demoversion iwe 2011

8/21/2019 Demoversion IWE 2011

1/47

The Welding EngineersCurrent Knowledge

Edition 2011 GSI 2011

Welding processes and equipment

Materials and their behaviour during welding

Construction and design

PART 1


Materials and their behaviour during welding


Fabrication, applications engineering

PART 3


2/47

PART 1

2010 SLV Duisburg Branch of GSI mbH

Copyright by SLV Duisburg. All rights reserved

International Welding Engineer (IWE)

Course according to IIW Guideline IAB-252-07

Member of DVS - Deutscher Verband fr Schweien

und verwandte Verfahren e.V. (German Welding Society)


3/47

International Welding Engineer (IWE)Part 1




Expert Guidance:

Dr.-Ing. Winkler

The Document contains standards reproduced by permission of DIN Deutsches Institut fr Normung e.V.The definitive version for the imple-mentation of this standard is the edition bearing the most recent date of issue, obtainable from Beuth Verlag GmbH, Burggrafenstrasse 6,D-10787 Berlin.


4/47

Theoretical education Part 1



Modul 1: Welding processes and equipment

Chapter Subject

1.01 General introduction to weldingtechnology

1.02 Oxy-gas welding and related processes

1.03 Electrotechnics a review

1.04 The arc

1.05 Power sources for arc welding

1.06 Introduction to gas shielded arc welding

1.07 TIG welding

1.08 MIG / MAG and flux cored arc welding

1.09 MMA welding

1.10 Submerged arc welding

1.13 Cutting and other edge preparation processes


5/47

Oxy-gas welding and relatedprocesses I

IWE-1 / 1.02Page 5

Eisenbeis 2010 SLV Duisburg Branch of GSI mbH Welding processes and equipment


Fig. 5: Oxygen supply by cold gasifier

Vacant air-vaporizer

Air-vaporizer are used for evaporation of deep-cold liquid gases. They are working energy independentand non-polluting. The liquid of the cold gasifier will be evaporated by the following air-vaporizer and willget into a tube system to the place of consumption.

The vaporizer output will be influenced by

the sort of gas the ambient conditions at the location

the output temperature of the gas

the duration of operation

A protection against cold embrittlement is a security-system to prevent a lower temperature as the al-lowed gas-temperature. This protection is available in different types.

In case of a fall short of the approved temperature either a magnetic valve will close the gas tube and, atthe same time, an acoustical signal will be heard or a valve will throttle the cross-section of the tube.


6/47

The arc I and IIIWE-1

1.04-1 / 1.04-2Page 1

Eisenbeis 2010 SLV Duisburg Branch of GSI mbH Welding processes and equipment


1. General procedures during arc welding

1.1 Fundamental structure

The stick electrode is an arc-producing electrode and a filler metal at the same time. The stick electrodeillustrated in Fig. 1 consists of a metal core stick which is surrounded by a cover consisting of alloyingelements and consumables. During welding with DC the polarisation is related to the electrode.The current between electrode and molten bath is conducted in the form of an arc. The resistance heatis used to melt the filler metal and the ground metal. A shieldgas atmosphere is formed by combustion ofthe consumables. The shield gas atmosphere protects the arc and the molten pool against atmosphericcomponents (e.g. O2, H2, N2)

drop transfer ofmetal and slag

covered electrode

covering

core wire

arc

molten pool

slag

weld deposit(base and filler metal)

workpiece

(base metal)

flux covering

Figure 1:Frequently used terms (metal arc welding)

1.2 Charged particles in the arc area

anode (+)

cathode (-)

+++++

-----

electrons(current)

positive gas ions

Fig. 2 describes the flow direction of thecharged particles between anode andcathode. Beside a high amount of elec-trons with a negative charge moving from

the cathode to the anode, anions e.g. OH-

- ions are floating in the same direction.Ions with a positive charge (cations) e.g.

Fe+

-or H+

-ions are moving to the nega-

tive pole.

Figure 2:Flow direction of the charged particles during arc welding


7/47

TIG welding I IWE-1 / 1.07-1Page 1

Bltmann 2010 SLV Duisburg Branch of GSI mbH Welding processes and equipment


Alternative names: Tungsten Inert-Gas (TIG) welding; gas tungsten arc welding (GTAW), Argonarcwelding

Type of operation: Manual, MechanisedHeat source: Arc

Shielding: Inert gasCurrent range: 10 to 500 A

Mode of operation: An arc is established between the end of a tungsten electrode and the parent metalat the joint line. The electrode is not melted and the welder keeps the arc gap constant. The current iscontrolled by the power-supply unit. A filler metal, usually available in 1 m lengths of wire, can be addedto the leading edge of the pool as required. The molten pool is shielded by an inert gas which replacesthe air in the arc area. Argon and helium are the most commonly used shielding gases.

Typical applications: High-quality welds in metals such as aluminium, stainless steels, nimonic alloys andcopper in chemical plants; sheet work in aircraft engines and structures;Mainly thin sheets.

