta 1/8-in. (3.2 mm) width where all weld ripples areremoved.
23 Ferrite Number (FN). An arbitrary, standardizedvalue designating the ferrite content of austen.iticandduplex austenitic-ferritic stainkss steel weld metal (seeAppendix X?).
2.4 Primary Standards. Specimenswith accuratethick-nessof non-magnetic material on carbon steelbaseplatecontaining0.25percentcarbon maximum. Each primarystandard is assigned an FN of an equivalent magneticweld metal, this assigned value being spetilc to a par-ticular make (and model, if applicable) of measuringinstrument (i.e., Magne-Gage, Feritscope, or InspectorGage). (See Appendix M. I.)
The primary standards upon which the standardprocedures are based are the NISTS sets of coatingthickness standards, consisting of a very uniform layerof electroplated copper covered with a chromium flashover a carbon steel base. (See Appendix A4.L)
2.5 Weld Metal Secondary Standards. Small weldmetal pads certifiedfor FN in a rn~er traceabletothesestandardprocedures.(SeeAppendixA4.2.)
1
2
Table 1Fem”te Numbers (FN) for Primary Standards
Calibration of lnstrwnenis Using a Magne-Gage No. 3 Magnet or Equivalent
(Magne-Gage-Type Instruments)
roils mm. . FN
1.20 0.03051,25 0.03181.30 0.03301.35 0.03431.40 0.03561.45 0.03681.50 L03811.55 0.03941.60 0.04061.65 0.04191.70 0.04321.75 0.04451.80 0.04571.85 0.04701.90 0.04831.95 0.04952.00– 0.05082.05 0.05212.10 0.05332.15 0.05462.20 0.05592.25 0.05722.30 0.05842.35 0.05972.40 0.06102.45 0.06222.50 0.06352.55 0.06482.60 0.06602.65_ 0.06732.70 0.06862.75 0.06992.80 0.07112.85 0.07242.90. 0.07372.95 0.07493.00 0.07623.1 0.07873.2 0.0813
-3.3 0.08383.4 0.0864
89.587.585.783.982.380.679.177.676.274.973.672471.270.068.967.866.865.864.863.963.062.261.360.559.758.958.257.556.856.155.454.854.153.552.952.351.850.749.648.647,7
—
roils mm FN .
3.53.63.73.83.94.04.14.24.34.44.54.64.74.84.95.05.25.45.65.86.06.26.46.66.87.07.58.08.59.09.5
10.010.511.011.512.012.513.013.514.014.5
0.08890.0914o.09@0.09650.09910.10160.10410.10670.10920.11180.11430.11680.11940.12190.12450.1270.1320.1370.1420.1470,1520.1570.1630.1680.1730.1780.1910.2030.2160.2290.2410.2540.2670.2790.2920.3050.3180.3300.3430.3560.368
46.845.945.144.343.542.742.041.340.740.039.438.838.237.737.136.635.634.733.832.932.131.430.730.029.328.727.326.024.823.722721.821.020.219.518.818.217.617.116.616.1
lik. , . mm .. FN
5.05.56.06.57.07.58.08.5,9.0,9.5!0.0!0.511.(J11.5~o22523.023.524.024.525.025.526.026.527.027.52a.o28.529.029.530.031.032033.034.035.0
0.3810.3940.4060.4190.4320.4450.4570.4700.4830.4950.5080.5210.5330.5460.5590.5720.5840.597
. 0.6100.6220.6350.6480.6600.6730.6860.6990.7110.7240.7370.7490.7620.7870.8130.8380.8640.889
36.0 0.91437.0 0.94038.0 0.96539.0 0.99140.0 1.016
15.615.214.814.414.013.713.313.012712.412.111.811.611.311.110.810.610.410.210.09.89.69.49.29.18.98.78.68.48.38.17.97.67.47.16.96.76.56.36.26.0
lik mm . FN
Lo2.03.0$.05.06.07.08.09.00.01.02.03.04.0i5.oi6.Oi7.Oi8.O;9.0m.o51.052053.054.0S5.O66.067.068.069.070.071.072073.074.075.076.077.078.079.080.0
1.0411.0671.0921.1181.1431.1681.1941.2191.2451.2701.295.1.32113461.3721397L4221.4481.4731.4991.5241.5491.5751.6001.6261.6511.6761.7021.7271.7531.7781.8031.8291.8541.8801.9051.9301.9561.9812.0072032
5.85.75.55.45.25.15.04.84.74.64.54.44.34.24.14.03.93.83.753.673.593.523.443.373.303.243.173.113.052.992932.882822n2722.672622572.532.48
3. Calibration Methods
3.1 Primary Standards. Since each type of ferritemeasuring instrument responds differently to the pri-mary standards, it is not possible to specify a genericcalibration procedurq rather, it is necessaryto tailor acalibration procedure to a particular instrument. As ofthe previous revision of this standard, three types ofinstruments had been subjected to extensivetesting, and
detailed procedures and appropriate tables and valueswere contained in that standard to provide for theircalibration to primary standards. These instrumentsare the Ma~e-Gage-type instruments, Feritscope, andInspector Gage. At the time of publication of ANSI/AWSA4.2-86,however,the probe of the Feritscope waschmged so that the Feritscope calibration table doesnotapply to newer instruments. This situation continues.Since that time, the range of calibration by prim~
Table 2r% Ferrite Numbers (FN) for Primary Standards for Feritscope (Ferritescope)
,,.,i -Model FE8-KF Calibration (See 5.1.
-“Thickness
roils mm FIN
7.07.58.08.59!09.5
10.010.511,011.512,012.513.013.514.014.515.015.516.016.517.017.518.018.519.019.520.020.521.021.5220
0.1780.1910.2030.2160.2290.2410.2540.2670.2790.2920.3050.3180.3300.3430.3560.3680.3810.3940.4060.4190.4320.4450.4570.4700.4830.4950.5080.5210.5330;5460.559
25.824.323.021.820.719.718.818.017.216.615.915.414.814.413.913.513.112712.312.011.711.411.110.810.610.310.19.99.79.59.3
G.,
Tlickness
roils mm m
22.523.023.524.024.525.025.526.026.527.02’7.528.028.529.029.530.031.032.033.034.035.036.037.038.039.040.041.042.043.044.045.0
(3.572 = 9.10.584 8.90.597 8.70.610 8.60.622 8.40.635 8.30.648 8.10.6643 8.00.673 7.80.686 7.70.699 7.60.711 7.40.724 7.30.737 7.20.749 7.10.762 6.90.787 6.70.813 6.50.838 6.30.864 6.10.889 6.00.914 5.80.940 5.60.965 5.40.991 5.31.016 5.151.041 5.01.067 4.91.092 4.751.118 . 4.61.143 4.5
standzqds of Magne-Gage-type instruments has beenexpanded to include FNs appropriate to duplex austen-itic-ferntic stainkis steel weld metals.
3.2 Secondary Standards
3.2.1 Calibration by means of primary standards isthe preferred method of maintaining calibration ofappropriate instruments. But the need for frequent in-process checks is recognized along with the fact thatprimary standards are not necessarily“durable” for fre-quent use outside of a laboratory enviro~ent. There-fore, it is recommendedthat a set of secondarystandzdsbe used for frequent in-process checks. (See AppendixA4.2.)
