1、Designation:A76315Standard Practices forDetecting Susceptibility to Intergranular Attack in FerriticStainless Steels1This standard is issued under the fixed designation A763;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、 last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 These practices cover the following four tests:1.1.1 Practice WOxalic acid etch test for detecting sus-ceptibility to int
3、ergranular attack in stabilized ferritic stainlesssteels by classification of the etching structures(see Sections 3 10).1.1.2 Practice XFerric sulfate-sulfuric acid test for detect-ing susceptibility to intergranular attack in ferritic stainlesssteels(Sections 11 16).1.1.3 Practice YCopper-copper su
4、lfate-50%sulfuric acidtest for detecting susceptibility to intergranular attack in ferriticstainless steels(Sections 17 22).1.1.4 Practice ZCopper-copper sulfate-16%sulfuric acidtest for detecting susceptibility to intergranular attack in ferriticstainless steels(Sections 23 29).1.2 The following fa
5、ctors govern the application of thesepractices(1-6)2:1.2.1 Practice W,oxalic acid test,is a rapid method ofidentifying,by simple electrolytic etching,those specimens ofcertain ferritic alloys that are not susceptible to intergranularcorrosion associated with chromium carbide precipitation.Practice W
6、 is used as a screening test to avoid the necessity,foracceptable specimens,of more extensive testing required byPractices X,Y,and Z.See Table 1 for a listing of alloys forwhich Practice W is appropriate.1.2.2 Practices X,Y,and Z can be used to detect thesusceptibility of certain ferritic alloys to
7、intergranular attackassociated with the precipitation of chromium carbides ornitrides.1.2.3 Practices W,X,Y,and Z can also be used to evaluatethe effect of heat treatment or of fusion welding on suscepti-bility to intergranular corrosion.1.2.4 Table 2 lists the identification ferritic stainless stee
8、lsfor which data on the application of at least one of the standardpractices is available.1.2.5 Some stabilized ferritic stainless steels may show highrates when tested by Practice X because of metallurgicalfactors not associated with chromium carbide or nitride pre-cipitation.This possibility must
9、be considered in selecting thetest method.Combinations of alloys and test methods forwhich successful experience is available are shown in Table 1.Application of these standard tests to the other ferritic stainlesssteels will be by specific agreement between producer and user.1.3 Depending on the te
10、st and alloy,evaluations may beaccomplished by weight loss determination,microscopicalexamination,or bend test(Sections 30 and 31).The choices arelisted in Table 1.1.4 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the us
11、er of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For specific safetyprecautionary statements,see 3.2.5,Section 7,13.1,and 19.1.2.Referenced Documents2.1 ASTM Standards:3A370 Test Methods and Definitions
12、for Mechanical Testingof Steel Products3.Apparatus3.1 Apparatus for Practice W,Oxalic Acid Etch Test:3.1.1 Source of DCBattery,generator,or rectifier capableof supplying 15 V and 20 A.3.1.2 Ammeter,range 0 to 30 A.3.1.3 Variable Resistance,for control of specimen current.3.1.4 CathodeOne-litre stain
13、less steel beaker or suitablepiece of stainless steel.3.1.5 Electric Clamp,to hold etched specimen.1These practices are under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and RelatedAlloys and are the direct responsibility of SubcommitteeA01.14 on Methods of Corrosion Testing.Curr
14、ent edition approved March 1,2015.Published March 2015.Originallyapproved in 1979.Last previous edition approved in 2014 as A763 14.DOI:10.1520/A0763-15.2The boldface numbers in parentheses refer to the list of references appended tothese practices.3For referenced ASTM standards,visit the ASTM websi
15、te,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,P
16、O Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.6 Metallurgical Microscope,for examination of etchedstructures at 250 to 500.3.1.7 ElectrodesThe specimen is made the anode and thebeaker or other piece of stainless steel the cathode.3.1.8 ElectrolyteOxalic acid(H2C2O42H2O)reagentgrade,10 weight%solution.3.2 AparatusCommontoPracticesX,Y,andZSuplementary requirements are noted as required.3.2.1 The apparatus used is shown in Fig.1.NOTE1No substitution for this equipment may be used.Th