Figure:Principle of the tungsten inert-gas welding processes

Figure:Schematic of a TIG-welding system Characteristic of power source and arc


8/47




Materials and their behaviour duringwelding

Expert Guidance:

Dipl.-Ing. Holthaus


9/47

Theoretical education Part 1



Modul 2: Materials and their behaviour during welding

Chapter Subject

2.01 Manufacture and designation of steels

2.02 Testing materials and the weld joint

2.03 Structure and properties of pure metals

2.04 Alloys and phase diagrams

2.05 Iron carbon alloys

2.06 Heat treatment of base materials and welded joints

2.07 Structure of the welded joint

2.08 Plain carbon and carbon-manganese steels

2.09 Fine - grained steels

2.10 Thermomechanically controlled process steels (TMCP-steels)

2.11 Cracking phenomena in welded joints


10/47

Structure and properties ofpure metals I

IWE-1 / 2.03-1Page 2

2010 SLV Duisburg Branch of GSI mbH Materials and their behaviourduring welding


The bonding forces are attraction forces between opposed electrical charges. It is essentially distin-guished between three types of bondings:

Ionic bonding: It relies on an exchange of electrons of the individual elements where one has anouter atomic shell filled to a large extent, the other one slightly filled only.

Atomic bonding: The atoms form common pairs of electrons from their valence electrons in order tofill up their outer shell. The positively charged atomic residues are held together. These can be one(Cl2), two (O2), or three (N2) common atomic pairs.

Metallic bonding: Elements with a small number of valence electrons deliver them as a uniformlydistributed, free movable electron cloud. The valence electrons thus remain in the bond and hold thepositive metal cations together.

Figure 1:The bonding types of solid bodies


11/47

Iron carbon alloys Il IWE-1 / 2.05-2Page 4



Sulphur can only in small amounts be dissolved in steel and can often be regarded as insoluble. To-gether with iron and oxygen it forms low melting eutectica that in high temperature ranges (over approx.950C) lead to the formation of hot cracks and at temperatures about 800C they are susceptible to brit-tle fracture (red shortness).

Sulphur segregates in unkilled steels and concentrates in the centre.

Due to this reason, sulphur is unwanted in steels and from a welding point of view it is the element con-siderably restricting the suitability of a steel or even making welding impossible.

In structural steels the sulphur content is therefore limited to contents lower than 0.06 %, with stainless-steels the contents are even lower than 0.03 %.

However, these low contents must be bound by manganese in order to obtain a usable steel. At hightemperatures, manganese forms with sulphur the compound MnS that in the rolled steel can be madevisible as a wormlike precipitation in the microsection or becomes visible by means of a large magnifica-tion. These precipitations, with stresses in the direction of thickness of the rolling medium, may possiblylead to lamellar tearing.

Figure 3: Phase diagram iron-Sulphur

Figure 4: Phase diagram iron sulfide-iron oxydul


12/47

Structure of the welded joint I IWE-1 / 2.07-1Page 1



1. Weldability of the part

The factors determining the weldability of a part are shown in figure 1.

Figure 1: Weldability of a part

Figure 2 shows the weldability as the resultant of the parameters material, structure and manufacture.

Figure 2: Weldability as resultant of the parameters

The main parameters for weldability are:

a) Suitability for welding: - chemical composition- metallurgical properties- physical properties

b) Welding safety: - structural design- state of stresses

c) Possibility for welding: - preparation for welding

- execution of the welding works- post-treatment


13/47





Expert Guidance:

Dipl.-Ing. Neuhoff


14/47

Theoretical education



Modul 3: Construction and design

Chapter Subject

3.01 Design principles of welded structures

3.02 Fundamentals of the strength of materials

3.03 Joint design


15/47

Design principles of welded structures I IWE-1 / 3.01-1Page 3

Neuhoff 2010 SLV Duisburg Branch of GSI mbH Construction and design


Figure 5: Position of forces and polygon of forces

The calculated determination of the resulting force can easily be done via the components in a rectangu-lar system of co-ordinates.

Example: Graphic determination of the bottom chord and diagonal force of a trussed girder

Figure 6: Graphic determiantion of member forces

Equilibrium of forces

Next to the problem of determining the resulting forces the problem of the equilibrium of forces is equallyimportant.

If two forces are acting, an equilibrium does only exist if the two forces are opposite, of the same amountand situated on a common action line.


16/47

Fundamentals of the strengthof materials Il

IWE-1 / 3.02-2Page 2



Bending moments and axial forces cause similar stresses (axial stresses ) in a component. The result-

ing axial stresses are determined by addition.

1.4 Stresses resulting from shear forces

While the occurring stresses from axial forces and bending moments can be understood easily, the un-derstanding of the stresses arising from shear stressing is difficult.

Shear stressing results in:

a) shear stresses sif two equal forces of opposite direction acting in nearly flat formation stress a

section evenly.

