ASTM G58-1985(2005) Standard Practice for Preparation of Stress-Corrosion Test Specimens for Weldments《焊件的应力腐蚀试样的制备》.pdf

1、Designation: G 58 85 (Reapproved 2005)Standard Practice forPreparation of Stress-Corrosion Test Specimens forWeldments1This standard is issued under the fixed designation G 58; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the ye

2、ar of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers procedures for the making andutilization of test specimens for the evaluation of weldments

3、 instress-corrosion cracking (SCC) environments.1.2 Test specimens are described in which (a) stresses aredeveloped by the welding process only, (b) stresses aredeveloped by an externally applied load in addition to thestresses due to welding, and (c) stresses are developed by anexternally applied l

4、oad only with residual welding stressesremoved by annealing.1.3 This practice is concerned only with the welded testspecimen and not with the environmental aspects of stress-corrosion testing. Specific practices for the bending and load-ing of test specimens, as well as the stress considerationsinvo

5、lved in preparation of C-rings, U-bend, bent-beam, andtension specimens are discussed in other ASTM standards.1.4 The actual stress in test specimens removed fromweldments is not precisely known because it depends upon thelevel of residual stress from the welding operation combinedwith the applied s

6、tress. A method for determining the magni-tude and direction of residual stress which may be applicable toweldment is described in Test Method E 837. The reproduc-ibility of test results is highly dependent on the preparation ofthe weldment, the type of test specimen tested, and theevaluation criter

7、ia used. Sufficient replication should be em-ployed to determine the level of inherent variability in thespecific test results that is consistent with the objectives of thetest program.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the

8、responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (For more specificsafety hazard information, see Section 7.)2. Referenced Documents2.1 ASTM Standards:2E8 Test Methods for Tensio

9、n Testing of Metallic MaterialsE 399 Test Method of Plane-Strain Fracture Toughness ofMetallic MaterialsE 837 Test Method for Determining Residual Stresses bythe Hole-Drilling Strain-Gage MethodG1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test SpecimensG30 Practice for Making and U

10、sing U-Bend Stress-Corrosion Test SpecimensG35 Practice for Determining the Susceptibility of Stain-less Steels and Related Nickel-Chromium-Iron Alloys toStress-Corrosion Cracking in Polythionic AcidsG36 Practice for Performing Stress-Corrosion CrackingResistance of Metals and Alloys in a Boiling Ma

11、gnesiumChloride SolutionG37 Practice for Use of Mattssons Solution of pH 7.2 toEvaluate the Stress-Corrosion Cracking Susceptibility ofCopper-Zinc AlloysG38 Practice for Making and Using C-Ring Stress Corro-sion Test SpecimenG39 Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Spe

12、cimensG44 Practice for Exposure of Metals and Alloys in Neutral3.5 % Sodium Chloride SolutionG49 Practice for Preparation and Use of Direct TensionStress-Corrosion Test Specimens3. Summary of Practice3.1 The following summarizes the test objectives that maybe evaluated:3.1.1 Resistance to SCC of a t

13、otal weldment (weld, heat-affected zone, and parent metal) as produced by a specificwelding process;1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals, and is the direct responsibility of Subcommittee G01.06 on Environmen-tally Assisted Cracking.Current edition appr

14、oved May 1, 2005. Published May 2005. Originallyapproved in 1985. LAst previous editiona pproved in 1999 as G 58 85 (1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, re

15、fer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 Resistance to SCC of deposited weld metal;3.1.3 Determination of a stress level or stress intensity thatwill produce

16、SCC in a weldment;3.1.4 Evaluation of SCC failure in the specific zones of aweld (weld metal, partially melted zone, weld interface,heat-affected zone, and base metal); and3.1.5 Evaluation of the effect of notches and stress raisers inweldments.4. Significance and Use4.1 The intent of this practice

17、is to indicate standard weldedspecimens and welding procedures for evaluating the SCCcharacteristics of weldments in corrosive environments. Thepractice does not recommend the specific corrosive media thatmay be selected by the user depending upon the intent of hisinvestigation. Specific corrosive m

18、edia are included in Prac-tices G 35, G 36, G 37, and G 44. Other environments can beused as required.5. Types of Specimens and Specific Applications5.1 This practice covers the following procedures for thepreparation of test weldments. The form of the material to beevaluated (plate, bar, tubing, ca

19、sting, or forging) may deter-mine whether its usage is applicable in a given test. Residualwelding stresses may be left intact or they may be fully orpartially removed by an appropriate heat treatment.5.1.1 Flat Welding (Fig. 1)This weldment (1)3is appli-cable for all tension and bend specimens. The

20、 size of theweldment may be varied according to the needs of the user orthe demands of welding practice being evaluated. It is appli-cable to any welding procedure and can involve single- ormultiple-pass welds.5.1.2 Circular Bead Weldment (Fig. 2)This weldment (2,3, 4, 5) measures the tendency for S

21、CC in the base metal,heat-affected zone, and deposited weld metal. The circularweld develops residual stresses. It is applicable to any materialform (plate, bar, castings) that can be machined to therecommended size. The welding procedure involves one cir-cular stringer bead deposit of weld metal.5.

