ASTM G58-1985(2011) Standard Practice for Preparation of Stress-Corrosion Test Specimens for Weldments《焊件的应力腐蚀试样的制备标准操作规程》.pdf

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1、Designation: G58 85 (Reapproved 2011)Standard Practice forPreparation of Stress-Corrosion Test Specimens forWeldments1This standard is issued under the fixed designation G58; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year

2、 of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () 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 in

3、stress-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 load

4、 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 considerationsinvolve

5、d 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 stre

6、ss. A method for determining the magni-tude and direction of residual stress which may be applicable toweldment is described in Test Method E837. The reproducibil-ity of test results is highly dependent on the preparation of theweldment, the type of test specimen tested, and the evaluationcriteria u

7、sed. Sufficient replication should be employed todetermine the level of inherent variability in the specific testresults that is consistent with the objectives of the test program.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespo

8、nsibility 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 hazards information, see Section 7.)2. Referenced Documents2.1 ASTM Standards:2E8 Test Methods for Tension Te

9、sting of Metallic MaterialsE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE837 Test Method for Determining Residual Stresses by theHole-Drilling Strain-Gage MethodG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG30 Practice for

10、 Making and Using U-Bend Stress-Corrosion Test SpecimensG35 Practice for Determining the Susceptibility of StainlessSteels and Related Nickel-Chromium-Iron Alloys toStress-Corrosion Cracking in Polythionic AcidsG36 Practice for Evaluating Stress-Corrosion-Cracking Re-sistance of Metals and Alloys in

11、 a Boiling MagnesiumChloride 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-Corrosion Test SpecimensG39 Practice for Preparation and Use of Bent-Beam Stress-Corro

12、sion Test SpecimensG44 Practice for Exposure of Metals and Alloys by Alter-nate Immersion in Neutral 3.5 % Sodium Chloride Solu-tionG49 Practice for Preparation and Use of Direct TensionStress-Corrosion Test Specimens3. Summary of Practice3.1 The following summarizes the test objectives that maybe e

13、valuated:3.1.1 Resistance to SCC of a total 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

14、Assisted Cracking.Current edition approved March 1, 2011. Published April 2011. Originallyapproved in 1985. Last previous edition approved in 2005 as G5885(2005). DOI:10.1520/G0058-85R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servicea

15、stm.org. For Annual Book of ASTMStandards volume information, refer 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 Deter

16、mination of a stress level or stress intensity thatwill produce 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 inw

17、eldments.4. Significance and Use4.1 The intent of this practice 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 dep

18、ending upon the intent of hisinvestigation. Specific corrosive media are included in Prac-tices G35, G36, G37, and G44. 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

19、 form of the material to beevaluated (plate, bar, tubing, casting, 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 weldmen

20、t (1)3is appli-cable for all tension and bend specimens. The 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 (

21、Fig. 2)This weldment (2,3, 4, 5) measures the tendency for SCC 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 i

22、nvolves one cir-cular stringer bead deposit of weld metal.5.1.3 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-m

23、m or 1-in. round.5.1.4 Direct Tension Weldments (Fig. 4)These 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-a

24、ffected zone.The tension specimens are machined from welded 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 createshi

25、gh levels of elastic and plastic strain resulting in a wide rangeof stresses in a single specimen. The presence of residualwelding stresses make this a most severe test procedure. It isapplicable to any material that can be formed into a U-shapewithout mechanical cracking or localized bending in the

26、heataffected zone.5.1.6 Bent-Beam Weldment (Fig. 6)This weldment (4, 5,6) measures cracking tendency in the weld bead, the weldbasemetal interface, and heat-affected zone due to stress concen-tration. The specimen will contain residual welding stressesand stresses due to elastic strain produced by b

27、ending. Thisspecimen is particularly applicable to materials that cannot bebent into a U-shape.5.1.7 Precracked Cantilever Beam Weldment (Fig. 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 i

28、ntroduced into the weld metal, basemetal, or heat-affected zone. The specimen will contain re-sidual welding stresses and applied stresses. Weldments maybe prepared in accordance with Fig. 1 or by means of theK-preparation for multiple-pass welds (Fig. 8 and Ref (7).5.1.8 Tuning Fork Weldment (Fig.

