AWS B4.0: 2007 Standard Methods for Mechanical Testing of Welds

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CLAUSE 10. WELDABILITY TESTING AWS B4.0:2007

Figure 10.2.4—Sectioning for the Longitudinal Notch

Note: L/2 = Half fillet weld leg length.

Figure 10.2.5—Sectioning for the Transverse Notch

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AWS B4.0:2007 CLAUSE 10. WELDABILITY TESTING

Figure 10.2.6—Location of Metallographic Specimens for

Examination of Cracks in the Slotted Cruciform Test

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CLAUSE 10. WELDABILITY TESTING AWS B4.0:2007

CRUCIFORM TEST RESULTS

Company Name _____________________________________________________________ Date _______________________

Job/Test No. ________________________________________________________________ Sheet _________ of __________

Description of Investigation ____________________________________________________________________________________

Base Metal Identification _______________________________ Thickness ___________________________________________

Base Metal Heat Treatment_____________________________ Heat No. ____________________________________________

Composition:

C__________ Si __________ Mn ________ P __________ S__________ Cr__________ Mo ________

Ni _________ V __________ Cu_________ Nb _________ Ca_________ B __________ Ti _________

Al _________ N __________ _________ __________ _________ __________ _________

Welding Procedure Spec. No. ___________________________ Welding Process ______________________________________

Electrode/Wire Spec. No. ______________________________ Commercial Name ____________________________________

Diameter ___________________________________________ Baking Treatment _____________________________________

Shielding Gas _______________________________________ Flow Rate ___________________________________________

Shielding Flux _______________________________________ Flux Size ____________________________________________

Current ____________________________________________ Preheat Temp.________________________________________

Voltage ____________________________________________ Interpass Temp._______________________________________

Polarity ____________________________________________ Postweld Heat Treatment _______________________________

Travel Speed ________________________________________ Aging Time __________________________________________

Heat Input __________________________________________ Ambient Temp. _______________________________________

Test Weld Size_______________________________________ Ambient Humidity _____________________________________

Number of Weld Beads ________________________________

Hydrogen Determination Method ________________________________________________ Date _______________________

__________________________________________________ Result ______________________________________________

Weld Pass Identification:

Results:

Remarks __________________________________________________________________________________________________

Tested By __________________________________________________________________

Signature___________________________________________________________________ Date _______________________

Figure 10.2.7—Suggested Data Sheet for Cruciform Test

Weld/Section

No.

Result

(C or NC)

Crack Location

and Length

Weld/Section

No.

Result

(C or NC)

Crack Location

and Length

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AWS B4.0:2007 CLAUSE 10. WELDABILITY TESTING

10.3 Implant Test

10.3.1 Scope

10.3.1.1 The implant test is used to evaluate the sus-

ceptibility of low-alloy steels to hydrogen-assisted crack-

ing. The test may be used to evaluate the effects on HAZ

cracking susceptibility of welding consumables, welding

heat input, preheating, postheating, or a combination of

these parameters.

10.3.1.2 This standard is applicable to the following:

(1) Qualification of materials and welding proce-

dures where specific acceptance standards have been

specified;

(2) Information, basis of acceptance, or manufacturing

and quality control; and

(3) Research and development.

10.3.1.3 This test is applicable only to HAZ cracking

caused by hydrogen.

10.3.1.4 The following information shall be furnished:

(1) Base metal identification and specification;

(2) Implant metal identification and specification;

(3) Filler metal identification, specification, and

classification;

(4) Specific type and number of specimens required;

(5) Anticipated strength property values;

(6) Weld procedure (process and parameters); and

(7) Report form when required.

10.3.2 Normative References. The following standards

contain provisions which, through reference in this text,

constitute mandatory provisions of this test. For undated

references, the latest edition of the referenced standard

shall apply. For dated references, subsequent amend-

ments to, or revisions of, any of these publications do not

apply.

ASME Documents:

ASME B46.1, Surface Texture, Surface Roughness,

Waviness and Lay

ASTM Documents:

ASTM E 4, Verification of Testing Machines

ASTM E 8, Tension Testing of Metallic Materials

AWS Documents:

AWS A4.3, Standard Methods for Determination of

the Diffusible Hydrogen Content of Martensitic, Bainitic,

and Ferritic Steel Weld Metal Produced by Arc Welding

10.3.3 Summary of Method. Implant testing of welded

joints is performed using a threaded rod welded into a

closely fitted hole in the test plate. A tensile load is

applied to the rod after welding. The load is maintained

until failure or for 24 h. Failure at low stresses or short

times is a qualitative indication of susceptibility to

hydrogen-induced cracking.

