ASTM A763-15(R2021) pdf free download

ASTM A763-15(R2021) pdf free download.Standard Practices for Detecting Susceptibility to Intergranular Attack in Ferritic Stainless Steels
1. Scope
1.1 These practices cover the following four tests: 1.1.1 Practice W—Oxalic acid etch test for detecting sus- ceptibility to intergranular attack in stabilized ferritic stainless steels by classification of the etching structures (see Sections 3 – 10). 1.1.2 Practice X—Ferric sulfate-sulfuric acid test for detect- ing susceptibility to intergranular attack in ferritic stainless steels (Sections 11 – 16). 1.1.3 Practice Y—Copper-copper sulfate-50 % sulfuric acid test for detecting susceptibility to intergranular attack in ferritic stainless steels (Sections 17 – 22). 1.1.4 Practice Z—Copper-copper sulfate-16 % sulfuric acid test for detecting susceptibility to intergranular attack in ferritic stainless steels (Sections 23 – 29). 1.2 The following factors govern the application of these practices (1-6): 2 1.2.1 Practice W, oxalic acid test, is a rapid method of identifying, by simple electrolytic etching, those specimens of certain ferritic alloys that are not susceptible to intergranular corrosion associated with chromium carbide precipitation. Practice W is used as a screening test to avoid the necessity, for acceptable specimens, of more extensive testing required by Practices X, Y, and Z. See Table 1 for a listing of alloys for which Practice W is appropriate. 1.2.2 Practices X, Y, and Z can be used to detect the susceptibility of certain ferritic alloys to intergranular attack associated with the precipitation of chromium carbides or nitrides. 1.2.3 Practices W, X, Y, and Z can also be used to evaluate the effect of heat treatment or of fusion welding on suscepti- bility to intergranular corrosion.1.2.4 Table 2 lists the identification ferritic stainless steels for which data on the application ofat least one ofthe standard practices is available. 1.2.5 Some stabilized ferritic stainless steels may show high rates when tested by Practice X because of metallurgical factors not associated with chromium carbide or nitride pre- cipitation. This possibility must be considered in selecting the test method. Combinations of alloys and test methods for which successful experience is available are shown in Table 1. Application of these standard tests to the other ferritic stainless steels will be by specific agreement between producer and user. 1.3 Depending on the test and alloy, evaluations may be accomplished by weight loss determination, microscopical examination, or bend test (Sections 30 and 31). The choices are listed in Table 1. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability of regulatory limitations prior to use. For specific safety precautionary statements, see 3.2.5, Section 7, 13.1, and 19.1. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Preparation of Test Specimens
4.1 The preparation of test specimens is common among Practices X, Y, and Z. Additional requirements are noted where necessary. 4.2 A specimen having a total surface area of 5 to 20 cm 2 is recommended for Practices X, Y, and Z. As-welded specimens should be cut so that no more than 13 mm ( 1 ⁄ 2 in.) width of unaffected base metal is included on either side ofthe weld and heat-affected zone. 4.3 The intent is to test a specimen representing as nearly as possible the surface of the material as used in service. Only such surface finishing should be performed as is required to remove foreign material and obtain a standard, uniform finish as specified. For very heavy sections, specimens should be prepared to represent the appropriate surface while maintaining reasonable specimen size for convenience in testing. Ordinarily, removal of more material than necessary will have little influence on the test results. However, in the special case of surface carburization (sometimes encountered, for instance, in tubing when carbonaceous lubricants are employed) it may be possible by heavy grinding or machining to remove the carburized layer completely. Such treatment of test specimens is not permissible, except in tests undertaken to demonstrate such surface effects. 4.4 Sensitization ofTest Specimens: 4.4.1 Specimens from material that is going to be used in the as-received condition without additional welding or heat treat- ment may be tested in the as-received condition without any sensitizing treatment. 4.4.2 Specimens from material that is going to be welded or heat treated should be welded or heat treated in as nearly the same manner as the material will experience in service. 4.4.3 The specific sensitizing or welding treatment, or both, should be agreed upon between the supplier and the purchaser.