3.2.2 When secondary standards are used, the aver-age reading on each standard shall be within the maxi-
Thickness
“ 46.047.048.049.050.051.052053.054.055.056.057.058.059.060.0
.61.062.063.064.065.066.067.068.069.070.072.074.076.078.080.0
1:1681.1941.2191.2451.2701.2951.3211.3461.3721.3971.4221.4481.4731.4991.5241.5491.5751.6Q01.6261.6511.6761.7021.7271.7531.7781.8291.8801.9301.9812032
— 4.4 -4.34.24.14.03.93.83.73.63.53.43.33.2
3.153.1
2.9829
283275
272.6
2.552.5
. 2.422352232.15201.91.8
mum allowable deviation from the calibration curveasspecifiedin Table 4. If a maximum zdlowabledeviationis exceeded, the instrument cannot be considered calib-rated. Calibration with primary standards or instru-ment repair is then necessary.
3.23 Instruments for which-here is not a detailedcalibration procedure in this standard utilizing primvstandards can only be calibrated using secondary stan-dards. Refer to Section 7 for proper calibration instruc-tions.
33 For all calibration methods and instruments, therange of calibration is defined by the intend of FNsbetween and including the lowest FN standard and thehighest FN stand=d used in developing the calibrationaccording to the corresponding procedure.
4
Table 3
>30_29.929.028.127.326.525.825.124.423.823.222.622.021.521.020.520.019.619.218.718.418.017.617.2
.
Thickness
roils mm FN
22.5 0.572 16.9 ~23.0 0.584” 16.6Z+.5 0.597 16.224.0 0.610 15.924.5 0.622 15.625.0 0.635 15.425.5 0.648 15.126.0 0.660 14.826.5 0.673 14.527.0 . 0.686 14.327.5 0.699 14.128.0 0.711 13.828.5 0.724 13.629.0 0.737 13.429.5 0.749 13.130.0 0.762 12.931.0 0.787 12532.0 0.813 12.233.0 0.838 11.834.0 0.864 11.435.0 0.889 11.136.0 0.914 10.837.0 0.940 10.538.0 0.965 10.239.0 0.991 9.940.0 1.016 9.741.0 1.041 9.4420 1.067 9.243.0 1.092 9.044.0 1.118 8.745.0 1.143 8.5
Ferrite Numbers (FN) for Primarv Standards for Inspector Gage Calibration*
===1
~r:’.::
Thickness .,\ . .
7.0 0.1787.5 0.1918.0 0.2038.5 0.2169.0 0.2299,5 0.241
10.0 0.25410.5 0.267ILO 0.27911.5 0.29212.0 0.30512.5 0.31813.0 0.33013.5 0.34314.0 0.35614.5 0.36815.0 0.38115.5 0.39416.0 0.40616.5 0.41917.0 0.43217.5 0.44518.0 0.45718.5 0.47019.0 0.48319.5 0.49520.0 0.50820.5 0.52121.0 0.53321.5 0.54622.0 0.559
“ThistableshallbeUSCdonly forcalibratingInspcetorGageModelNumber11I with6F or 7F sde for measuringthe deltaferritecontentofas-welded austetitic.misd=ssteel weld metals.
Table 4Maximum Allowable Deviation,
Calibration Point to Calibration Cuwe,for Instruments Being Calibrated with
Weld Metal Secondary Standards
FerriteNumberRange M~um AllowableDeviation
oto5FN * 0.30over5 to 10FN * 0.30over10to 15FN * 0.40over15to 25FN * 0.50over25 to 50FN * 594of assignedFNover50to 90FN *8% of assignedFN
nils mm m
46.0 -1.168 8.3 -- .47.0 1.194 8.148.0 1.219 7.949.0 1.245 7.750.0 1.270 7.551.0 1.295 7.452.0 1.321 7.253.0 1.346 7.054.0 1.372 6.955.0 1.397 6.756,0 1.422 6.657.0 1.448 . 6.458.0 1.473 6.359.0 1.499 6.160.0 1.524 6.061.0 1.549 5.962,0 1.575 5.7563.0 1.600 5.664.0 1.626 5.565.0 1.651 5.466.0 1.676 5.367.0 1.702 5.168.0 1.727 5.069.0 1.753 4.970.0 1.778 4.872.0 1.829 4.6 9< ‘74.0 1.880 4.476.0 1.930 4.278.0 1.981 4.080.0 2032 3.85
4. Calibration of Magne-Gage-Type2 -Instruments
4.1 Calibration by Means of Primary Standards. AllMagne-Gage-typeinstruments can be calibrated by thefollowing procedure. Torsion balances other than aMagne-Gagemay not require use of counterwei@Wsothat statements regarding ranges of calibration may notapply. However, the requirements for the number ofstandards for ctilbration over a specificI?Nrange shall
di2. Trademarkof Magne-GageSales& Service.(SeeAppen- ‘.dixA6.1.)
applyto allMagne-Gage-typeinstruments.(SeeAppen-dix A6.1.)
%.,.‘*i 4.1.1 The FNs shallbe assignedfromTable 1to each
.“ of the available primary standards (coating thicknessstandards) as defined in 2.3. For thicknesses betweenthose given in the table, the FNs shall be interpolated ascloselyas possible. Alternatively,FN may be calculateddirectlyfrom oneof the twofolloting formulas
For thickness (T) in mi.kln(~ = 4.5891-0.50495 in(T) -0.08918 [ln(T)]2
+ 0.01917@(T)]3 -0.00371 @(T)]4
For thickness(T) in mmh@$) = 1.8059-1.11886 in(T) -0.17740 [hI(T)]2
-0.03502 @(T)]3 -0.00367 ~n(T’)]4
See Section 9 for informationon the precMonof themeasurements.
4.1.2 Magne-Gage-type instruments are sensitive topremature magnet detachment from a standard or froma sample due to verysmallvibrations. The Magne-Gageminimizes, but does not eliminate, this effect, as com-pared to other torsion balances. Repetitive measure-.ments at a givenpoint willyielda range ofFN valuesdueto this effect, and the range increases with increasing~. With a Magne-Gage, above 20 FN, it is necessaryto make several measurements at any given point of a
P-, standard or sample, and to accept only the highest FN“, as the correct value for that point. With other Magne-
4’ Gage-typeinstruments (torsion balances)this practice isnecessaryfor all levelsof I?N.
4.1.3 A Magne-Gagecan be usedfor measurementsovera range of about30 FN with a singlecalibration.The exact rangeto be used at any giventime is deter-minedbythechoiceofacounterweight(ifany)addedtothe balancebe- of the instrumentat a holeprovidedfor this purpose.The hole is located about 1.5inches(38mm)from the fulcrumoppositefrom the point ofsuspensionof themagnet(seeFigureAl). Careshouldbe takenthat thecounterweight,ifused, isfreeto swingwithouttouchinganyotherpart oftheinstrumentwhenthe magnet is in contact with specimenor standards.Without a countemeigh~ a Magne-Gagewill coverfromOto about 30FN. Whh a counterweightof about7.5grams,a Magne-Gagewillcoverfrom about 30 to60 ~, with a countenveightof about 15g, the mea-surementrangeti beabout 60to 90I?PT.Exactrangeswill depend upon the preciseweightof the counter-weightand upon the strength of the magnetin use. Aseparatecalibrationisrequiredfor eachcounterweight,and recalibrationis required wheneverthe magnet ischanged.