22、1.3 Bead-on-Bar Weldment (Fig. 3)This weldment (2)measures the tendency for SCC of the base metal. Thelongitudinal fusion welds develop residual stresses on the bar.It is applicable to materials that can be machined to approxi-mately a 25-mm or 1-in. round.5.1.4 Direct Tension Weldments (Fig. 4)Thes

23、e weldments(3, 4, 5) measure the cracking tendency in weld metal, basemetal, or heat-affected zone. The applied stress is developed inuniaxially loaded tension specimens. Notches may be intro-duced into the weld metal, base metal, or heat-affected zone.The tension specimens are machined from welded

24、plate or castsections (Fig. 1) and may be made exclusively from weldmetal.5.1.5 U-Bend Weldment (Fig. 5)This weldment (5, 6)measures crack tendency in the weld, base metal, andheataffected zone. The bending operation after welding createshigh levels of elastic and plastic strain resulting in a wide

25、rangeof stresses in a single specimen. The presence of residualwelding stresses make this a most severe test procedure. It is3The boldface numbers in parentheses refer to the list of references at the end ofthis practice.Procedure:(a) Specimen sizeas required.(b) Note grain direction and weld longit

26、udinally or across grain.(c) For multiple-pass welds, grind between passes. Use back gouging fromopposite side to attain 100 % weld penetration.(d) Discard weld ends.(e) Remove test sections as required. Sections may be taken across the weld orlongitudinally with the weld.FIG. 1 Flat WeldmentProcedu

27、re:(a) Specimen size: 100 by 100 by 3 to 12 mm (4 by 4 by18 to12 in.)(b) Clamp or tack weld the edges of the test specimen to a base plate to obtainrestraint.(c) Weld a 50-mm or 2-in. diameter circular bead using the selected weld process(Table 1).(d) Examine both sides of specimen after exposure.FI

28、G. 2 Circular Bead WeldmentG 58 85 (2005)2applicable to any material that can be formed into a U-shapewithout mechanical cracking or localized bending in theheataffected zone.5.1.6 Bent-Beam Weldment (Fig. 6)This weldment (4, 5,6) measures cracking tendency in the weld bead, the weldbasemetal interf

29、ace, and heat-affected zone due to stress concen-tration. The specimen will contain residual welding stressesand stresses due to elastic strain produced by bending. Thisspecimen is particularly applicable to materials that cannot bebent into a U-shape.5.1.7 Precracked Cantilever Beam Weldment (Fig.

30、7)Thisweldment (5) measures the level of stress intensity to producecrack initiation or propagation in various areas of a weldment.Notches or cracks may be introduced into the weld metal, basemetal, or heat-affected zone. The specimen will contain re-sidual welding stresses and applied stresses. Wel

31、dments maybe prepared in accordance with Fig. 1 or by means of theK-preparation for multiple-pass welds (Fig. 11 and Ref (7).5.1.8 Tuning Fork Weldment (Fig. 8)This weldment (5, 8)measures cracking tendency in the base metal, heat-affectedzone, or weld-base metal interface if the weld reinforcement

32、isnot removed. When the reinforcement is removed, crackingmay also occur in the weld metal, depending on the suscepti-bility of the three zones of the weldment and the coincidenceProcedure:(a) Specimen size: 25-mm (1 in.) diameter by 150 mm (6 in.) long.(b) Fusion weld (GTAW) entire length on opposi

33、te sides.(c) Discard 6 mm or14 in. from ends and remove 20-mm or34-in. test specimens.(d) Examine cross section for radial cracking.FIG. 3 Bead-on-Bar WeldmentProcedure:(a) Direct tension specimens to be machined directly from flat plate weldment (Fig. 1).(b) See Practice G49and Test Methods E8for r

34、ecommended dimensions.FIG. 4 Direct Tension WeldmentsProcedure:(a) U-bend specimens to be machined directly from flat plate weldment (Fig. 1)(b) See Practice G30for bending method.NOTE 1The welds may be oriented 90 to the direction shown.FIG. 5 U-Bend WeldmentG 58 85 (2005)3of maximum stress with th