Figure 5: Shear stressing of a pin connection

Portrayed in simplified form an even distribution of stresses in the section can be assumed.

b) shear stresses . during simultaneous bending. The distribution of shear stresses across the sec-

tion can be clarified by a model. If you cut a beam stressed by bending in a horizontal plane, the

equilibrium of the beam element can be represented as follows:

1 2

My,2VzMy,1

Vz

F

x

z1 2

My

Vz

My,1

M

max My

+

+

-

Figure 6: Shear stressing due to simultaneous appearance of shear force and bending moment


17/47

Joint design I IWE-1 / 3.03-1Page 1



1. Preface

The fabrication of welded joints is affected by welding process

constructional requirement material material thickness accessibility affected by working position.

Important attributes for the fabrication of welded joints of high quality are the type of joint, the type ofweld and the joint preparation. In order to avoid misunderstandings it is necessary to define the essentialterms because misconstruction may lead to serious loss of quality. The standard below contains all im-portant terms and gives references for there application.

DEUTSCHE NORM September 2005

DIN EN ISO 17659 DINICS 01.040.25; 25.160.40 Ersatz fr

DIN EN 12345:1999-05

Schweien -Mehrsprachige Benennungen fr Schweiverbindungen mit bildlichenDarstellungen (ISO 17659:2002);Dreisprachige Fassung EN ISO 17659:2004

Welding -Multilingual terms for welded joints with illustrations (ISO 17659:2002);Trilingual version EN ISO 17659:2004

Soudage -Liste multilingue de termes relatifs aux assemblages et aux joints souds, avec illustrations(ISO 17659:2002);Version trilingue EN ISO 17659:2004

2. Definitions

For the purposes of this standard, the following definitions apply:

Jointthe junction of work pieces or the edges of work pieces that are to be joined or have been joined.

Fusion weldingwelding involving localised melting without the application of external force in which the fusion surface(s)has (have) to be melted; filler metal may or may not be added [ISO 857-1].

Welding with pressurewelding in which sufficient external force is applied to cause more or less plastic deformation of both the

contact surfaces, generally without the addition of filler metal; the faying surfaces may be heated to per-mit or facilitate joining [ISO 857-1].


18/47

PART 3



International Welding Engineer (IWE)

Course according to IIW Guideline IAB-252-07

Member of DVS - Deutscher Verband fr Schweien

und verwandte Verfahren e.V. (German Welding Society)


19/47





Expert Guidance:

Dr.-Ing. Winkler

The Document contains standards reproduced by permission of DIN Deutsches Institut fr Normung e.V.The definitive version for the imple-

mentation of this standard is the edition bearing the most recent date of issue, obtainable from Beuth Verlag GmbH, Burggrafenstrasse 6,D-10787 Berlin.


20/47

Theoretical educationPart 3



Modul 1: Welding processes and equipment

Chapter Subject

1.07 TIG welding

1.08 MIG/MAG and flux cored arc welding

1.09 MMA welding

1.10 Submerged-arc welding

1.11 Resistance welding

1.12 Other welding processes

1.13 Cutting and other edge preparation processes

1.14 Surfacing and spraying

1.15 Fully mechanised processes and robotics

1.16 Brazing and soldering

1.17 Joining processes for plastics

1.18 Joining processes for ceramics and composites

1.19 Welding laboratory


21/47

MIG/MAG and flux cored arc welding IIIIWE-3 / 1.08-3

Page 20



The hydrogen pores at aluminium rise. If this process is hindered by the shape of the weld the gas stayin the welding good (Figure 46).

Figure 47 gives an overview of the reasons for pores when MIG/MAG welding.

Figure 34: Pores due to defects at the torch

Figure 35: Pore formation due to wrong torch manipulation /2/


22/47

Resistance welding IIWE-3 / 1.11-1

Page 4

Schreiber 2010 SLV Duisburg Branch of GSI mbH Welding processes and equipment


1.3 Spot Welding Process

A simple spot welding sequence consists of the following parameters:

squeeze time tV [cyc] weld time tS [cyc]

hold time tN [cyc]

welding current IS [kA]

electrode force FE [N]

typical weld sequence for spot welding

1.4 The resistance welding machine

There are different types of welding machines on the market, which will be discussed in a following chap-ter. The elements of all machines are comparable; as an example a stationary type spot welder isshown.

Resistance spot welding machine, air operated (schematic)


23/47

Other welding processes Il and III- Part 1 -

IWE-31.12.1-2 / 1.12.1-3

Page 17

Hesse 2010 SLV Duisburg Branch of GSI mbH Welding processes and equipment


8. Solid-State Laser

At the solid-state laser an active medium consists of a crystal, which is for example of ruby, glass or yt-trium aluminium garnet (YAG). External atoms of chrome or neodymium are deposited in the crystal ofthe YAG-laser. These external atoms are the actual laser-active atoms. The laser active medium is oftenshaped like a stick and situated between the resonator mirrors, Figure 17. Solid-state lasers are acti-vated with optical pumps. This is effected by flash lamps for the pulsed laser and arc lamps for the con-tinuous laser. To optimise the work of the lamps double elliptic reflectors are used.