-%,.
(J 4.1.4 Without a countenveight, eight or more pri-.; mary standards shall be used, with nornid thicknesses
that provide corresponding Ferrite Numbers well dis-
tributed over the range of Oto 28 FN. Wkh the No. 3magnet in place, the zeropoint (the white dial reading atwhich the magnet lifts free from a completely nonmag-netic material) shallbe determined.If a counterweight isused, five or more primary standards, similarly welldistributed, shall be used, but no zero point can bedetermined. In either case, the white dial reading foreach oftheavailableprimarystandards coveringthRFN .range of interest shall then be determined. (See Appen-dix A4.1).
4.1.5 The whitedial readingsshall be plotted on Car-tesian coordinate paper versus the FNs as illustrated inFigure 1. If no counterweight is used, the zero pointreading (whitedial readingwhen the magnetjust barelyliftsfrom a nonmagneticmaterial)onthedial of the gagecan be included as OFN.
4.1.6 A“best fit’’straight lineshall be drawn throughthe points plotted in accordance with 4.1.5. Altern-atively,a linear regressionequation shall be fit to the datacollected as described in 4.1.4. Magne-Gages tested todate have produced a straight lineup to at least 10FN.Most yield a straight line through all points, but somehave shown a slight bend. & example ofeachisshownin Figure 1. For acceptablecalibration, all points mustfall within the maximum allowable deviations shown inTable 5. If any of the calibration points fall outside oftheallowed variations, the data shall be restudied, or themanufacturer of the instrument shall be consulted, orboth.
4.1.7 Two common sources of discrepant readingsduring calibration (as well as during measurement) aremechanicrdvibrations and dirt (usually magnetic par-ticles) clinging to the magnet. Either factor tends toproduce premature detachment of the magnet from thesample, with a correspondingly low FN determination(high white dial reading). A vibration-free environmentis essentiaI to accurate FN deterrninatiou especiallyabove 15 FN. Wiping of the magnet end with a clean,
Table 5Tolerance on the Position of
Calibration Points Using Primary Standards
Ferrite N=ber Range —MaximumAllowableDeviation
oto5 * 0.40over5 to 10 * 0.50over10to 15 * 0.70over15to 20 * 0.90over20 to 30 * 1.00over 30 to 90 *5% of assignedm
NOW The maximumvariations in the positionof the cdibmfionpointsfromtbe cutwe(exampleis shownin ?3g.1)occurwhentheprim~ thickrKssstandardsare at the maximumfivepercentv&a-tionfromthecenifiedthicknesses.
140
130
120
110
100
--d .-.-
=%
90
80
70
60
50
40
30
20
10
0’ 4“ i“ 12 16 20 24
FERRITE NUMBER
NOTE A different set of coating thickness standards was used for each instrument, although the sets included thesame standard numbers
DATA FOR THE CURVES
NBS COATING GAGE #1 CALIBRATION GAGE #2 CALIBRATIONTHICKNESSSTANDARD roils mm FN WHITE DIAL mi16 mm FN WHITE DIAL
1312 8.2 .208 25.5 13.21313 10.2 .259 21.5 28.0 9.8 .249 22.2 27.01314 14.7 .373 15.9 53.0 15.0 .381 15.6 57.01315 19.2 .488 12.6 68.0 19.7 .500 12.3 74.01316 24.5 .622 10.0 76.0 24.3 .617 10.1 84.11317 31.2 .792 7.8 84.0 30.5 .775 8.0 93.51318 43.0 1.092 5.5 92.0 45.5 1.156 5.2 107.31319 63.0 1.600 3.4 99.0 60.5
Zero Point
1.537 3.6 114.80.0 111.5 0.0 132.0
Figure 1 —Examples of ~alibration Curves for TWOMagne-Gage Instruments,Each with a No. 3 Magnet for Measuring the Delta Ferrite Content of WeId MetaIs
lint-freecloth is suggestedwhen dirt is encountered. Incase of doubt, examination of the magnet end under amicroscope is appropriate. ..
4.1.8 The graph plotted as in 4.1.6, or a regressionequation fit to it, may now be used to determine the FNsofstainlesssteelweldmetalsfrom the whitedial readingsof the instrument obtained on those weldmetalswith thesame No. 3 magnet and countemeight (ii used).
4.2 Calibration by Means of Weld Metal SecondaryStandards
4.2.1 Calibration by primary standards is the recom-mended method, as previously mentioned, but caliim-tion umg secondarystandards is acceptable: l%e OT
3. Weldmetalsceondarystandardshavebeencommerciallysold by The VJeldmgInstitute, AbingtonHall, Abington,Cambridge,CBI5AL UnitedKingdom.
3.Y,.:
. .
.\‘)
Q..!: .
J1$..
more such standards are required for calibration curves 5.1.2 The manufacturer’sinstructions with regard tofor Oto 15m, eightor more are requiredfor calibration the use of the instrument and the adjustments of the
% curves for 0 to 30 ~, ~d fiveor more are required for.— scale shall be followed...,P
J.any range of30F1’Jabove15FN. In allcases,the FerriteNumbers of the standards shall be welldistributed over
5.1.3 The R% shall be assignedfrom TabIe2 to each
the range of interest. (see also Append~ A4.2).of the available primary thicknessstandards as definedin 2.3. For thicknessesbetweenthose givenin the table,
4.2.2 It should be recognizedthat weldmetal second-- - . -the IFNssha.llbe.interpolatedascloselyas.possibIe.Eightary standards ~e unlikely to provide readings frompoint to point that areas uniform as those from primarystandards. Care must therefore be exercised to takereadings on secondarystandards in preciselythose loca-tions used in resigningthe originalFNs to thestandards.In case of doubt, the producer of the secondary stan-dards should be consulted.
4.23 Other than the departures noted in 4.2.1 and4.2.2, the remtinder of the calibration procedure withsecondary standards shall be the same as that used withprimary standards as given in 4.1.2 through 4.1.8.
5. Calibration of Feritscopes(“~erritescopes”)
5.1 Calibration by Means of Primary Standards
5.1.1 This instrument is calibrated to the FN scaleby the manufacturer, but calibration should be vefiied
f-> by the user. The only Feritscopeq (Ferntescope) which
L../can be calibrated with primary standards according toTable 2 is the pre-1980 Model FE8-KF with analogreadout and dual-contact (“normaked~ probe. Notables for calibration with primary standards are avail-able for post-1980 instruments (those with digital read-outs or single-pole probes). Other Feritscopes may becalibrated by weld metal secondmy standards as de-scribed in Section 7.
4. Trademark of F~cher Technology. (See Appendix A6.2.)
or more thickn~s st~d~ds shall be i~d; with no~althickness corresponding to Ferrite Numbers well dis-tributed in the range Oto 25 FN (see Appendix A4.l).The instrument readingfor eachof the availableprimarystandards shall then be determined.
5.1.4 The instrument readings shall be plotted onCartesian coordinate paperversusthe FN assignedfromTable 2for eachprimary standard. A“best fit”line shallbe drawn through the data. Alternatively, a regressionequation shall be fit to the data collectedas describedin5.1.3.