10.3.4 Significance

10.3.4.1 The implant test provides a measure of resis-

tance to hydrogen-assisted cracking (cold cracking) in

the HAZ of a weldment.

10.3.4.2 The implant test may be used to select the

appropriate base metal/welding consumable combination

to provide the desired cracking-resistance properties in

the as welded condition.

10.3.5 Apparatus

10.3.5.1 Apparatus for the performance of this test

must provide a means of applying and measuring a ten-

sile load on the specimen and a means to record time to

failure. If specified, a means to record acoustical emis-

sions during the test shall be provided.

10.3.5.2 The tensile load may be applied by a tensile

testing machine, a hydraulic or mechanical mechanism,

or the application of a known dead weight to the speci-

men. When direct measurement is used, the instrument

used shall be calibrated in accordance with ASTM E 4.

When a dead weight is used, the weight shall be cali-

brated in accordance with applicable national standards.

10.3.5.3 CAUTION: A restraining clamp shall be

employed to prevent potentially hazardous elastic

rebound of the implant specimen when failure occurs.

10.3.6 Specimens

10.3.6.1 The test specimen consists of a steel rod fit-

ted into a clearance hole in the center of a specimen

plate, with the top of the rod flush with the top of the sur-

face of the specimen plate (see Figure 10.3.1).

10.3.6.2 The rod shall be between 1/4 in (6 mm) and

3/8 in (10 mm) in diameter and shall be either threaded

or notched. The threaded rod is considered the preferable

configuration. When threaded, the thread shall be a uni-

fied national fine (UNF) Class 1 thread, 9/16 in (14 mm)

long, consistent with the diameter of the rod. The circular

notch may be machined in the rod in lieu of the thread.

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CLAUSE 10. WELDABILITY TESTING AWS B4.0:2007

The notch is located so as to coincide with the coarse-

grained HAZ below the weld.

10.3.6.3 The minimum recommended specimen plate

dimensions are 6 in (152 mm) wide by 8 in (203 mm)

long by 9/16 in (14 mm) thick.

10.3.7 Procedure

10.3.7.1 The rod shall be positioned in the clearance

hole in the specimen plate so that the top of the rod is

flush with the surface of the plate.

10.3.7.2 A weld bead shall be deposited on the top of

the specimen plate directly over the rod and hole.

10.3.7.3 The completed weldment shall be placed in

the apparatus, and the load shall be applied within three

minutes of the completion of welding. The elapsed time

between the completion of welding and the application

of the load shall be recorded.

10.3.7.4 The load shall be maintained until failure or

for a minimum of 24 h. Time to failure may be recorded

by any suitable means.

10.3.7.5 Notch tensile stress is equal to the load

divided by the cross-sectional area of the implant. The

area is determined by using the root diameter of the

thread or notch.

10.3.7.6 The lower critical stress is the highest stress

at which no failure occurs.

10.3.7.7 When the test is used to evaluate susceptibil-

ity to hydrogen-assisted cracking, a diffusible hydrogen

determination shall be performed for each welding pro-

cess and consumable in accordance with AWS A4.3. The

diffusible hydrogen determination shall be performed

under the same conditions as the test weld.

10.3.8 Report. Test data should be recorded on a Test

Results Sheet similar to Figure 10.3.3. In addition to the

requirements of applicable documents (see 10.3.2), the

report shall include the following for each specimen

tested:

(1) Base material specification,

(2) Implant material specification,

(3) Filler material specification/classification,

(4) Welding procedure (process and parameters),

(5) Specimen type (implant and base plate),

(6) Results of loading test:

(a) Load applied,

(b) Elapsed time to application to load,

(d) Notch tensile stress (if required),

(e) Location and time to fracture, and

(f) Acoustical emissions (if required).

(7) Ambient temperature,

(8) Relative humidity,

(9) Any observation of unusual characteristics of the

specimens or procedure, and

(10) Results of diffusible hydrogen test.

10.3.9 Commentary. If a series of tests over an appro-

priate stress range is made, the data may be plotted as

stress versus time to failure, in order to obtain a curve

similar to the one shown in Figure 10.3.2. The relative

position of this curve is a measure of the hydrogen-

assisted cracking susceptibility of the tested base metal/

welding procedure combination. A number of variations

of this test appear in the literature. The most common

variation is the thread versus the notch, which are both

permitted in this standard. Some researchers have cooled

the weldment in water before loading but this practice

does not seem to be prevalent, and the practice is not

covered in this standard. Unified National Fine (Class 1)

thread size is specified in an effort to standardize and

facilitate this test.