1

3

4

7 8

2

65

4

1. Active medium2. Output mirror3. High reflective mirror4. Excitation

(Coaxial flashes)5. Pumped light6. Cooling water7. Reflector8. Laser beam

1

3

4

7 8

2

65

4

1. Active medium3. High reflective mirror4. Excitation

(Coaxial flashes)5. Pumped light6. Cooling water7. Reflector8. Laser beam

Figure 17:General assembly of a solid-state radiation source

The solid-state lasers, which are used for welding of materials, are listed in Table 4

Table 4:

Name Material Laser active material Wave length

Rubin-Laser

Nd-Glass-Laser

Nd:YAG-Laser

Rubin

Glass

YAG

Chrome ions (Cr3+)

Neodymium ions (Nd3+)

Neodymium ions (Nd3+)

0,694 m

1,06 m

1,064 m

The industrial standard solid-state lasers have a wave power of 10 W till 5 kW.With the continuous wave laser higher process speeds are approachable than with the pulsed systems(at same power). The pulsed lasers can reach a pulse power up to 20 kW. This causes a higher weldingdepth than with the cw-process. It is possible to weld steels, aluminium, copper and many other metals.


24/47

Surfacing and sprayingIWE-3 / 1.14

Page 21



4.4 Examples of Application

Welded cladding to increase the time of exposure ofsteam generator fire surfaces in garbage-incinerating

plants

Steel cladding of a sand slinger wheel for a streamapparatus

Hauling ventilator in timber industry wear protected withcomposite slap

Wheel loader shovel protected against abrasion andshock

Figure 16: Examples of Application of Surface Coatings by Build-up Welding.


25/47

Joining processes for plastics I and IIIWE-3

1.17-1 / 1.17-2Page 9

Holthaus 2010 SLV Duisburg Branch of GSI mbH Welding processes and equipment


The most frequent causes for mistakes of Heated Tool Spiral Welding are listed as follows:

No visual control at the tubes and other parts No cutting-off of the tube No temperature adjustment of the system components Unsufficient cleaning of the tubes and other parts No or too much mechanical surface treatment No marking the depth Wrong tube support in the ditch line No examination of the ditch line for sharp-edged objects

(stones, fragments and similar objects) Insufficion weathering Wrong welding parameters or wrong magnetic cards

4.1.4 Other Heated tool welding processes

Other heated tool welding processes at rarely used application ranges are shown as follows:

Welding

Weld seam Workpiece

=Workpiece

Thermal element

Heating Warm pushing in

Work piece

Usable area Thermalelemen

t

+

folding and welding

weld

Usable area

Work piece

Hot pushingin

Thermalelement

Work piece

Figure 8: Principle of Heated Tool Groove Welding Figure 9: Principle of welding by bending usinga heated tool

Weld seam

Transportation and

pressure rollersUsable area

Werkstck

Work pieceHeated wedge

Work piece

Elastic thermal

isolation

Work piece

Weld

Separating foil

Usable area

Thermal element

Stamp

Stamp

Separating foil

Usable area

Thermal element

Elastic thermal

isolation

Figure 10: Principle ofheated wedge pressurewelding

Figure 11: Principle ofthermal impulse welding


26/47




Materials and their behaviour duringwelding

Expert Guidance:

Dipl.-Ing. Holthaus



27/47




Module 2: Materials and their behaviour during welding

Chapter Subject

2.08 Plain carbon- and carbon-manganese steels

2.09 Fine-grained steels

2.11 Cracking phenomena in welded joints

2.12 Application of structural and high strength steels

2.13 Low alloyed steels for low temperature applications

2.14 Low alloy creep resistant steels

2.15 Introduction to corrosion

2.16 High-alloyed (stainless) steels

2.17 Introduction to wear

2.18 Protective layers

2.19 High alloy creep resistant and heat resistant steels

2.20 Cast irons and steels

2.21 Copper and copper alloys

2.22 Nickel and nickel alloys


28/47




Chapter Subject

2.23 Aluminium and aluminium alloys

2.24 Other metals and alloys

2.25 Joining dissimilar materials

2.26 Metallographic examinations


29/47

Cracking phenomena in welded joints III IWE-3 / 2.11-3Page 4

Eisenbeis/Bltmann 2010 SLV Duisburg Branch of GSI mbHMaterials and their behaviour

during weldingCopyright by SLV Duisburg. All rights reserved

The effect of hydrogen in the weld metal

An increased hydrogen content (put into the weld metal due to the welding process) or hydrogen loadedtensile specimens lead to embrittlement of the lattice.