5.1.5 For approved calibration, all readings shall fallwithin the maximum allowable deviations from the“best fit” line shown in Table 6. If any of the calibrationreadingsfall outsideof theseallowedvariations, the datashallbe restudied, or the manufacturer of the instrumentshall be consulted, or both.
5.1.6 The graph plotted as in 5.1.4, or a regressionequation fit to it, may nowbe used to determine the ~Sof stainless steel weld metals from the instrumentreading.
5.2 Calibration by Means of WeldMetal SecondaryStandards
5.2.1 As previouslymentioned, calibration to pri-mary stand=ds is the preferred method for suitableinstruments,but calibrationto weld metal secondarystandards is acceptable. Calibration to weld metalsecond~ standardsis necessaryfor otherFeritscopes.
Table 6Maximum AIIowable Deviation of the
—Periodic Ferrite Number ~FN) Check for Feritscopes (Ferritescopes)
Maximum Allowable Deviation of the Periodic Ferrite Number Check
From the Ferrite Number From the Ferrite Number From the Ferrite Number
VaIue Assigned to the ValueAssignedto the VaIue Fii Assignedto the
Primary Stamiqd Secondary Standard Secondary Standard
Ferrite Number Range in Table 2 by the Seller by tbe User
Otos * 0.40 m * 0.40 * 0.20
over 5 to 10 * 0.40 * 0.40 * 0.20
over 10 to 15 * 0.70 * 0.70 + ().20
over15 * 1.0 * 1.0 * 0.30
I
8
5.2.2 Refer to 7.2 for instructions to calibrate theFeritscope to weld metal secondary standards.
6. Calibration of Inspector Gages5
6.1 Calibration ByMeans of PrixnaryStandards --
6.1.1 This instrumentis the InspectorGageModelNumber111witheithera 6F (“%ferrite”)or a7F (FN)scale.The latter is preferablebecauseit has smallerdivisions.(seealSOAppendixA6.3).
6.1.2 The manufacturer’sinstructions with regard tothe use of the instrument and adjustments of the scaleshall be followed.
6.13 The FNs shall be assignedfrom Table 3 to eachof the available primary thickness standards as definedin 2.3. For thicknessesbetween those givenin the table,the FNs shall be interpolated ascloselyaspossible.Eightor more thicknessstandards shall be used, with nominalthicknessescorresponding to Ferrite Numbers well dis-tributed in the range Oto 30 FN (see Appendix A4.1).The instrument readingfor eachof the availableprinmrystandards shall then be determined.
6.1:4 The instrument readings shall be plotted onCartesian coordinate paper versusthe FN assignedfromTable 3for each primary standard. A“best fit”line shallbe drawn through the data. Alternatively, a regressionequation shall befit to the data collectedas described in6.1,3.
6.1.5 For approved calibration, all readings shall fallwithin the maximum allowable deviations from the“best fit” line shown in Table 7. If any of the calibrationreadingsfall outsideofthese allowedvariations, the datashall be restudied, or the manufacturer of the instrumentshall be consulted, or both.
5. Trademarkof ElcometerInstrumentsLtd. (SeeAppendixA6.3.)
6.1.6 The graph plotted as in 6.1.4, or a regressionequation fit to it, may now be used to determine the
3
FNS of stainless steel weld metals from the instrument J - ‘~.reading. ‘“L
6.2 Calibration by Mearts of Weld Metal SecondaryStandards- -- -- - - - ~L -:-----------
6.2.1 AS previously mentioned, calibration to pri-mary standards is the preferred method,.but c~lbrationto weld metal secondary standards is acceptable.
6.2.2 Refer to 7.2 for instructions to calibrate theInspector Gage to weld metal secondary standards.
—
7. Calibration of Other Instruments
7.1 Calibration by Means of Primary Standar&. Asofthis retilon of this standard (see3.1) ordy Magne-Gagetype instruments, Feritscopes with normalized probes,and Inspector Gagescan be calibrated to this standardby means of primary standards. All other instrumentsmust be calibrated by means of weld metal secondarystandards (seealso Append~ A6.4).
7.2 Calibration by Means of WeId Metal SecondaryStandards
7.2.1 Other instruments can be calibrated by weldmetaI secondary standards to produce a satisfactorycorrelation between the instrument readout and weldmetal FN. Whileit may be desirable that the instrumentreadout be preciselythe calibrated value of FN, this isnot essential, so long as a unique correlation betweenreadout and FN can be determined. Such instrumentsmay be used.if they have been calibrated using second-aryweldmetal standards to which FNs wereassignedbyan instrument with primary standard calibration.
7.2.2 Five or more such secondary standards arerequired for ctilbration curves covering Oto 15 ~,eight or more suchsecondary standards are required for
Table 7Maximum Allowable Deviation of the
Periodic Ferrite Number (FN) Check for inspector Gages
Maximum Allowable Deviation Ofthe Peridlc Femite Number Check
From the Ferrite Number From the Ferrite Number From the Ferrite Numb=Value Assignedto the VaIueAssignedto the Value Fti &signed to the
Primary Standard Secondary Standard Secondary s~~d
Ferrite Number Range in TabIe 3 by the Seller by the User
oto5 * 0.40 * 0.40 * 0,20
over 5 to 10 * 0.40 * 0.40 i 0.20
Over10to 15 * 0.70 * 0.70 * 0.20
over 15 * 1.0 * 1.0 * 0.30
calibration from 0 to 28 ~, and five or more suchsecondary standards are required for calibration of any
\ 30 FN interv~ above 15 FN. In all cases, the Ferrite..,;’ Numbers of the secondary standards shall be well dis-
tributed over the range of interest.
7.23 lnstmrne.nt readings shall be determined foreach of the available secondaty standards and, if possi-ble, for azero point. When taking readingson secondarystandards, the same precaution noted in 4.2.2 should betaken.
7.2.4 Instmrnent readingsshall be plotted againstassignedsecondarystandard FN valueson Cartesiancoordinate paper, and the zero point can be included ifapplicable.
7,2.5 A“best fit”smooth line shall be drawn throughthe points plotted in 7.2.4. For acceptable calibration,no data point may vary from the curve any more thanthe allowable deviations shown in Table 4. If any pointfalls outside of the appropriate allowed deviation, thedata shall be restudied, or the manufacturer of theinstrument shall be consulted, or both.
7.2.6 The graph plot~d as in 7.2.4, or a regressionequation fit to it, may now be used to determine the FNsof stainless steel weldmetals over the calibration range.
7.2.7 It is the responsibility of the user to ensure thatn% the instrument k properly ctibrated-i.e., such that the
d results obtained withweldmetal secondary standards inthe FN range(s) of use are within the expected range ofvariations shown in Table 4.
8. Use of CaKbrated Instruments8.1 Maintaining Calibration. Instruments must bechecked periodically on a regular basis against primary
or secondary standards to ensure and verifythe mainte-nance of the originalcalibration. Records ofsuch checksshall be maintained. It is the responsibility of the user tocheck at a frequency which is adequate to maintaincalibration. For frequently used instruments, a weeklycalibration check is recommended. For seldomly usedinstruments, a calibration check before each use isrecommended. Twcrstandards, one near each extreme ‘“of the calibration range being checked, shall be used foreach of the rangesshown inTables 4 and 6 through 8, asappropriate, for whichthe instrument isused, When theinstrument no Iongerproduces vaks within the maxi-mum deviation spechled in the relevant table, it shall beremoved from service and the manufacturer shall beconsulted. (seeAppendix A3.2).