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AWS B4.0:2007 CLAUSE 10. WELDABILITY TESTING

Note: Bead on plate weld over specimen.

Figure 10.3.1—Implant Test Specimen and Fixture

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CLAUSE 10. WELDABILITY TESTING AWS B4.0:2007

Figure 10.3.2—Typical Data for Implant Test Series

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AWS B4.0:2007 CLAUSE 10. WELDABILITY TESTING

IMPLANT TEST RESULTS

Company Name _____________________________________________________________ Date _______________________

Job/Test No. ________________________________________________________________ Sheet _________ of __________

Description of Investigation ____________________________________________________________________________________

Base Metal Identification _______________________________ Thickness ___________________________________________

Test Plate Size ______________________________________

Base Metal Composition:

C__________ Si __________ Mn ________ P __________ S__________ Cr__________ Mo ________

Ni _________ V __________ Cu_________ Nb _________ Ca_________ B __________ Ti _________

Al _________ N __________ _________ __________ _________ __________ _________

Implant Metal Identification _____________________________ Diameter ____________________________________________

Groove Type ________________________________________ Groove Dimensions____________________________________

Implant Metal Composition:

C__________ Si __________ Mn ________ P __________ S__________ Cr__________ Mo ________

Ni _________ V __________ Cu_________ Nb _________ Ca_________ B __________ Ti _________

Al _________ N __________ _________ __________ _________ __________ _________

Welding Electrode/Wire Specification ____________________________________________________________________________

Commercial Designation _______________________________ Diameter ____________________________________________

Baking Treatment ____________________________________

Welding Procedure Spec. No. ___________________________ Welding Process ______________________________________

Shielding Gas _______________________________________ Gas Flow Rate _______________________________________

Shielding Flux _______________________________________ Flux Size ____________________________________________

Current ____________________________________________ Ambient Temp. _______________________________________

Voltage ____________________________________________ Ambient Humidity _____________________________________

Polarity ____________________________________________

Travel Speed ________________________________________

Heat Input __________________________________________

Hydrogen Determination Method ________________________________________________ Date _______________________

__________________________________________________ Result ______________________________________________

Results:

Method of Fracture Determination ______________________________________________________________________________

Lower Critical Stress _________________________________________________________________________________________

Notch Tensile Strength _______________________________________________________________________________________

Remarks __________________________________________________________________________________________________

Tested By __________________________________________________________________

Signature___________________________________________________________________ Date _______________________

Figure 10.3.3—Suggested Data Sheet for Implant Test

Specimen No.

Applied Load Time, Weld to

Load Application,

seconds

Fracture

Location

Time to Fracture,

hrs:minlb. kg

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CLAUSE 10. WELDABILITY TESTING AWS B4.0:2007

10.4 Lehigh Restraint Test

10.4.1 Scope

10.4.1.1 The Lehigh restraint test is used to create

quantitative data on solidification or hydrogen-assisted

cracking susceptibility of deposited weld metal. The

quantitative measure of weld crack susceptibility pro-

vided by this test is the degree of restraint required to

produce a weld metal crack.

10.4.1.2 This standard is applicable to the following:

(1) Investigation of the cracking susceptibility of

base plate and weld metal materials, and

(2) Research and development.

10.4.1.3 The use of this test is restricted as follows:

(1) The test is applicable only to base plate materials,

(2) A large amount of base metal is required,

(3) A series of specimens must be tested to obtain a

crack susceptibility index, and

(4) Significant specimen preparation is required.

10.4.1.4 The following information shall be furnished:

(1) Weld Procedure (process and parameters),

(2) Base metal specification including actual chemi-

cal composition,

(3) Base metal thickness,

(4) Filler metal specification and chemical composi-

tion of deposited weld metal,

(5) Report form including specific data to be re-

corded and observations to be made, and

(6) Acceptance criteria (if any).

10.4.2 Normative References. The following standards

contain provisions which, through reference in this text,

constitute mandatory provisions of this test. For undated

references, the latest edition of the referenced standard

shall apply. For dated references, subsequent amend-

ments to, or revisions of, any of these publications do not

apply.

AWS Documents:

AWS A4.3, Standard Methods for Determination of

the Diffusible Hydrogen Content of Martensitic, Bainitic,

and Ferritic Steel Weld Metal Produced by Arc Welding

10.4.3 Summary of Method

10.4.3.1 A test weld is deposited in a machined

groove in a series of flat plate test specimens. Each spec-

imen of the series is designed to provide a different

amount of restraint to the test weld.

10.4.3.2 Each test weld is examined for the presence

of weld metal cracks after the weld cools to room

temperature.

