Standard Practices for

Detecting Susceptibility to Intergranular Attack in Austenitic

Stainless Steels1
This standard is issued under the fixed designation A262; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.

1. Scope based on visual examination of bend specimens and, therefore,

1.1 These practices cover the following five tests: classifies the specimens only as acceptable or nonacceptable.
1.1.1 Practice A—Oxalic Acid Etch Test for Classification 1.4 The presence or absence of intergranular attack in these
of Etch Structures of Austenitic Stainless Steels (Sections 4 to tests is not necessarily a measure of the performance of the
13, inclusive), material in other corrosive environments. These tests do not
1.1.2 Practice B—Ferric Sulfate-Sulfuric Acid Test for De- provide a basis for predicting resistance to forms of corrosion
tecting Susceptibility to Intergranular Attack in Austenitic other than intergranular, such as general corrosion, pitting, or
Stainless Steels (Sections 14 to 25, inclusive), stress-corrosion cracking.
1.1.3 Practice C—Nitric Acid Test for Detecting Suscepti- NOTE 1—See Appendix X1 for information regarding test selection.
bility to Intergranular Attack in Austenitic Stainless Steels
(Sections 26 to 36, inclusive), 1.5 The values stated in SI units are to be regarded as
1.1.4 Practice E—Copper–Copper Sulfate–Sulfuric Acid standard. The inch-pound equivalents are in parentheses and
Test for Detecting Susceptibility to Intergranular Attack in may be approximate.
Austenitic Stainless Steels (Sections 37 to 46, inclusive), and 1.6 This standard does not purport to address all of the
1.1.5 Practice F—Copper–Copper Sulfate–50 % Sulfuric safety concerns, if any, associated with its use. It is the
Acid Test for Detecting Susceptibility to Intergranular Attack responsibility of the user of this standard to establish appro-
in Molybdenum-Bearing Austenitic Stainless Steels (Sections priate safety, health, and environmental practices and deter-
47 to 58, inclusive). mine the applicability of regulatory limitations prior to use.
Some specific hazards statements are given in 10.1, 20.1.1,
1.2 The Oxalic Acid Etch Test is a rapid method of
20.1.9, 31.3, 34.4, 53.1.1, and 53.1.10.
identifying, by simple etching, those specimens of certain
1.7 This international standard was developed in accor-
stainless steel grades that are essentially free of susceptibility
dance with internationally recognized principles on standard-
to intergranular attack associated with chromium carbide
ization established in the Decision on Principles for the
precipitates. These specimens will have low corrosion rates in
Development of International Standards, Guides and Recom-
certain corrosion tests and therefore can be eliminated
mendations issued by the World Trade Organization Technical
(screened) from testing as “acceptable.” The etch test is
Barriers to Trade (TBT) Committee.
applicable only to those grades listed in the individual hot acid
tests and classifies the specimens either as “acceptable” or as
“suspect.” 2. Referenced Documents
2.1 ASTM Standards:2
1.3 The ferric sulfate-sulfuric acid test, the copper–copper
A370 Test Methods and Definitions for Mechanical Testing
sulfate–50 % sulfuric acid test, and the nitric acid test are based
of Steel Products
on weight loss determinations and, thus, provide a quantitative
A380/A380M Practice for Cleaning, Descaling, and Passi-
measure of the relative performance of specimens evaluated. In
vation of Stainless Steel Parts, Equipment, and Systems
contrast, the copper–copper sulfate–16 % sulfuric acid test is
D1193 Specification for Reagent Water
E3 Guide for Preparation of Metallographic Specimens
1
These practices are under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and are the direct responsibility of Subcommittee
2
A01.14 on Methods of Corrosion Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2021. Published September 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1943. Last previous edition approved in 2015 as A262 – 15. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/A0262-15R21. the ASTM website.

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