inclusion rating of steels as per astm standads
DESCRIPTION
Inclusion rating of steels as per ASTM standads. All procedure and comparison charts are provided.TRANSCRIPT
INCLUSION RATING IN STEELS AS PER ASTM STANDARDS
MUHAMMED LABEEB
13MY06
INCLUSIONS
▪ Inclusions are non metallic particles embedded in the steel matrix.
▪ Chemical compounds of metals like (Fe, Mn, Al, Si, Ca etc) with non metals (O,
S, N, C, H)
▪ Examples: SiO2,MnO,MgS,Ce2S3,AlN etc…
▪ Properties: An inclusion is a mismatch with the steel matrix. Both may have
different properties resulting in undesired effect.
INCLUSION RATING
▪ Standard reference charts depicting a series of typical inclusion configurations
(size, type, and number) were created for direct comparison with the microscopic
field of view
▪ Rating is done in comparison with the ASTM standard chart. [Designation: E 45]
▪ Inclusions are assigned to a category based on similarities in morphology, that is,
by size, shape, concentration, and distribution, and not necessarily on their
chemical identity
CLASSIFICATION OF INCLUSIONS
▪ Inclusions are classified into four categories (called Type) based on their
morphology
▪ Each of them are classified into two subcategories based on their width or
diameter
CLASSIFICATION OF INCLUSIONS
categories
A-Sulfide Type
heavy
thin
B-Alumina Type
heavy
thin
C-Silicate Type
heavy
thin
D-Globular Oxide Type
heavy
thin
• Although the categories contain chemical names that imply knowledge of their chemical content, the ratings are based strictly on morphology
• The four categories, or Types, are partitioned into Severity Levels based on the number or length of the particles present in a 0.50 mm2 field of view
CLASSIFICATION OF INCLUSIONS
▪ Type A and C inclusions are very similar in size and shape
▪ They are distinguished based on their colour when viewed under brightfield illumination
▪ Type A-Sulfide are light gray
▪ Type C-Silicate are black
▪ The B-type stringers consist of a number (at least three) of round or angular oxide particles
with aspect ratios less than 2 that are aligned nearly parallel to the deformation axis
▪ The D-type are globular in shape
PROCEDURE
▪ The minimum polished surface area of a specimen for the microscopic
determination of inclusion content is 160 mm2 (0.25 in.2)
▪ Field of view is 0.50 mm2 or square of side 0.71 mm
▪ Either of two techniques may be employed to achieve a
0.50 mm2 field of view
▪ One method is to project the microscope image onto a viewing screen that has a
square mask with 71.0 mm sides drawn on it
▪ Another option is to use a reticle made for the microscope, which will superimpose the
required square mask directly onto the field of view
PROCEDURE
▪ Inclusions are classified into the before mentioned four types
▪ After the inclusions are categorized by Type, they must be categorized by thickness
or diameter- thin and heavy series
▪ After classification by type and thickness, the severity levels are determined for the
inclusions comparing with the chart
▪ These values can be numerically calculated as length or number based on the
limits given in standard Table (given below)
COMPARISON CHART- A (Sulfide type)
COMPARISON CHART- B (Aluminate type)
COMPARISON CHART- C (Silicate type)
COMPARISON CHART- D (Globular type oxides)
PROCEDURE
REFERENCES
▪ R E SMALLMAN – Modern Physical Metallurgy and Materials Engineering
▪ P C ANGELO – Materials Characterization
▪ ASTM E 45 – 05 - Standard Test Methods for Determining the Inclusion Content
of Steel
▪ ASTM E 1245 - Practice for Determining Inclusion or Second-Phase Constituent
Content of Metals by Automatic Image Analysis