sysweld welding report

5/23/2018 Sysweld Welding Report

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MEM661 : APPLIED WELDING ENGINEERING

SYSWELD Assignment

STUDENT NAME : MUHAMMAD AATIQ BIN AZALI 2010742349

MOHD FATHAN BIN MOHD IBRAHIM 2010547301

SITI NUR FASEHAH BINTI ROSLAN 2010333339

MOHD ILYAS HAKIM BIN IBRAHIM 2010967927

LECTURER NAME : SUNHAJI KIYAI ABAS (ASSOC. PROF)


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1.0 INTRODUCTION

Simulation is the best approach to master design, manufacturing process and in service problems

at the earliest product stage possible. SYSWELD is the leading tool for the simulation of heat treatment,

welding and welding assembly processes, taking into account all aspects of material behaviour, designand process. SYSWELD is a powerful tool that guides engineers to find out the optimum process

parameters with respect to distortions, residual stresses and plastic strains.

Graph 1: The intersection point between distortions and plastic strains lines show the optimum point of

welding.

SYSWELD is a finite element (FEM) software that simulates all usual heat treatment

processes like bulk hardening, surface hardening, tempering and hardening and tempering, as

well as thermo-chemical treatment like case hardening, carbonitriding, nitriding and

nitrocarburising. The software computes distortions of parts, residual stresses, plastic strains and

yield strength depending on the mixture of phases of the material in use, during and at the end of

the heat treatment process, plus the hardness at the end of the process. Main results obtained after

a heat treatment simulation includes temperature field and thermal flux, phase proportions,

hardness, distortions, stresses, plastic strains, yield stress and others.

The Heat Source Fitting tool (HSF) is a facility available within SYSWELD, which

enables the user to calibrate the parameters of a heat source and then use this heat source to

perform a steady state thermal analysis of the welding process. This steady-state analysis takes a


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relatively short amount of time to run. Therefore, the user is able to calibrate the heat source by

adjusting these parameters in an iterativemanner.

Technical Background

The technical background of heat treatment is quite complex. It involves heat transfer, phase

transformations and mechanics including phase transformation.

Figure 1: Physical effects and their interaction in thermochemical-metallurgical simulation

of case hardening.

Figure 2: Interrelated physical phenomena


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Simulation Engineering

With the help of the Heat Treatment Advisor, the set-up of a numerical computation is extremely

fast. This does not mean that the simulation engineering is simple. The physics behind a heat

treatment simulation is quite complex, and a user-friendly intuitively driven graphical user

interface will not change that. In order to avoid obtaining incorrect results from an incorrect

model and bearing in mind a remark from Albert Einstein, One should never do too much but

never less than necessary, SYSWELD provides a very detailed training course for the

simulation of heat treatment that covers all real life situations. An extended user guide for best

simulation engineering practice gives the best way to transfer practical problems into a 1 heat

treatment simulation and the advisor primer shows mouse-click by mouse-click how to use the

software. Using SYSWELD, heat treatment simulation engineering is now a straightforward and

efficient task.

Software and Applications Presentation

SYSWELD for heat treatment provides dedicated solutions for heat treatment practitioners as

well as for part designers. Heat treatment practitioners will focus on the feasibility of the heat

treatment process and need answers to their questions instantly. Consequently, a dedicated

packaged solution is available for them, fitting well to the needs of a heat treatment job shop.

Part designers focus on the design of parts and try to find the optimum between cost, part shape,

material, and heat treatment process. Consequently, a dedicated package is available for the

design engineer, providing unmatched meshing and computation capabilities, both on PC and

UNIX based computers.

Fitting the Continuous Cooling Diagram

If specific information is not yet available in the SYSWELD database, it is necessary to adjust

the continuous cooling transformation diagram of the steel, extracting basic parameters from an

ITT diagram and parameters for the fine-tuning from the CCT-diagram. For numerical reasons, it

is preferable to describe the cooling behavior of steel by differential equations rather then by

pairs of temperature-proportion values.

Those differential equations have been defined, for example by Johnson-Mehl-Avrami and

Leblond. They contain phenomenological parameters that have to be adjusted individually for

each CCT diagram. Using the PHASE module and the ITT / CCT display tool, the adjustment of


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a CCT-diagram is a straightforward and simple task. It is important to notice that the adjustment

has to be done only once for each steel. The results can be stored in a database and are then

accessible for further computations via a mouse-click. The major steels used in heat treatment

are already available in the SYSWELD database.