29、9)This weldment (5, 8)measures cracking tendency in the base metal, heat-affectedzone, or weld-base metal interface if the weld reinforcement 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 weldmen

30、t and the coincidence3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.Procedure:(a) Specimen sizeas required.(b) Note grain direction and weld longitudinally or across grain.(c) For multiple-pass welds, grind between passes. Use back gouging fromopposite

31、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 WeldmentG58 85 (2011)2of maximum stress with the base metal, heat-affected zone, orweld metal. Stresses are applied by cl

32、osing 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. 10)This weldment (9)will develop the highest degree of weld restraint and residualweld stresses. It has been used fo

33、r evaluating the susceptibilityof high-strength steel and armor plate to underbead cracking inthe heat-affected zone of the weld. The welding sequence willproduce an increasing degree of restraint with each successiveweld pass. The number of passes may be varied. Sections aretaken from the weldment

34、and if not already cracked may beexposed to SCC environments.5.1.10 C-Ring and Slit Tubing Weldments (Fig. 11)Theseweldments (2, 4, 5) measure the cracking tendency in the weld,base metal, and heat-affected zone. In the C-ring test (PracticeG38), the stress is applied externally. In the slit tubing

35、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 (Fig. 8)This weldment (7)was specifically designed to test the stress-corrosion crackingtende

36、ncy 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 concentrators.NOTE 1Calculated stresses developed in beam specimens, C-rings,and so forth. with w

37、eld 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 are required. The effective stress of course will be the algebraic sumof the applied stress a

38、nd 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.Procedure:(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 th

39、e 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.FIG. 2 Circular Bead WeldmentProcedure:(a) Specimen size: 25-mm (1 in.) diameter by 150 mm (6 in.) long.(b) F

40、usion weld (GTAW) entire length on opposite 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)

41、 See Practice G49 and Test Methods E8 for recommended dimensions.FIG. 4 Direct Tension WeldmentsG58 85 (2011)36. Welding Considerations6.1 The choice of a welding method and the application ofproper welding techniques are major factors influencing theoverall corrosion resistance of a weldment. Each

42、weldingmethod as described in Refs (10, 11) has its own inherentcharacteristics which will govern the overall quality of theweld. The welding method must therefore be carefully selectedand monitored since it will be the governing parameter in theprocedure and may introduce a number of variables that

43、 willaffect test results.6.2 Typical welding methods that are applicable to thispractice are listed in Table 1.6.3 Variables introduced by the welding method are (a) theamount of heat input introduced by the specific weldingprocess and its effect on microstructure of the weld nugget,weld interface,

44、and heat-affected zone of the parent metal, (b)localized variations in chemical composition developed duringmelting and solidification, (c) the possible pick-up of nitrogen,carbon, silicon, fluorine, or other impurities from surfacecontamination, slag, electrode coatings, fluxes, or directly fromthe

45、 atmosphere, (d) loss of elements across the welding arc (forexample, chromium), (e) secondary precipitation and otherpossible reactions occurring at areas of extremely high heatinput, and (f) porosity, shrinkage cracks, or other weld discon-tinuities introduced by the welding technique (12).7. Haza

46、rds7.1 Certain of the specimen types when made from highstrength materials, especially in thick sections with highapplied bonds, may exhibit high rates of crack propagation, andProcedure:(a) U-bend specimens to be machined directly from flat plate weldment (Fig. 1)(b) See Practice G30 for bending me

47、thod.NOTE 1The welds may be oriented 90 to the direction shown.FIG. 5 U-Bend WeldmentProcedure:(a) Bent-beam specimens to be machined directly from flat plate weldment. (Fig. 1).Fulcrum should be notched so as not to contact weld bead.(b) Dimensions: as required.(c) See Practice G39 for stress calcu

48、lations.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 (Fig. 1)orK-weldpreparation (Fig. 8).(b) See Test Method E399 and Ref (13).FIG. 7 Precracked Cantilever Beam WeldmentG58 85 (2011)4a specimen ma

49、y splinter into several pieces. Due to highstresses in a specimen, these pieces may fly off at high velocityand can be dangerous. Personnel installing and examiningspecimens should be cognizant of this possibility and beprotected against injury.8. Weldment and Test Specimen Preparation8.1 Material ParametersThe test material should be iden-tified as to method of manufacture (plate, sheet, bar, forging,static casting, centrifugal casting, precision casting, powderProcedure:(a) Double bevel groove butt-weld preparation.(b) Vertical face buttered with filler