35、e base metal, heat-affected zone, orweld metal. Stresses are applied by closing the tines of the fork,and the toe of the weld acts as a metallurgical notch. Tuning-fork specimens may also be machined exclusively from weldmetal.5.1.9 Cruciform Weldment (Fig. 9)This weldment (9) willdevelop the highes

36、t degree of weld restraint and residual weldstresses. It has been used for evaluating the susceptibility ofhigh-strength steel and armor plate to underbead cracking inthe heat-affected zone of the weld. The welding sequence willProcedure:(a) Bent-beam specimens to be machined directly from flat plat

37、e weldment. (Fig. 1).Fulcrum should be notched so as not to contact weld bead.(b) Dimensions: as required.(c) See Practice G39for stress calculations.NOTE 1The welds may be oriented 90 to the direction shown.FIG. 6 Bent-Beam WeldmentProcedure:(a) Specimens may be machined from flat plate weldment (F

38、ig. 1)orK-weldpreparation (Fig. 11).(b) See Test Method E 399 and Ref (13).FIG. 7 Precracked Cantilever Beam WeldmentProcedure:(a) Specimens are machined from parent metal and machined to shape.(b) Weld bead is applied across the test specimen at the base of one tine.(c) Either style specimen is app

39、ropriate for this test.FIG. 8 Tuning Fork WeldmentProcedure:(a) The dimensions of the plate sections may be varied to suit the needs of thematerial under study.(b) To obtain maximum and uniform weld restraint it is essential to grind all matingsurfaces flat. The ground area should be extended to cov

40、er the test weld area.(c) Weld in sequence shown. The number of passes may be varied to suit theneeds of the test.(d) Remove and discard 6.4 mm (12 in.) on both ends and section tests specimensas required.FIG. 9 Cruciform WeldmentG 58 85 (2005)4produce an increasing degree of restraint with each suc

41、cessiveweld pass. The number of passes may be varied. Sections aretaken from the weldment and if not already cracked may beexposed to SCC environments.5.1.10 C-Ring and Slit Tubing Weldments (Fig. 10)Theseweldments (2, 4, 5) measure the cracking tendency in the weld,base metal, and heat-affected zon

42、e. In the C-ring test (PracticeG38), the stress is applied externally. In the slit tubing test, thestress is applied by a wedge that is forced into the slit section.While any material form can be machined into a ring section,this test is specifically designed for tubing.5.1.11 K-Weld Preparation (Fi

43、g. 11)This weldment (7)was specifically designed to test the stress-corrosion crackingtendency in various zones of a multiple-pass weld. Notches aremade in the weld metal, weld interface, heat-affected zone, orparent metal of cantilever beam-type specimens (Fig. 7). Thenotches serve as stress concen

44、trators.NOTE 1Calculated stresses developed in beam specimens, C-rings,and so forth. with weld beads intact will not accurately represent stressesgenerated in fillets at the edge of the weld beads and in relatively thickbeads, and strain gages will be needed if precise values of the appliedstress ar

45、e required. The effective stress of course will be the algebraic sumof the applied stress and residual welding stresses.NOTE 2Calculated stresses also may be erroneous for bead-offspecimens of weldments of dissimilar alloys or in the case of relativelysoft heat-affected zones.6. Welding Consideratio

46、ns6.1 The choice of a welding method and the application ofproper welding techniques are major factors influencing theoverall corrosion resistance of a weldment. Each weldingmethod as described in Refs (10, 11) has its own inherentcharacteristics which will govern the overall quality of theweld. The

47、 welding method must therefore be carefully selectedProcedure:(a) Use plate, bar, tube, or pipe of suitable size from which C-ring specimens can be machined.(b) Weld one side for the entire length before cutting slot. The weld bead may be applied in a 60 groove to obtain 100 % weld penetration or it

48、 may be appliedon the surface only. Cut slot after machining plate or bar to form tube.(c) Discard 6.4 mm (14 in.) on both ends and remove 25-mm (1-in.) long test specimens.(d) For slit tubing test, machine a thin slit in the side opposite weld. Stress may be applied by forcing a wedge or block in t

49、he slit.(e) For C-ring dimension and loading see Practice G38.FIG. 10 Slit Tubing and C-Ring WeldmentsProcedure:(a) Double bevel groove butt-weld preparation.(b) Vertical face buttered with filler metal.(c) Weld joint completed with multiple passes of filler metal.(d) Joint machined and notched as required.(e) See Ref (7).FIG. 11 K-Weld PreparationG 58 85 (2005)5and monitored since it will be the governing parameter in theprocedure and may introduce a number of variables that willaffect test results.6.2 Typical welding methods that are applicable to t