The appearance of embrittlement takes place over a short period of time only, within the course of hy-drogen effusion it disappears again.Fish eyes are local separations of material on the microscopic and macroscopic scale showing asbright, round (quasi-) brittle fractured area with a centre (imperfection, inclusion, pore) in a ductile envi-ronment.Fish eyes are formed if hydrogen loaded weld metal is slowly plastically deformed after welding.Micro cracksare favourable generated at lattice imperfections.Areas subject to the risk of microcracks are areas with brittle structural constituents where hydrogen hasgathered in its environment. (E. g. transformation of residual austenite with an increased hydrogen solu-bility in martensite or ferrite + cementite with a relatively high concentration of hydrogen).Delayed cracks (cold cracks)It has been determined that underbead cracks, root cracks, notch cracks and particularly transversecracks can in some cases can be proven only several days after welding.The material separations taking place delayed are influenced by a number of parameters (hydrogensupply, heat treatment, diffusion and effusion paths, structural state, load applied to the weld). Below acertain load the formation of cracks is avoided.The phenomenon of a delayed formation of cracks at high-strength fine-grained structural steels is thereason for various investigations for the determination of the susceptibility to cold cracking and the be-haviour of cold cracks, respectively.

fish eyeSEM image,small magnification

fish-eye yardSEM imagelarge magnification

microcrack in the weld metal surface of a microcrackSEM image,large magnification


30/47

Introduction to corrosion IIWE-3 / 2.15-1

Page 1

Fr. Hempsch 2010 SLV Duisburg Branch of GSI mbH Materials and their behaviourduring welding


If a metal gets into contact with an electrically conductive liquid (electrolyte), the metal atoms are able toenter the liquid as ions. They leave back their outer electrons at the metal surface. These reactionstherefore are controlled also by the electric load of the metal electrode, we call these reactions electro-chemical reactions.

The reverse reaction, the deposition of metal ions out of the liquid on to the metal electrode, is influencedalso by the concentration of the metal ions in the liquid. The current density curves for the anodic metaldissolution and for the cathodic metal deposition can be derived theoretically only. Only the total curvecan be measured practically.

Figure 1: Potential of a metal in an electric conductive liquid

The water molecules from an electric viewpoint are dipoles. Therefore they attach to the electricallyloaded metal electrode. The other ions in the liquid do this in the same way. So an electric double layeron the metal surface is built up. The metal electrode takes its off-load potential ERif it is not influencedfrom outside.

This electric potential of the metal electrode in relation to the electrolyte cannot be measured from out-

side. This is because at a counter electrode dipped into the electrolyte - e. g. a copper wire - similar elec-trochemical reactions would occur and we would measure only the difference.

In this case we only can define the potential of one special electrode to be zero. For this the corrosionscientists have chosen the standard hydrogen electrode, because most of the relevant reactions takeplace in water solutions.

With the hydrogen electrode we make use of the fact, that molecular hydrogen readily dissolves atomi-cally into the platinum without any energy difference.


31/47

High-alloyed (stainless) steelsIllIWE-3 / 2.16-3

Page 5

Metting 2010 SLV Duisburg Branch of GSI mbH Materials and their behaviourduring welding


With colored etching according to Lichtenegger and Blch the structure is good to see.

Figure 6: Crystallization of austenitic weld metal on the base metal

As Figure 6 shows, there is an orientation correlation between the weld metal and the base metal at thefusion line. On the inner part of the weld metal the structure becomes coarser because some crystal ori-entations are overgrown by others.

Figure 7: Hot cracking at the grain boundaries of the weld metal

The hot crack, formed during solidification, is located at the grain boundaries of the weld metal. This canbe seen in the left picture, because the orientation of the cell colonies is visible due to a cellular dendritic

structure. In the lower part of the picture we see a grain boundary which did not crack.


32/47





Expert Guidance:

Dipl.-Ing. Neuhoff



33/47




Module 3: Construction and design

Chapter Subject

3.04 Basics of weld design

3.05 Behaviour of welded structures under different types of loadings

3.06 Design of welded structures with predominantly static loading

3.07 Behaviour of welded structures under dynamic loading

3.08 Design of dynamically loaded welded structures

3.09 Design of welded pressure equipment

3.10 Design of aluminium alloys structures

3.11 Reinforcing-steel welded joints

3.12 Introduction to fracture mechanics


34/47

Basics of weld design I IWE-3 / 3.04-1Page 6



Weld stressing withshear forces Vz

a

SV

y

yz

ll

= [N/mm]

or for intermittent welds

w

w

y

yz

lll

le

a

SV +

= [N/mm]

y = Second order moment of area of the total cross section

related to the y-axis [cm4]

Sy = Static moment (AFz) [cm3]Af = Cross section of the flange [cm]

(continued)

If welds are subject to stresses of the same kind such as axial stresses resulting from axial forces or

bending moments or shear stresses or II resulting from shear or torsional moments, the resultantstresses can be determined by linear superpositioning, taking the sign into account. If welds are subject

to concurrent stresses of different kinds, the reference value w,v of the actual stresses in the welds

have to be determined. The reference value of the actual stresses w,v is the vectorial adding of the indi-

vidual stress components , and II.2

II

22

v,w ++=

When the reference value of the actual stresses is determined only the amount is significant. The direc-tion of the resultant vector is of no importance.