Figure 4: CCT-diagram of a 100Cr6 steelsource

Database for Thermal and Mechanical Material Properties

The thermal, metallurgical and mechanical material properties of a heat-treated steel are quite

complex and depend on temperature, phases and carbon content. SYSWELD features a

comprehensive material database including the major steels that are used for case hardening,

surface hardening and through hardening. It is important to notice that the values given in the

SYSWELD material database are average values extracted from experiments and literature;

missing values have been completed by best simulation engineering practice. It is important to

note that properties of steel depend on the manufacturer, the year, the country etc. The material

properties in the SYSWELD material database therefore represent an average material that will

give good tendencies. In no case, the data will fit precisely to individual steel.


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The Heat Treatment Advisor

The Heat Treatment Advisor is a graphical user interface that allows an intuitive and process-

driven methodology to set-up simulations. Once a dedicated project is defined and stored, parts,

process, and material parameters can be exchanged with a few mouse-clicks within the project

and in less than 1 minute a computation of a variant can be started. With the help of the advisor,

case hardening and through hardening processes can be fully defined. In case of surface

hardening, a few more simple operations with the standard capabilities of the software are

needed to adjust the energy input through the surface. Delivered with the software is an

illustrated advisor primer that shows, systematically, how to perform an industrial heat treatment

study. Set-up of computations with the Advisor is therefore efficient.

Figure 5: Intuitive and

straightforward set up of a heat

treatment simulation with the Heat

Treatment Wizard

Automatic Solver

The SYSWELD solver provides an automatic solution for heat treatment problems, covering all

related complex mathematics and material physics. Depending on temperature, phase

proportions, and proportion of chemical elements, thermal and mechanical properties are

computed, including large strains. Isotropic and kinematic hardening (including phase

transformations), transformation plasticity, nonlinear mixture rules for the yield stress of phases,

phase dependent strain hardening, restoring of strain hardening during diffusion controlled phase

transformations, melting and solidification of material, material properties depending on

temperature, phases and proportion of chemical elements and all features dedicated to the

methodology of finite elements are taken into account. The solver is unique and a result of about

50 men-years of development work. It is important to notice that the user does not need to be


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familiar with the mathematics involved in this solver in order to perform heat treatment

computations. The only work needed to perform a computation is to load the project and to start

the solver.

Figure 6: Launching a computation the only work necessary is to load the project name

Multi-Physics Post-Processor

The multi-physics post-processing capabilities provide instantaneous process information for the

evolution of [6]

Temperature field

Heating and cooling rates

Metallurgical structure of the material

Distortions

Stresses

Yield stress of the modified material

Plastic strains

SYSWELD provides a variety of techniques for reviewing process results including

Contour plots

Iso-lines and iso-surfaces

Vector-Display

X-Y diagrams

Symbol plots

Numerical presentation

Cutting planes

Animations


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The Jominy TestIn SYSWELD, the jominy test is implemented as predefined ready-to-run simulation project.

The user has to define only the chemical composition of the steel, the computation of the jominy

test is done fully automatically. At the end of the computation, the most important results like for

example the hardness profile are displayed. The jominy test is the key to a precise heat treatment

simulation: Once the computed hardness coincides well with the measured hardness, it is secured

that the CCT-diagram of the steel under examination is numerically well implemented for the

full bandwidth of possible cooling rates. In case of discrepancies, the CCT diagram can be

modified in order to meet precisely the measured hardness profile.

Due to the fact that the formulas used for the hardness computation are empirically approved,

existing CCT diagrams can be tuned following recent hardness measurements. Based on the

optimized CCT-diagram, the core hardness of complex parts can be precisely predicted, which is

of utmost importance for the lifetime of parts and components under dynamic loads.

Figure 7: Computed

hardness of a through

hardened train wheel

Figure 8: Distortions after

quenching

Figure 9: Distortion of a

large gear after quenching


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Figure 10: Comparison of computed and measured hardness of a jominy test of 16MnC


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2.0 LITERATURES REVIEW

Welding Distortion

Welding distortion can be defined as the non-uniform expansion and contraction of weld metal

and adjacent base metal during the heating and cooling cycle of the welding process. Distortion

is a consideration when arc welding all materials, and the principles behind this reaction are

fundamentally the same. However, when welding aluminum, compared to carbon steels, the

effects of some of the main contributing factors for distortion are increased. Aluminum has high

thermal conductivity, a property that substantially affects weldability. The thermal conductivity

of aluminum is about five times that of low-carbon steel. Aluminum also has high solidification

shrinkage, around 6% by volume, and also a high coefficient of thermal expansion. When arc

welding aluminum, high localized heating to the material in and around the weld area is applied.

