ASTM A262-14

Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels

ABSTRACT
This specification covers the standard practices for detecting susceptibility to intergranular attack in austenitic stainless steels. These practices include five intergranular corrosion tests, namely: (1) oxalic acid etch test for classification of etch structures of austenitic stainless steels; (2) ferric sulfate-sulfuric acid test, (3) nitric acid test and (4) copper-copper sulfate-sulfuric acid test for detecting susceptibility to intergranular attack in austenitic stainless steels; and (5) copper-copper sulfate-50% sulfuric acid test for detecting susceptibility to intergranular attack in molybdenum-bearing cast austenitic stainless steels. Methods for preparing the test specimens, rapid screening tests, apparatus setup and testing procedures, and calculations and report contents are described for each testing practice. The etch structure types used to classify the specimens are: step structure, dual structure, ditch structure, isolated ferrite, interdendritic ditches, end-grain pitting I, and end-grain pitting II.
SIGNIFICANCE AND USE
6.1 Use of the etch test allows rapid acceptance of specific lots of material without the need to perform time-consuming and costly hot acid immersion tests on those lots.
SCOPE
1.1 These practices cover the following five tests:  
1.1.1 Practice A—Oxalic Acid Etch Test for Classification of Etch Structures of Austenitic Stainless Steels (Sections 4 to 13, inclusive),  
1.1.2 Practice B—Ferric Sulfate-Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections 14 to 25, inclusive),  
1.1.3 Practice C—Nitric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections 26 to 36, inclusive),  
1.1.4 Practice E—Copper–Copper Sulfate–Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections 37 to 46, inclusive), and  
1.1.5 Practice F—Copper–Copper Sulfate–50 % Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Molybdenum-Bearing Austenitic Stainless Steels (Sections 47 to 58, inclusive).  
1.2 The oxalic acid etch test is a rapid method of identifying, by simple etching, those specimens of certain stainless steel grades that are essentially free of susceptibility to intergranular attack associated with chromium carbide precipitates. These specimens will have low corrosion rates in certain corrosion tests and therefore can be eliminated (screened) from testing as “acceptable.” The etch test is applicable only to those grades listed in the individual hot acid tests and classifies the specimens either as “acceptable” or as “suspect.”  
1.3 The ferric sulfate-sulfuric acid test, the copper–copper sulfate–50 % sulfuric acid test, and the nitric acid test are based on weight loss determinations and, thus, provide a quantitative measure of the relative performance of specimens evaluated. In contrast, the copper–copper sulfate–16 % sulfuric acid test is based on visual examination of bend specimens and, therefore, classifies the specimens only as acceptable or nonacceptable.  
1.4 The presence or absence of intergranular attack in these tests is not necessarily a measure of the performance of the material in other corrosive environments. These tests do not provide a basis for predicting resistance to forms of corrosion other than intergranular, such as general corrosion, pitting, or stress-corrosion cracking.
Note 1: See Appendix X1 for information regarding test selection.  
1.5 The values stated in SI units are to be regarded as standard. The inch-pound equivalents are in parentheses and may be approximate.  
1.6 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use....

General Information

• Status: Historical
• Publication Date: 30-Jun-2014
• ICS: 77.140.20 - Stainless steels
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.14 - Methods of Corrosion Testing