Weld stressing with combined

internal forces

zM

y,w

y

=

;

St,w

zll

A

V= [N/mm]

2

ll

2

v,w += [N/mm]


35/47

Behaviour of welded structuresunder different types of loadings I/II

IWE-33.05-1 / 3.05-2

Page 4



The high axial strains, resulting from the stress concentration of the axial stresses in the so-called notchroot, must lead to proportional transversal contractions as described above. However, these transversalcontractions are hindered by the adjacent material areas. This leads to a 3-axial tensional stress condi-tion. This in turn leads to a change of material behaviour also in the case of tough materials, which can

be called embrittlement due to stress conditions.

Figure 5: Effect of hindered transverse extension

The figure above shows an increase of the strength of material while the deformation capacity is reducedat the same time. This may lead to brittle failure, i. e. a brittle fracture in a component. In addition to the

stress conditions the deformation capacity is influenced by multi-axial stress conditions and can also becaused by the accumulation of welds.

2.3 Brittle failure, brittle fracture

Brittle fracture is a fracture that occurs essentially during stressing of material in the elastic range. Incontrast to ductile fracture brittle fracture involves little or no plastic deformation. External characteristicsof brittle fracture are no gross permanent or plastic deformation of the metal in the region of brittle frac-ture. That is why brittle fracture is described as fracture without deformation. In case of crystalline mate-rials the fracture surface is smooth and has a granular shiny appearance.

Figure 6: Electron microscope photo of a transgranular fracture (cleavage fracture)

Figure 7: Electron microscope photo of an intergranularfracture


36/47

Behaviour of welded structuresunder dynamic loading I-III

IWE-33.07-1 - 3.07-3

Page 24

Ahrens 2010 SLV Duisburg Branch of GSI mbH Construction and design


2.4 Hot spot stress concept

With the hot spot stress concept the stress raisers deriving from the geometry of the components to bewelded are considered.

Additionally the notch effect by the weld including all imperfections and effects by residual stresses andby the material are calculated. The hot spot stresses in welded joints can be measured for instance bystrain gauges or by calculation for instance with method of finite elements. Calculating with hot spotstresses the starting point is the weld transition and the maximum stress is extrapolated. In Figure 25 forthis linear extrapolation suitable values are given as they are taken for hollow sections depending on thewall thickness.

= + +

= + + ges m b k

s

Figure 24: Butt weld with stress distribution at weld transition: Total stress is distributed in membrane-, bending-and notch stress.

Notch stress raiser

Hot spot stress extrapolated

Linear raising hot spot stress

Figure 25: T-joint with stress raiser in the weld area with values for the linear stress extrapolation at the weld

transition.

The hot spot stress is already used in a lot of international and national standards and in the recommen-dations for fatigue calculations of welded structures. It is used in the following references:

IIW recommendations

Eurocode 3

FKM guideline

Germanischer Lloyd

AD rules (pressure vessels)

draft for Eurocode 9

The values for the hot spot stress concept are used for welded joints of steel and aluminium.


37/47

Design of welded pressureequipment Il

IWE-3 / 3.09-2Page 5

Kimmeskamp 2010 SLV Duisburg Branch of GSI mbH Construction and design


Circumferential stress u Equilibrium of forces by means of comparing theareas:

sL2A

dLA

:with

A

pA

ApA

u

ipu

u

pu

u

uupu

=

=

=

=

s2

pdiu

=

vessel formula(without allowances)

Longitudinal stress l

with:

sdA

4

dA

A

pA

ApA

il

2

ipl

l

pl

l

llpl

=

=

=

=

s4

pdil

=

The circumferential stress is two times higher than the longitudinal stress. Therefore, the longitudinalweld is two times more subjected to stress than the circumferential weld.


38/47




Fabrication, applications engineering

Expert Guidance:

Dipl.-Ing. Mhrlein



39/47




Module 4: Fabrication, applications engineering

Chapter Subject

4.01 Introduction to quality assurance in welded fabrication

4.02 Quality control during manufacture

4.03 Residualstresses and distortion

4.04 Plant facilities, welding jigs and fixtures

4.05 Health and safety

4.06 Measurement, control and recording in welding

4.07-1 Non-destructive testing I- Magnetic particle flaw detection -

4.07-2 Non-destructive testing II- Magnetic particle flaw detection -

4.07-3 Non-destructive testing III- Penetrant testing (PT) -

4.07-4 Non-destructive testing IV- Penetrant testing (PT) -

4.07-5 Non-destructive testing V- Ultrasonic testing -

4.07-6 Non-destructive testing VI

4.07-7 Non-destructive testing VII- Radiographic testing -

4.07-8 Non-destructive testing VIII- ISO 5817 -

4.07-9 Practical exercise


40/47




Chapter Subject

4.07-10 Practical exercise

4.08 Economics

4.09 Repair welding

4.10 Fitness for purpose

4.11-1 4.11-20 Case studies


41/47

Introduction to quality assurance inwelded fabrication IlI

IWE-3 / 4.01-3Page 8

2010 SLV Duisburg Branch of GSI mbH Fabrication, applications engineering


CENs deliverables are:

EN the traditional European Standard, leading to full Europe-wide implementation; also servingEuropean regulatory needs of the new approach

ENV European Pre-standard, serving as an experimental specification where the state-of the art-isnot stable or full implementation not yet possible.