There is a direct relationship between the amount of temperature change and the change in

dimension of a material when heated. This change is based on the coefficient of expansion the

measure of the linear increase per unit length based on the change in temperature of the material.

Aluminum has one of the highest coefficient of expansion ratios, and it changes its dimension

almost twice as much as steel for the same temperature change. Type of welding distortion such

as:-


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Cause Of Distortion

Because welding involves highly localised heating of joint edges to fuse the material, non-

uniform stresses are set up in the component because of expansion and contraction of the heated

material. Initially, compressive stresses are created in the surrounding cold parent metal whenthe weld pool is formed due to the thermal expansion of the hot metal (heat affected zone)

adjacent to the weld pool. However, tensile stresses occur on cooling when the contraction of the

weld metal and the immediate heat affected zone is resisted by the bulk of the cold parent metal.

The magnitude of thermal stresses induced into the material can be seen by the volume change in

the weld area on solidification and subsequent cooling to room temperature. For example, when

welding steel, the molten weld metal volume will be reduced by approximately 3% on

solidification and the volume of the solidified weld metal/heat affected zone (HAZ) will be

reduced by a further 7% as its temperature falls from the melting point of steel to room

temperature.

If the stresses generated from thermal expansion/contraction exceed the yield strength of the

parent metal, localised plastic deformation of the metal occurs. Plastic deformation causes a

permanent reduction in the component dimensions and distorts the structure. [2]

Limited Way To Reduce The Distortion

The effects of weld shrinkage can never be entirely eliminated but you can keep them to a

minimum by taking a few practical steps as follows:

Reducing the metal weld volume to avoid overfill and consider the use of intermittentwelding

Minimizing the number of weld runs and positioning and balancing the welds correctlyround the axis

Using backstep or skip welding techniques, which involves laying short welds in theopposite direction

Making allowance for shrinkage by pre-setting the parts to be welded out of position Planning the welding sequence to ensure that shrinkages are counteracted progressively


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When cutting, it is possible to limit distortion by supporting the plate so it can expand

freely without buckling; ensuring the plate is flat; allowing sufficient weld material when cutting

in from corners and using a jig-saw pattern to lock the cut pieces together when multiple cutting.

Distortion can be avoided or significantly reduced when welding structural steelwork by using

fixing devices, such as strongbacks or wedges to pre-set seams in plates; flexible clamps to

bring parts to the required gap before welding or clamps for thin sheet welding. Longitudinal

stiffeners can also be used to limit this type of bowing. It is also important to use the correct

welding sequence, such as welding the frame before a cover plate. Pre-bending or pre-setting

techniques may also help to prevent distortion and water can be used to cool the process. Pipes

and tubes can suffer distortion after welding and this can be prevented by using strongbacks

attached with straps and wedges inside or outside the longitudinal joint; using backing strips to

overcome transverse shrinkage or pre-setting or using back to back pairs when welding flanges

to pipes. In summary, if welding distortion is likely to be a problem, it can be avoided or

minimised by advance planning and following best practice. [3]

Also for the same problem that is, a way to reduce the distortion effect, using the

preheating base metal by raising the temperature of the entire part before welding reduces

temperature difference, residual stress and distortion. Second solution is peening means

hammering the weld metal usually with an air hammer, slightly reshapes the metal and

redistributes concentrated forces. In a multi-pass weld this is done between each pass. This

method can be helpful but depend on the skill and judgment of the weldor, peening consistency

is difficult to control. Next is stress relieving heat treatment by using an oven or electric heating

coil, the entire part or the weldment area is heated high enough to remove weld induced stress.

This commonly done in structural steel work. Lastly are brazing or soldering instead of welding.

Since brazing and soldering expose the work piece to much lower temperature than weling, these

two process can be used when the strength of welding s not required. [5]


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Way To Reduce The Effect Of Distortion From Welding

First, preset the part. Then tacking welds the part slightly out of position and let residual force

bring them into proper position. Such as showing hot a t- joint are handled.