8.2 Variations in Measurements. Based upon roundrobin tests within the Welding Research Council Sub-committee on Welding Stainless Steels, the FNs deter-mined by these instruments are expected to fall withinthe limits shown in Table 9,10, or 11as compared to theoverall averageFN values of stainless steel weld metalschecked on other instruments of the same type cali-brated to this standard. When measurements are madewith a variety of calibrated instrument types, somewhatIargervariation in measurementsthan those indicated inTable 9,10, or 11might be expected, but the magnitudeof the variation has not been determined. Weld ripplesand other surface perturbations must be removedbecause surface ftih affects measurement accuracy.Up to about 20 FN, the practice known as “draw ftig”produces acceptable accuracy (see 2.2). For accurateand reproducible ferrite measurements, above 20 FN, aMagne-Gage No. 3 magnet or equivalent requires a flatsurface at least 1/8-in. (3.2mm) in diameter fdhed nocoarserthan with a 600grit abrasive[about 8microinches(0.2 microns) RMS]. Rougher surfaces or convex sur-
Table 8Maximum Allowable Deviation of the
Periodic Ferrite Number (FN) Check for Magne-Gage-Type Instruments
— Maximum MIowable Deviation of the Periodic Ferrite Number Cheek
From the Ferrite Number From the Ferrite Number From the Ferrite NumberValue Assignedto the Value Assignedto the Vatue Fii Assignedto the
Primary Standard !jecondarySti~d Secondary Standard
Ferrite Number Range in Table 1 by the Seller by the User
oto5 * 0.50 .’ * 0.50 * 0.20over 5 to 10 * 0.50 * 0.50 * 0.20over 10to 15 * 0.60 * 0.60 &().3()
over15to 25 &0.80 * 0.80 * 0.40over25 [0 90 &5% of sssigned 3 5%of imigned &MOof assigned
FN value FN value FN value
—
10
Table 9Expected Range of Variation
in Measurements with CalibratedMagne-Gage-Type Instruments’
Ferrite Number 67%of the 9597Jof theRange Instrument” “ Instruments
o to 10 * 0.30FN * 0.60FNover10 to 18 * 0.35FN * 0.70FNover18to 25 * 0.45FN * 0.90FNover25to 90 * 5T0 of mean * 10%of me~
FN value FN value
●BaseduponWRCround robintests.
Table 10Expected Range of Variation
in Measurements with CalibratedFeritscopes (Ferritescopes)’
Ferrite Number 67%of the 95% of theRange Instruments Ir@ruments
o to 10 * 0.20FN * 0.40FNover10to 18 * 0.4JIFN * 0.80 FNover 18 to 25 * 0.50 m * 1.0 FNover 25 to 80 * 59?0of mean * 10910of me~
FN value FN value
*Based upon WRCroundrobhtests.
faceswill result in artificiallylow FN valuesand shall beavoided. Other instruments may respond differently torough, convex, or narrow surfacesand should be exam-ined fully before use. At all ferrite levels,surface prepa-ration must be accomplishedwithout contamination byferromagnetic materials.
Table 11Expected Range of Variation
in Measurements with CalibratedInspector Gages*
FerriteNumber 67%of the 95% of theRange Instruments timents
o to 10 * 0.20 FN * 0.40 FNover 10to 18 * 0.40 FN * 0.80 FNover 18to 30 * 0.50 FN * 1.0FN
*BaseduponWC roundrobintests.
9.
9.1
.—
Significant Figures in IleportingMeasurement Results
Calibration Data. For purposes of developing cal-ibration data or demonstrating compliance of aninstrument with calibration requirements, the numberof si@lcant figuresshown in the relevant Table hereinshall be used.
9.2 Measurement Data. For purposes of reportingmeasurementdata on weldmetal test samplesor demon-strating compliancewith the requirements of asptilm-tion other than this specifkatio~ the preckion impliedby the number of signiilcant figures in the Tables hereinis generally inappropriate. For ferrite measurements of25 FN or higher, rounding off to the nearest wholenumber conveys appropriate precision. For ferritemeasurement of 5 to 25 FN, rounding off to the nearest0.5 F’Nconveysappropriate preeidon. For ferrite mea-surements less than 5 FN, roundiig off~o the nearest0.1 FN conveysappropriate rmcision..
—
3$’\.: ‘ ;
m~<- ; .7,,
,,. .,%.. T“—— ,,, -.. .!. .-~ ,,, - . . . .. . ‘.. A$=- /.-%* ,., z- ~ -=-z=-7-.T-zz?rrnz?’T .. , ‘“X.7.,..:- ~~ — —-. . .
\ .,,;’
Appendix .-. .. .(This Ap~endix isnot apart of ANSI/ AWSA4.2-91,Standard ~oceduresfor Calibrating Magnetic Instruments to
Measure the Delta Ferrite Content of Austenitic and Duplex Au.stenitic-Ferritic Stainless Steel Weld Metal, but is
included for information purposes oniy.)
AL Acknowledgment
Thesestandard proceduresare basedupon the studiesand recommendations made by the Subcommittee onWelding Stainless Steel of the High AUoysCommitteeof the Welding Research Council (WRC)$ The docu-ment on which most of this standard is based is the
- Calibration l+ocedure for Inmurnents to Measure the
Deha Fem”te Content of Austenitic StainlessSteel Weld
Metal, published by the WRC on July 1,1972.Expansion of the measurement systembeyond 28 FN
?is based upon &tension of the WRC Ferrite Number
J1: System, D. J. Kotecki, Welding Journal, November,
., 1982and International Institute of WeldingDocuments11-C-730-84,II-C-821-88,II-C-835-88and II-C-836-88.
A2. Ways of Expressing Ferrite ContentA2.1 The methods of determining ferrite content instairdesssteelweldmetal haveevolvedoveran extendedtime period. The interested reader is referred to WRCBulletin 318 (September, 1986).Only a few of the perti-nent conclusions of that Bulletin are summarized brieflyin the following paragraphs.
A2.2 MeasuredPercentFerrite.The pereentferrite inausteniticstirdess steelweldmetalsin the pasthas toooften been regardedas a fm fwed value. Extensiveround robins have been run onsets o~weldmetal speei--.rnens, contifig up to a nominal 25 percent ferrite, inthe U.S. under the sponsorship of the WRC and onsimilar sets in Europe by the International Institute ofWelding (w. These round robins showed that mostlaboratories used somewhat different calibration curvesas weUas a variety of instruments. At nohal levelsofup to 10 percent ferrite, which is often the most useful
((...! 6.WeldingResearchCouncil,345East47th St., NewYorkNY10017.
and pertinent range, the values obtained by participat-ing laboratories ranged from 0.6 to 1.6times the nomin-al value.The instrument calibration procedure definedin this standard is designedto overcome this problem.