CR CEN Report for information and transfer of knowledge.

CEN/TC 121 (Secretariat Denmark) is involved with welding and allied processes.

CEN/TC 121 aims for a structure of the European standards for welding, which permits application stan-dards for welded products and structures to formulate virtually all requirements related to welding fabri-cation simply by referring to one or more EN standards for welding. This is technically feasible becausesuch requirements depend on welding technology and the nature of the base materials, but very little ornot at all on the nature of the welded product or structure.

Application

standard

Contract

Legal

requiremnts

Standards

for

welding

Figure 9: Reference from application standard

Even though the system of standards for welding is structured so as to permit reference by application

standards, all standards for welding may also be used directly as a reference in contracts, on a standalone basis, as illustrated below in Figure 10. The standards may also be used by manufacturers, on anentirely voluntary basis, for in-house purposes. References will then typically be included in the manufac-turers quality manual and other specifications. Principles are shown in Figure 11 below.

Contract

Legal

requirements

Standards

for

welding

Manufacturer's

requirements

Standards

for

welding

Figure 10: Reference from contract Figure 11: Reference from manufacturers quality manualand other specifications


42/47

Residual stresses and distortion IlIWE-3 / 4.03-2

Page 15

Mhrlein 2010 SLV Duisburg Branch of GSI mbH Fabrication, applications engineering


welding of the bottom flange

welding of the top flange

orwelding the bottom and top flange simultaneously and than going on

welding of the web platewelding of the fillet welds at the bottom flangewelding of the fillet welds at the top flange

C. Welding sequence of the flanges to avoid angular distortionThe preparation of the joint should carried out as an unsymmetrical double V weld.

Welding sequence

1. Start welding at the large V opening

2. Remove root layer by grinding or gouging. If gouging,grind the surface before starting with a surface crack test.

3. Welding the complete root side

4. Welding the rest part of the large V-opening

5. Start non-destructive tests of the weld like e.g.- ultrasonic test and / or- radiographic test


43/47

Measurement, controlling andrecording in welding I and II

IWE-34.06-1 / 4.06-2

Page 13

Bockting 2010 SLV Duisburg Branch of GSI mbH Fabrication, applications engineering


4.3 Wire feed speed at MSG and the automatic TIG process

There are three ways to measure wire speed.

The first way is to transport the wire by a motor. This motor is always a DC motor. The value of the DCvoltage on the connector of the wire drive motor determines the value of the rotation speed. If the valueof the motor voltage is high, then the rotation speed is also high. When we measure the motor voltagewith a volt meter, we have the value of the wire speed. But there is one problem. When we have a slip-page between the wire roll and the wire, we have an incorrect value on the display.

The second way to measure wire speed is a directmethod.

(A)

You can put the sensor over the wire, and the rotationspeed.

(B)

The third and final way is that inside the sensor case is apulse generator. On the other side we have a pulsecounter. It directly displays the wire speed in m/min.One option is for the counter to calculate how much wirewe have used over a working day. Another option is tofind the sum of the weight of the wire. Also, we can calcu-late the sum of the welding time.

(C)

This sensor is one part of a QS-System.The metering range is 0...30 m/min.Accuracy is 2.5 % of the full scale.

(D)


44/47

Repair welding IWE-3 / 4.09Page 4

2010 SLV Duisburg Branch of GSI mbH Fabrication, applications engineering


5.2 Buffering

Buffering may be done to join materials with different need of heat treatment or different heat treatmenttemperatures.

buffering weld metal

high strength steelor heat resistance steel

low or unalloyedstructural steel

Figure 2 Structural steel

5.3 Hard facing

Building up a special surface with materials of different mechanical properties (e.g. high hardness val-ues) for wear resistance.

ductile parent metal

hard facing withhigh hardness value

Figure 3

6. Example

Repair welding of a damaged toothed rack.

Figure 4


45/47

I m p o r t a n t please read carefully before installing

In case you bought your SLV product in Germany, Switzerland, Austria of in Liechtenstein thefollowing licence contract is valid.

Schweitechnische Lehr- und Versuchsanstalt Duisburg

(In the following text also called SLV Duisburg)

Software Licence Contract

Following are the contract conditions for using the SLV-software by you, the final consumer (alsocalled licensee).

Therefore, read the following text completely and carefully.