Use equal distortion force to balance each other by using two ( or more ) weld beads this could

be done by putting a filler weld on the both side of the t-joint. Initial joint design (left) and

balance force designs (right)

Use chain intermittent or staggered intermittent weld beads. Intermittent beads not only balance

one another, but also by reducing the total amount of the weld bead, reduce total residual force.

Even a single intermitted weld bead will have less distortion than a single continuous weld bead

and often the strength of a continuous bead is not needed. Using chain intermittent (left) or

staggered intermittent weld (right) to balance a force and reduce total weld bead metal.


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Use a v-groove and filler weld in place of a fillet weld alone to balance residual stress[5]

Factors Affecting Distortion

If a metal is uniformly heated and cooled there would be almost no distortion. However,

because the material is locally heated and restrained by the surrounding cold metal, stresses are

generated higher than the material yield stress causing permanent distortion. The principal

factors affecting the type and degree of distortion are:

1. Parent material propertiesParent material properties which influence distortion are coefficient of thermal expansion and

specific heat per unit volume. As distortion is determined by expansion and contraction of the

material, the coefficient of thermal expansion of the material plays a significant role in

determining the stresses generated during welding and, hence, the degree of distortion. For

example, as stainless steel has a higher coefficient of expansion than plain carbon steel, it is more

likely to suffer from distortion.


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2. RestraintIf a component is welded without any external restraint, it distorts to relieve the welding stresses.

So, methods of restraint, such as 'strong-backs' in butt welds, can prevent movement and reduce

distortion. As restraint produces higher levels of residual stress in the material, there is a greaterrisk of cracking in weld metal and HAZ especially in crack-sensitive materials.

3. Joint designBoth butt and fillet joints are prone to distortion. It can be minimised in butt joints by adopting a

joint type which balances the thermal stresses through the plate thickness. For example, a

double-sided in preference to a single-sided weld. Double-sided fillet welds should eliminate

angular distortion of the upstanding member, especially if the two welds are deposited at the

same time.

4. Part fit-upFit-up should be uniform to produce predictable and consistent shrinkage. Excessive joint gap

can also increase the degree of distortion by increasing the amount of weld metal needed to fill

the joint. The joints should be adequately tacked to prevent relative movement between the parts

during welding.

5. Welding procedureThis influences the degree of distortion mainly through its effect on the heat input. As welding

procedure is usually selected for reasons of quality and productivity, the welder has limited

scope for reducing distortion. As a general rule, weld volume should be kept to a minimum.

Also, the welding sequence and technique should aim to balance the thermally induced stresses

around the neutral axis of the component.[4]


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What Residual Stress Occur In A T-Joint And What Deformation Produce.

Figure showing both longitudinal and transverse stresses in the weld bead. There is a second

weld bead on the back side of the t-joint. Because the longitudinal stress on each side of the joint

balance each other the vertical member of the t-joint remains straight. Such as longitudinal an

transverse stress in the t-joint (left) and the distortion the cause (right) [5].


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5.0 DATA AND RESULT

GMAW Fillet Specific Data Test


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Simulation From Welding Simulation Software (SYSWELD)

Figure: Result from SYSWELD software

Figure : Distortions effect


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Figure : Weld Bead from SYSWELD software


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DISCUSSION

A welding defect is any flaw that compromises the usefulness of aweldment.There is a

great variety of welding defects. Welding imperfections are classified according to ISO

6520 while their acceptable limits are specified in ISO 5817 and ISO 10042.

Distortion or deformation can occur during welding as a result of the non-uniform

expansion and contraction of the weld and base metal during the heating and cooling cycle.

Stresses form in the weld as a result of the changes in volume, particularly if the weld is

restrained by the fixed components or other materials surrounding it. If the restraints are partly

removed, these stresses can cause the base material to distort and may even result in tears or

fractures. Of course, distortion can be very costly to correct, so prevention is important.

Welding methods that involve the melting of metal at the site of the joint necessarily are

prone to shrinkage as the heated metal cools. Shrinkage then introduces residual stresses and

distortion. Distortion can pose a major problem, since the final product is not the desired shape.

To alleviate certain types of distortion the workpieces can be offset so that after welding the

product is the correct shape. The following pictures describe various types of welding distortion.