A similar problem existedwith metallographic deter-minations due to the extreme fineness of the ferrite inweld metrds, variations in the etching media and thedegreeofetch,and to the Quantitative TelevisionMicro-scope (QTM) settings, if a QTM was used. Similarproblems, though perhaps to a lesser degree,have beenencounteredwith magneticsaturation, x-ray diffraction,Mossbauerstudies, and with other methods ofdetermin-ing the ferrite content of weld metals. Thus a “percentferrite” figure in past literature is very dependent uponthe source, and shotdd be defined in relation to theinstrument, the laboratory using i~ and the calibrationsource, or to the diagram if derived from a constitutiondiagram. In the opinion of the WRC Subcommittee, ithas beenirnpossibIe,to date, to determine accuratelythetrue absoluteferritecontent ofstainlesssteelweldmetals.
A2.3 Ferrite Number. Beeause on a given specimen,laboratory A might rate the percent ferrite at as low as3 percen~laboratory Bat 5 percen~ and laboratory C atashigh as 8percen~ the WRC Subcommittee deeidedtouse the new term Fern-te Number (FN) to define theferrite quantity as measured by instruments calibratedwith its recommended procedure. Thus, FN is an arbi-trary, standardized value related to the ferritecontent ofan equivalentlymagneticweldmetal. It is not necess@Ythe true absolute ferrite percentage of the weld. INbelow 10do represent an exceUentaverage of the “per-cent ferrite” as determined by U.S. and world methodsof measuring deha ferrite, based upon the previouslydiscussed round robins conducted by the WRC Sub-committee and the IIW Subcommission II-C. FNsabove 10clearly exceed the true volume pereent. Mag-netic sawtion measurements on c~tings of knownpereentferritehave shown that the magnetic responseofa givenpercent ferrite depends upon its composition. So
I
,,--. ,.., .,-.~.,-.,-, ,. ...,.,.! ..~ ,,. , , , ,
-.,-. . . . ., . . . .
, -. ,.. s-—xm? .. - .— _—. . . _______
12
any relation between percent ferrite and FN wiU beinfluencedsomewhat by composition of the ferrite. Forcommon duplex amtenic-ferntic weld metals, it is notunreasonable to estimatethat the percentferrite is on theorder of 0.7 times the FN as measured herein, but thisshould not be considered as exact.
A2.4 Ferrite content calculated From ConstitutionDiagrams. The several committees that have investi-gated and reviewed this subject recommend for mostapplications the me of measured ferrite as opposed tothe use offerrite calculatedfrom the weldmetal analysis.The basic re=on for this is that the variablesinvolvedindetermining the chemicalcompositio~ and other vtuia-bles involved in the diagrams themselves,are very likelyto have substantially greater effects than those asso-ciated with the direct determination of ferrite contentusing instruments calibrated in accordance with thisstandard. Nevertheless,constitution diagrams are veryuseful took, even though they are less exact becausethey permit anticipat~.onor prediction of ferrite contentfor a variety of situations. By taking into account dilu-tion effects,such diagrams can also be useful for antici-pating or predicting the ferrite content of weld overlaysand d~similar metaljoints.
The Schaeffler diagram, developed in the late 1940s,presentsits values as percent ferrite, but these are said tobe directly equivalent to FNs. The DeLong dia~January 1973version,was the fmt diagram presented interms of FN. ESPY,in 1982,proposed a modifkation ofthe SchaeffIerDiagram to take into account high nitro-gen, high manganese stainless steel weld metals. Themore recent diagram of Siewert, McCowan, and Olson,prepared under WRC sponsorship in 1988, is, at thetime of this writing, the best estimation tool availableformost austenhic and duplex austenitic-ferntic stainIesssteelweldmet~. See WeldingJournal, December, 1988,pp. 289s-298s, or WRC Bulletin 342, Apfi 1989.Toassist @ Ferrite Number estimation, a Personal Com-puter software package, FERRITEPREDICTO% isavailablefrom the AmericanWeldingSociety,althoughjat the time of this writing, only the Schaeffler andDeLong Diagrams are included.
A3. Cautions on the Use of FerriteNumber
A3.1 Instmment Cali.iration
A3.1.l Various thicknesses of nonma~etic materialovercarbon steelrepresent a veryconvenient method ofcalibratinginstruments for the measurement offerrite instainless steel weld metals. Useful general informationon the subject can be obtained from the latest editionof The American Society for Testing and MateriaIs
Coating 27zicknessesbyMagneticMetho&Nonmagnetic
Coatings on Magnetic Bare Metak? The response of theinstrument when a nonmagnetic ‘skin” is between themeasuring probe and the plate, versus its response toferrite in stainless steel weld metal at several levels, can
. be plotted and the relationship _be~weenthem estab-lished. A chkge in the magnetsiz~or stren-~h, Or% the’probe characteristics, changes the relatiomtip. llms, acalibration curve or table for FN ve~~ nonmagneticcoating thickness for a Magne-Gage-type instrument(Figure AI) wi.11be different for each of the magnets(Nos. 1,2,3 and 4)because the strengths of the magnetsare different.
A3.L2 With Magne-Gage-type instruments, onlycalibration using a No. 3 magnet is considered in this
standard. A weakermagnet (No. I or No. 2), ifused withthe calibration points ofTabIe 1,willon weldmetaIyieldfalsely high FN values. Conversely, a stronger magnet(No. 4), if used with the calibration points of Table 1,will on weld metal yield falsely low FN values. IftheNo.3 magnet of a Magne-Gage is damaged, such as byrough handling or exposure to an ac field which weak-ens ic it will also yield false readings. Work within theWRC Subcommittee on Welding Stainless Steel, onbehalf of the International Institute of Welding, Sub-commission II-C, has demonstrated that accurate read-ings on weld metal are obtained via calibration fromTable 1when the magnet strength is such that it providesa tearing-off force as a function of FN of 5 FN/grarn&O.5 l?N/ gram. Whh a torsion balance other than aMagne-Gage, compliance with this requirement is deter-mined d~ectly from the slope of the calibration line.With a Magne-Gage, this can be evaluated simplY bysuspending a 5 gram iron weight from the NO. 3 magnet.When the white dial of the Magne-Gage is turned to justbarely lift the weight past the balance point of theinstrument, the reading should correspond to 25 FN*2.5 FN uing the crdibration line of whitedial readingsversus FN.
A3S3 It is strongly recommended that referenceweld metal secondary standards be used along with thecalibration curves obtained from primary standardswhen using a Feritscope to check for compliance withTable 6, when using an Inspector Gage to check forcompliancewith Table 7, or when using a Magne-Gagetype instrument to checkfor compliancewith Table 8. Ifcomphnce cannot be obtained as required by theappropriate table, the instrument is in need of recalibra-tion orservicingbytie manufacturer, or it is not suitablefor calibration with primary standards.
‘1;“ “>“,.
1( .“‘:!5”, ..
J..