If you do not agree on the contract conditions you are not allowed to continue using the program.

Contract Conditions

1. Subject to the contract

Subject to the contract is the computer program on the CD-ROM, the program description and theoperating instruction as well as other written material. Later on it will also be defined as software.

SLV Duisburg informs that according to the technical standing it is not possible to program computersoftware without any mistakes in all kinds of use and combination.

Therefore, only software is subject to the contract which is basically to use in the sense of the programdescription and the operating instruction.

2. Extend of use

For the duration of this contract SLV Duisburg grants you the simple, not excludable and personal right(later on defined as license) to only use the included copy of the SLV software on one computer atone place.As licensee you are enabled to transfer the software, saved on a CD-ROM, from one to anothercomputer under the condition that it is any time only played on one single computer.

A further use is not allowed.

3. Special restriction

The licensee is not allowed to,

a) Transfer or, in any form, give the software including all pictures, animations, videos etc. or thecorresponding written material to a third person, without a previous agreement in writing from SLVDuisburg.b) Transfer the software via a net or a data transfer channel from one computer to another.c) Change, translate, redevelop, decompilate or to disassembly the software without any previousagreement in writing from SLV Duisburg.d) Develop writings on the basis of the software or copy the written material.e) Translate, change or develop writings on the basis of the written material.

4. Rights

By purchasing the product you only receive the property of the corporal CD-ROM on which thesoftware is programmed. A reception of rights of the software itself is not connected to the purchase.

SLV-Duisburg especially keeps the rights of launching, copying and using the software.

5. Copying


46/47

The software and the included written material are copywritten.

The program is via a code clearly registered on your name.

If the software does not have a copy protection you have the right to make one copy as reserve butonly for security purposes. On the copy you must indicate the copy write annotation of SLV Duisburg.

A, in the software indicated, copywrite record as well as your registered number must not be deleted.

It is explicitly forbidden to totally or partly copy the written material in the original or amended versionmixed or included with/in other software or to copy it in a different form.

6. Transfer and rights to use

The right of using the software can only be transferred to a third person with the previous agreementof SLV Duisburg and only under condition of this contract.

Giving as a present, renting and loaning of this software is explicitly forbidden.

7. Contract duration

The contract is valid for a certain time. It is independent on the duration of the correspondence course.

If one condition of the contract is not fulfilled the licensees right to make use of the software will betaken away without cancelling the contract. In this case the licensee if obliged to destroy the originalCD-ROM including all copies made of the software as well as amended versions and the writtenmaterial.

8. Indemnification by breach of contract

The SLV Duisburg informs that you are responsible for all damages based on breach of copywritewhich occur for SLV Duisburg as a result of a breach of contract.

9. Changes and updates

SLV Duisburg is not allowed to update the software at will.

10. guarantee and responsibility of SLV Duisburg

a) SLV Duisburg guarantees the original licensee that the time of transfer of the CD ROM on which thesoftware is copied and the hardware included with the software are under normal working conditionsand at normal maintenance of material without any mistakes.b) In the case that the CD-ROM or the included hardware is faulty the purchaser can demand asubstitute delivery in-between the following six months. He has to give back the CD-ROM including thehardware as well as the reserve copy and the written material and a copy of the bill/receipt to the SLVDuisburg or the shop where he purchased the product.

c) If a mistake is not corrected by a substitute delivery in-between the period mentioned in 10 b, thepurchaser can demand reductions of the purchase price or cancel the contract.d) In accordance to the reasons mentioned in 1. SLV Duisburg does not accept any responsibility forthe freedom of errors of the software. SLV Duisburg does especially not accept any responsibility thatthe software meets the request and purpose of the purchaser or that it works in combination with otherprograms chosen by the user. The responsibility for the right choice and the consequences of usingthe software as well as the expected and achieved results are at the purchaser.The same is also valid for the written material which accompanies the software. Is the software not touse in the sense of 1. the purchaser has the right to cancel the contract. SLV Duisburg has the sameright if the production of usable software with appropriate effort is not in the sense of 1.e) SLV Duisburg is not responsible for any damage; only if the damage has been caused on purposeor culpable negligence on the part of SLV Duisburg. For traders the responsibility for culpablenegligence is excluded.

Responsibility due to a possibly assured characteristics by SLV Duisburg remains untouched.

11. In the case the licensee is trader it will made use of the German law for the contract.


47/47

12. For all rights and obligations resulting from the contract, Duisburg is place of performance andjuristiction for both parties.

If you have any question about your SLV license contract or you would like to contact SLV Duisburg,please write to:

Schweitechnische Lehr- und Versuchsanstalt Duisburg, Niederlassung der GSI mbHBismarkstrae 85Postfach 101 262D-47012 Duisburg,

Phone: interior : 02 03/3 78 10 , exterior: 00 4 92 03/3 78 10,Fax: interior: 02 03/3 78 12 28, exterior: 00 4 92 03/ 3 78 12 28

demoversion iwe 2011

Documents