Transverse shrinkage Angular distortion Longitudinal shrinkage

Fillet distortion Neutral axis distortion
http://en.wiktionary.org/wiki/weldmenthttp://en.wikipedia.org/wiki/File:Welding_neutral_axis_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_fillet_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_longitudinal.svghttp://en.wikipedia.org/wiki/File:Welding_angular_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_transverse.svghttp://en.wikipedia.org/wiki/File:Welding_neutral_axis_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_fillet_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_longitudinal.svghttp://en.wikipedia.org/wiki/File:Welding_angular_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_transverse.svghttp://en.wikipedia.org/wiki/File:Welding_neutral_axis_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_fillet_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_longitudinal.svghttp://en.wikipedia.org/wiki/File:Welding_angular_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_transverse.svghttp://en.wikipedia.org/wiki/File:Welding_neutral_axis_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_fillet_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_longitudinal.svghttp://en.wikipedia.org/wiki/File:Welding_angular_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_transverse.svghttp://en.wikipedia.org/wiki/File:Welding_neutral_axis_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_fillet_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_longitudinal.svghttp://en.wikipedia.org/wiki/File:Welding_angular_distortion.svghttp://en.wikipedia.org/wiki/File:Welding_shrinkage_transverse.svghttp://en.wiktionary.org/wiki/weldment


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There are many factors that can cause welding or cutting distortion and it is very difficult

to predict the exact amount of distortion that is likely to occur. Some of the factors that should be

considered include the degree of restraint; the thermal and other properties of the parent material;

inherent stresses induced from previous metal-working processes such as rolling, forming and

bending; design of weldment; accuracy of manufacture and the nature of the welding process

itselfthe type of process, symmetry of the joint, preheat and the number and sequence of welds

required.

Based on the SYSWELD simulation, the weld bead of GMAW is overall good. The heat

affected zone, weld metal and base metal is passed based on AWS. There were some distortions

effect from welding process. The figure below show that the comparison between before and

after welding process. For the test distortion, we use Coordinate Measuring Machine to calculate

distortion happen in specimen after welding process.

So, we use three points to test the specimen distortion. For the point 1 before welding

process is 78.040 millimeters and after welding process, the steel becomes distorted to 74.107

millimeter. For the 2 and 3 points before weld is 77.940 and 77.777 millimeters, after weld

process the value distort to 73.766 millimeter and 73.618 millimeter.

Figure : Before Welding Process

Figure : After Welding Process


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The effects of weld shrinkage can never be entirely eliminated but can keep them to a minimum

by taking a few practical steps as follows:

i. Reducing the metal weld volume to avoid overfill and consider the use of intermittentwelding

ii. Minimizing the number of weld runsiii. Positioning and balancing the welds correctly rounds the axisiv. Using backstep or skip welding techniques, which involves laying short welds in the

opposite direction

v. Making allowance for shrinkage by pre-setting the parts to be welded out of positionvi. Planning the welding sequence to ensure that shrinkages are counteracted progressively

vii. Shortening the welding time

When cutting, it is possible to limit distortion by supporting the plate so it can expand freely

without buckling; ensuring the plate is flat; allowing sufficient weld material when cutting in

from corners and using a jig-saw pattern to lock the cut pieces together when multiple cutting.

Distortion can be avoided or significantly reduced when welding structural steelwork by using

fixing devices, such as strongbacks or wedges to pre-set seams in plates; flexible clamps to bring

parts to the required gap before welding or clamps for thin sheet welding. Longitudinal stiffeners

can also be used to limit this type of bowing. It is also important to use the correct welding

sequence, such as welding the frame before a cover plate. Pre-bending or pre-setting techniques

may also help to prevent distortion and water can be used to cool the process.

CONCLUSION

In summary, if welding distortion is likely to be a problem, it can be avoided or

minimized by advance planning and following best practice. So, from this project, we can

conclude the project finished successfully after taking some measurement all the specifications in

SYSWELD simulation and Distortion Test.


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REFERENCE

1. Thermal Distortion In Aluminum Welded Structures Strategies Minimize Non-uniformDimensional Changes Caused By Heat StressTony Anderson

2. Computational Materials Science A Study On The Influence Of Clamping On WeldingDistortion45 (2009) 9991005 T. Schenk, I.M. Richardson, M. Kraska, S. Ohnimus

3. www.airproducts.co.uk/safewelding4. http://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-

033/

5. Controlling Distortion by H.G Bohn
http://www.aws.org/wj/feb03/feature1.html#Ahttp://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-033/http://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-033/http://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-033/http://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-033/http://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-033/http://www.twi.co.uk/technical-knowledge/job-knowledge/distortion-types-and-causes-033/http://www.aws.org/wj/feb03/feature1.html#A

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