7. ASTM standards can be obtained from the Pmefican ‘:-Societyfor Testingand Materials, 1916Race Streetj Philadel- J
(ASTM) B499, Standard-Method for ‘Meartuement of p~~ PA 19103. I
I
A3.2 Instrument Malfunction. Recalibration or re- SRM 1321,Nominal Thicknesses— 1.34,1.46,1.65,--- .-.checking of each instmment at periodic and sometimes and 1.85 roils (.034, .037, .042, and .047 mm,frequent intervals is necessa~ to ensure that the instru- respectively).ment is operating properly(see8.1).Permanent magnets The sets can be ordered from NIST. Other thicknessmay be partially demagnetized by exposure to any sig- sets are rdso available, but do not, of themselves,offernificant ac field such as that generated by a strongalternating current in a wire or by a weaker alternating
closeenough spacingofcorresponding Ferrite Numbersfor adequate calibration..
current in acoil. The tiPsofsuch IIermanentmamets; or..... .:=-—--—---’- - - -. - - --- - .=-- ==.==. .. =— ._—-—
of the probes wtich areused to es~abliiha magn~ticfieldin the speeimen, ~ay become worn and the response ofthe system may change for th~ reason. Bearings maybecome fouled Withdirt ~d thus fail to operate freeIy.
A4. Standards for InstrumentCalibration
A4.1 Primary Standards. NIST8 coating thicknessstandards were developed many years ago to calibrateinstruments for the determination of coating thickness.The stand=ds useful for the determination of deltaferrite consist of Varyingthicknesses of copper electro-plated on a carbon steel base and protected with achromium flash. NIST certiiies the thicknessof the totalcoating to within *5qo of the stated thickness, but themajority willbe within* 270or even* 1’ZO.ne~e of tietwo sets listed belowis recommended for calibration upto 28 FN.
SRM 1363ANominal Thicknesses-9.6, 16,20, and26 roils
SRM 1364ANominal Thicknesses-32, 39,59, and79 roils
These 8 thicknesses corresp~d nominally to 0.26,0.39,0.50,0.64,0.80, 1.00, 1.53, and 1.94mmj respec-tively.
Sets SRM 1368 (8 to 20 roils), SRM 1369 (25 to60 rnils) and individual standards are no longer avail-able. The-8 mil thickness is now available in set SRM1362A..
For Ferrite Numbers from about 30 to about 85, theuse of the three sets listed below is recommended forcalibration
SRM 1323,NominaiThicknesses -3.7, 4.4,5.3, and6.6 nils (.094,.1 12,.135, and .167 mm, respectively).
SRiM 1322,Nomiual Thicknesses-2.1, 2.4,2.7, and3.2 rnils (.053, .060,.069, and .080 mm, respectively).
8. Office of Standard Reference Materials, Room B311,ChemistryBuilding,National hstitute of Standards andTeeh-nology (formerly National Bureau of Standards), Gaithers-burg,MD 20899,Phone301-975-6776.
A4.2 Secondary Standards
A4.2.1 WeldMetalSecondaryStandards. Magneticinstrumentsmayalsobecalibratedbyusingweldmetalsecondarystandardspreparedfrom weldmetalsratedby 2 or moreinstrumentscarefullycalibratedthroughthe use of thesestandardprocedures.Each suchstan-dard should be providedwith FN values at spec~lcpointsonitstestsurface.Thesesecondarystandardscanbeusedforthecfllbrationofasuitableinstrumentorformaintainingcalibration.Theycanalsobeusedtoestab-lish the relationshipbetweenother instruments andMagne-Gage-typeinstruments.
A4.2-2 Otier Types of Secondary Standards. Theuse of cast specimens or powder compacts is riskybecause the size,shape, and orientation of the magneticparticles may influencethe response of the magnetic orother type probes to varying degsees. However, castspecimens or powder compacts calibrated with oneinstrument traceable to this procedure can be used forcalibrating instruments of the same type and manufac-ture or for day-to-day verification of such instruments.
A5. Effect of Ferrite Size, Shape, and, Orientation
It has been established that the ferrite size,shape, andorientation can influencethe relative response of the lowfieldstrength magnets and probes tied with the measur-ing instruments. For this reason, a measuring instru-ment may respond dtierentiy to a givenvolume percentferrite in a stainlesssteelweld metal as compared to thesame volume percent ferrite in a cast stainIess steel, orevenin a solution heat treated stainless steelweldmetal.The ferrite in as-weldedweId metal up to about 15FNis very fme and in the form of lacy, dendritic stringersgenerdy perpenditi~ to the fuion Line,and oftenextensivelyintercomected at ferrite contents over 3 or4 FN. Above about 15FN in as-welded weld metal, theferrite and austenite generallyform laths which are aIsovery free. The ferrite ‘mcastings is usually much largerand tends to be more spheroidal and much less inter-connected except perhaps at very high ferrite contents.The ferrite in wrought steelsand insolutionheat-treatedweld metals tends to be lesser in volume and morespheroidtied than in an as-welded weld metal of thesame composition because heat treatment tends to
14
transform some ferrite to austenite and spheroidize the metal in terms of FN. As of 1989,the ability of Inspectorbalance. Since thevolumepercentofferrite in castings is Gages to determine ferrite above 30 ~ is U&om. _
in close agreementwhenmeasuredby eithermagnetic \3
..-:“responseor by metallographicpoint count, the ferrite A6.4 OtherInstruments .,.. “contentof castingsisexpressedasa percentageandnot
x...A6.4S Thefollowinginstrumentsat the timeof the
by the arbitrary~, asnotedin ASTMPracticeA800.. -- _@ng ofthis revisionare not capableof being@i-
A6. Instruments
A6.1Magne-Gageand MagneGag-Type Instmments
A6.1.1 The Magne-Gage9(Figure Al) is usable onlyin the flat position on relatively small specimens. Theprobe is along, thin magnet hung on aspiralspring. Thespring is wound by means of turning a knob with acorresponding reading on a dial. When the magnet ispulled free of a specimen,the white dizdreading used inconjunction with the cdbration curve establishes theFN of the specimen.
A6.L2 Returning the Magne-Gage periodically tothe factory for maintenanceisdesirable.With heavyuse,1year is a reasonable tiiq with light use, 2 years.
A6.L3 A Magne-GageNumber 3 Magnet or equiv-alent can be used with a variety of torsion balances toobtain the same results as are obtained with a Magne-Gage. A compIeteexample of such a Magne-Gage-typeinstrument is given in “Extension of the WRC FerriteNumber System” referencedin Section Al. Numerousother con.figuration could also be conceived. This isoutside the scope of this Standard.
A6.2Feritscopel”(Ferntescope). This instrumen~ con-sisting of a probe connected by a cable to an electronicspackage (Figure X2), is usable in any position. Severalmodels and a variety of probes are avaiIable.Only onemodel and probe has been shown to be able to becalibrated with primary standards as given in TabIe 2(see5.1.1).All others must be calibrated with weldmetrdsecondary standards. Models are availablein either bat-tery powered or ac current versions. At least one modelcan becdlbrated withsecondarystandards up to 80FN.
A6.3 Inspedor Gage.” This instrument (Figure A3), isusable in any position. It is a hand held magneticinstrument with thumb actuated springs tension. Theinstrument gives direct readings in FN if it is a newmodel designed to do so. Older models can be rebuilt bythe manufacturer to give acceptable readings on weld
brated to primaly standards. Tiley ~ however,’be”calibrated to weld metal secondary standards and pro-duce acceptable consistent results. Again, itis theresponsibility of the user to ensure that instrument calib-ration is maintained and to have the instrumentrepaired by the manufacturer if consistent readings onthe weldmetal secondarystandards cannot be obtained.As of 1989,the ability of these instruments to determineferrite above 30 FN is unknown.