10.4.3.3 The maximum amount of restraint that is

applied without the occurrence of weld metal cracking is

deemed the index of crack susceptibility for the particu-

lar combination of base metal, filler metal and welding

parameters.

10.4.4 Significance

10.4.4.1 This test is used to examine the susceptibility

of deposited weld metal to solidification or hydrogen-

assisted cracking. The important variables that can be

investigated using this test include the base-metal compo-

sition, the filler metal composition, preheating effect,

welding heat input, weld-bead size, and shape. The test has

been used primarily for investigating the effects of weld

and base-metal composition on cracking susceptibility.

10.4.5 Definitions and Symbols. Definitions for sym-

bols used in 10.4 are as follows:

I = distance from root of the saw cut slots to the

specimen centerline

2I = level of restraint

L = length of saw cut slot

10.4.6 Apparatus. Evaluation for the presence of cracks

may require the use of metallographic equipment to sec-

tion the test weld and prepare the section for metallurgi-

cal examination.

10.4.7 Specimens

10.4.7.1 The specimen configuration is shown in Fig-

ure 10.4.1. The test weld (a single pass) is deposited in

the groove machined along the longitudinal centerline of

an 8 in (203 mm) by 12 in (305 mm) plate of the material

being examined. The weld is begun at one end of the

groove and is deposited continuously to the other end of

the groove.

10.4.7.2 The restraint is provided by the mass of the

plate surrounding the groove. The level of restraint is

controlled by sawing slots along the sides and ends of the

plate. So that each specimen of the series will provide a

different level of restraint, each specimen will have slots

of a different length (L in Figure 10.4.1). All slots along

the sides of a given specimen will be the same length.

The slots on the specimen ends will be shorter than the

side slots, but all end slots will be of equal length.

10.4.7.3 The level of restraint is inversely propor-

tional to the length of the slots and is expressed numeri-

cally as the distance between the ends of the slots (2I in

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AWS B4.0:2007 CLAUSE 10. WELDABILITY TESTING

Figure 10.4.1). Thus, as the restraint is decreased by

longer slots, the cracking index also decreases. The same

effect could be obtained by using plates of decreasing

size, but by varying the slot length, the cooling rate of the

test weld will remain constant in all specimens of the

series.

10.4.7.4 In typical series of test specimens, the speci-

men with the highest restraint will not have any slots.

The lengths of the slots of each succeeding specimen of

the series will be increased 1/4 in (6 mm) or 1/2 in

(13 mm) to provide decreasing levels of restraint.

10.4.8 Procedure

10.4.8.1 A series of specimens is welded with each

specimen providing a different level of restraint to the

test weld, i.e., each specimen will have slots of differing

length. Usually, the first test weld is deposited in the

specimen with the highest level of restraint (no periph-

eral slots). If this specimen cracks, another specimen that

provides less restraint (longer slots) is welded. Sufficient

specimens are welded each with a decreasing restraint

level until a restraint level is reached at which no weld-

metal cracking occurs. This level of restraint (2I) is

reported as the cracking index of that particular combina-

tion of material compositions, welding parameters, etc.

The cracking index is the level of restraint below which

no cracking occurs.

10.4.8.2 Examination for cracking usually can be

done visually as the crack normally appears on the sur-

face of the weld as the weld cools. If specified, the

absence of a crack should be verified by using liquid

penetrant or magnetic-particle inspection or by sectioning

the weld, polishing the section surface, and examining

this surface by low-power magnification. Examination

for hydrogen cracks should be conducted after aging at

ambient temperature for 24 h.

10.4.8.3 When the test is used to evaluate susceptibil-

ity to hydrogen-assisted cracking, a diffusible hydrogen

determination shall be performed for each welding pro-

cess and consumable in accordance with AWS A4.3. The

diffusible hydrogen determination shall be performed

under the same conditions as the test weld.

10.4.9 Report. Test data should be recorded on a Test

Results Sheet similar to Figure 10.4.2.

The test results that shall be reported include:

(1) Base metal and filler metal identification,

(2) Base metal (specimen) thickness,

(3) Welding parameters,

(4) Any preheating temperature and postweld heat

treatment,

(5) Weld-bead size and shape,

(6) Presence and length of any weld-metal cracks at

each level of restraint,

(7) Cracking index,

(8) Method of examination for the presence of

cracks, and

(9) Results of diffusible hydrogen tests, if available.

10.4.10 Commentary. There are other U.S. and ISO

test methods available whose objectives are to evaluate

the susceptibility of weld metal and consumables to

cracking. This test method is unique in that it is intended

to develop welding parameters and thermal treatments to

establish the onset of weld metal cracking in medium and

high strength alloy steel structures and components.

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