A6.4.1.1 Ferrite Indicator (more commonly calleda Severn Gage).’*This instrument (Figure A4) isusablein any position. It is a go-, no-go-type gagewhichdeter-mineswhether the ferritecontent is above or beloweachof a number of inserts of various magnetic strengthswhichcomew-hhtheinstrument. Atleast oneunthreadecLtest insert must be available for use in conjunction withone of the threaded insertswith specifiedFNvalues. Thepurpose of the unthreaded inserts is to asure that themagnet has not lost strength. Details may be obtainedfrom the manufacturer for convemion of percent ferritevalues on earlier model Severe gages to FN. Severegages calibrated d~ectly in terms of FTNare now availa-ble. Older model gages can be converted to the FNscale by the manufacturer.
A6.4.1.2 Foerster Ferrite Content Meter}3 This isa ligh~ portable, battery-operated instrument (F@ueM) usable in any position. It ‘closely resembles theFeritscope in its operation except that it has a singlecontact point probe which allows ferrite determinationin very localized regions. On older models, the meteroutput indicates ferrite content as a percentage, whichcan be effectivelyconverted to FN values by the use ofsuitable weld metal secondary standards to produce asatisfactory calibration me. Newer models are nowavailabIe on which the meter reads directly in I?Nvalues.—
A6.4.2 A number of other magnetic measuring fitru-ments are available for various purposes. Many areregarded as not suitable in their present form because oflimitations such as range, problems in calibration, orvarying response due to the position of use or to theirrelation to the north-to-south magnetic field lines of the
-. -
9. Manufactured by Magne-Gage Saks & Senfice, 14376Dorsey MU Road, Glenwood, MD 21738.10. Manufactured by Fiicher Technology, 750 Marsh~Phelps Road, Windsor, CT 06095.11. Manufactured by Elcometer Instruments Ltd., 1180EastBig Beaver,Troy, MI 48083.
12 Manufactured by Severe Engineering Co., Inc., 98 Edge-wood StreeL Annapolis, MD 21401.13. Marketed by Foerwer Instrument Inc., 202 RosemontDr., COmOPOlk,PA 15108. I
/,((-j~,,..’
..— ,-—
:.,-;, ,,:.
..---,.
..: .....:,,j”,-;;:; ~’~:7 .,+,. . “,,.y. .... ..
0 “1,::. ..
,, ,,. .;. . .:,, ~,..::,
.,
.-
(A) STANDARD MAGNE-GAGE
. .
(B) MAGNE-GAGE FROM REAR. COUNTERWEIGHTADDED TO LEFT SIDE OF BALANCE BEAM
Figure Al- Ma~eGage-TYPe -menti
16
---,.-:
. .,— --- .—. — .-.-.— ---
(c) TORSION BAIANCE WITH MAGNE-GAGE NO. 3 MAGNIZr
Figure Al (Continued) — Magne-Gage-Type Instruments9.; ‘:).:.. /-.
.. .. ...;:-kr.,:-.,y “ := -T- . .,
. - ;.. -7. --~:. (“”.”.“:.T ,“.,-. . . . ., .,
J.... .b
Figure A2 —Ferritticope
._.T----YZ7 -- ‘-=”.,, =-7..-. ,+< . .: . “1!.,. , . . .. ,.,, m — —.,-.. . . . . ecr-c---- , T-C-7-7,., - ______ . . .,, _. _—____ . . . . ._
Figure A3 —Inspector Gage
-.
.
F@re A4 - Ferrite Indicator (Severn Gage)
.-.— — ...
. --
Gi3w
... . ,,..<J7,-V ...... .,, ..-TT-r-- . T----’ZX,>8 .-$ ‘ <...,.. >-s.. _. ._, -.y-,.............. . ... -T--- . . ..-, ——
18
Figure A5 —Foerster Ferrite Content Meter
earth. One that setms promising is the FerntectorGageJ4Instrumentswhicharesuitableinotherrespectsmust still be calibratedto the FN scalein a mannertraceableto thisstandard.Thiscanbe accomplishedbythe use of a set of 5 or more weld metal secondarystandardsif the calibrationisextendedup to 15FN, or8 or more if it isUpto 25FN. The establishmentof anadequatecorrelationis the responsibilityof the user.
A7. Use of Calibrated InstrumentsA7.1Dki@ce for Ferromagnetic MateriaL The FNvalues of stainless steel weld deposits on ferromagneticbase metal may be increasedby varying degreeson eachinstrument depending on the distance of the magnet orprobe from the basemetal, on the ferritecontent, and onthe permeability of the base metal. Hence, to limit theincrease in I?Nvalues to 0.2 FN maximum due to theeffect of a ferromagnetic carbon steel base metal, thecarbon steel base plate should be approximately 0.3 in.(8 mm) or more away from a Magne-Gage magnet orInspector Gage magnet, LOin. (25 mm) from a Ferrite
14. Manufactured by Elcometer Instruments Ltd., 1180EastBigBeaver,Troy, MI 48083.
Indicator (SevernGage),and 0.2 in. (5 mm) from aFeritscopeor Foerster Ferrite Content Meter probe.For other instruments,a safedistancecan be obtainedby experimentationor by contacting the instrumentmanufacturer.If it is not possibieto obtain the aboveminimumdistancesfrom ferromagneticmaterial in aproduction situatiou FN measurementscan still bemeaningfulif the effectof the proximityof the ferro-magneticCm be taken into account. One way to dothis is by comparingl?hJmeasuredwith ferromagneticmaterial in placeto FN measuredwith ferromagneticmaterialremovedusinglaboratorysamples.
A7.2 Wrought Stainless Steels. It is not intended thatthe determination of FN be extended to wrought stain-less steels. Wrought steels are beyond the scope of thisstandard.
A73 CA Stainless Steels. The FNS are not used forcast sttiess steels.The same measurement scalesusedfor weldmetals cannot be used for cast steels(seeA5foran explanation). To calibrate instruments for measuringthe ferrite content of cast stainless steels, obtain ASTMA799, Standard Practice for Cal&ration Instrumentsfor EMmating Ferrite Content of Cast Stainless Steels.
Equally useful will be ASTM A800, Stan&d Practicefor Estimating Fem”te Content in Austenitic AI~oYCustings.
3...-J
ACKNOWLEDGEMENTS
The author wishes to thank the following individuals, whose contributions
significantly assisted in the completion of this study and my academic degree. Gratitude
is expressed to the members of the Materials Joining Research Group, Wei Liu, Peng Liu,
Songqing Wen and Mark L. Morrison, whose invaluable assistance was greatly
appreciated.
Sincere gratitude is expressed to Mr. Malcolm Blair, Vice President of the Steel
Founders’ Society and Dr. Darnian Kotecki (Lincoln Electric Company) for their
continued commitment to academia and research. Appreciation is expressed to Mr. Frank
Lake (ESAB), Mr. Sushd Jana (Hobart Brothers Co.), Dr. Tom Siewert (NEST), Mr. Joel
Feldstein (Foster Wheeler, Inc.), Mr. Ron Bird (Stainless Foundry Inc.) and Mr. Chris
Richards (Fristam Pumps) for their participation in the round-robin test series.
Lastly, I would like to thank the Department of Energy, the South Carolina
Research Authority and the Universi~ of Tennessee for their guidance and support.