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: A262 − 14
StandardPractices for
Detecting Susceptibility to Intergranular Attack in Austenitic
1
Stainless Steels
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.Anumber 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,
classifies the specimens only as acceptable or nonacceptable.
1.1 These practices cover the following five tests:
1.4 The presence or absence of intergranular attack in these
1.1.1 Practice A—Oxalic Acid Etch Test for Classification
tests is not necessarily a measure of the performance of the
of Etch Structures ofAustenitic Stainless Steels (Sections 4 to
material in other corrosive environments. These tests do not
13, inclusive),
provide a basis for predicting resistance to forms of corrosion
1.1.2 Practice B—Ferric Sulfate-Sulfuric Acid Test for De-
other than intergranular, such as general corrosion, pitting, or
tecting Susceptibility to Intergranular Attack in Austenitic
stress-corrosion cracking.
Stainless Steels (Sections 14 to 25, inclusive),
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
1.5 The values stated in SI units are to be regarded as
(Sections 26 to 36, inclusive),
standard. The inch-pound equivalents are in parentheses and
1.1.4 Practice E—Copper–Copper Sulfate–Sulfuric Acid
may be approximate.
Test for Detecting Susceptibility to Intergranular Attack in
1.6 This standard does not purport to address all of the
Austenitic Stainless Steels (Sections 37 to 46, inclusive), and
safety concerns, if any, associated with its use. It is the
1.1.5 Practice F—Copper–Copper Sulfate–50% Sulfuric
responsibility of the user of this standard to establish appro-
Acid Test for Detecting Susceptibility to Intergranular Attack
priate safety and health practices and determine the applica-
in Molybdenum-Bearing Austenitic Stainless Steels (Sections
bility of regulatory limitations prior to use. Some specific
47 to 58, inclusive).
hazardsstatementsaregivenin10.1,20.1.1,20.1.9,31.3,34.4,
1.2 The oxalic acid etch test is a rapid method of
53.1.1, and 53.1.10.
identifying, by simple etching, those specimens of certain
stainless steel grades that are essentially free of susceptibility 2. Referenced Documents
2
to intergranular attack associated with chromium carbide
2.1 ASTM Standards:
precipitates. These specimens will have low corrosion rates in
A370Test Methods and Definitions for Mechanical Testing
certain corrosion tests and therefore can be eliminated
of Steel Products
(screened) from testing as “acceptable.” The etch test is
A380/A380MPractice for Cleaning, Descaling, and Passi-
applicable only to those grades listed in the individual hot acid
vation of Stainless Steel Parts, Equipment, and Systems
tests and classifies the specimens either as “acceptable” or as
D1193Specification for Reagent Water
“suspect.”
E3Guide for Preparation of Metallographic Specimens
3
2.2 ASME Code:
1.3 The ferric sulfate-sulfuric acid test, the copper–copper
ASME Boiler & Pressure Vessel Code,Section IX
sulfate–50%sulfuricacidtest,andthenitricacidtestarebased
4
2.3 ACS Specifications:
on weight loss determinations and, thus, provide a quantitative
Reagent Chemicals,Specifications and Procedures
measureoftherelativeperformanceofspecimensevaluated.In
contrast, the copper–copper sulfate–16% sulfuric acid test is
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
1
These practices are under the jurisdiction of ASTM Committee A01 on Steel, the ASTM website.
3
StainlessSteelandRelatedAlloysandarethedirectresponsibilityofSubcommittee Available from American Society of Mechanical Engineers (ASME), ASME
A01.14 on Methods of Corrosion Testing. International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
Current edition approved July 1, 2014. Published August 2014. Originally www.asme.org.
4
approved in 1943. Last previous edition approved in 2013 as A262–13. DOI: AvailablefromAmericanChemicalSociety(ACS),1155SixteenthStreet,NW,
10.1520/A0262-14. Washington, DC 20036, http://www.acs.org
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A262 − 13 A262 − 14
Standard Practices for
Detecting Susceptibility to Intergranular Attack in Austenitic
1
Stainless Steels
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*
1.1 These practices cover the following five tests:
1.1.1 Practice A—Oxalic Acid Etch Test for Classification of Etch Structures of Austenitic Stainless Steels (Sections 34 to 713,
inclusive),
1.1.2 Practice B—Ferric Sulfate–SulfuricSulfate-Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in
Austenitic Stainless Steels (Sections 814 to 1425, inclusive),
1.1.3 Practice C—Nitric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections
1526 to 2136, inclusive),
1.1.4 Practice E—Copper–Copper Sulfate–Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic
Stainless Steels (Sections 2237 to 3146, inclusive), and
1.1.5 Practice F—Copper–Copper Sulfate–50 % Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in
Molybdenum-Bearing Austenitic Stainless Steels (Sections 3247 to 3858, inclusive).
1.2 The oxalic acid etch test is a rapid method of identifying, by simple etching, those specimens of certain stainless steel grades
that are essentially free of susceptibility to intergranular attack associated with chromium carbide precipitates. These specimens
will have low corrosion rates in certain corrosion tests and therefore can be eliminated (screened) from testing as “acceptable.”
The etch test is applicable only to those grades listed in the individual hot acid tests and classifies the specimens either as
“acceptable” or as “suspect.”
1.3 The ferric sulfate–sulfuricsulfate-sulfuric acid test, the copper–copper sulfate–50 % sulfuric acid test, and the nitric acid test
are based on weight loss determinations and, thus, provide a quantitative measure of the relative performance of specimens
evaluated. In contrast, the copper–copper sulfate–16 % sulfuric acid test is based on visual examination of bend specimens and,
therefore, classifies the specimens only as acceptable or nonacceptable.
NOTE 1—See Appendix X1 for information regarding test selection.
1.4 The presence or absence of intergranular attack in these tests is not necessarily a measure of the performance of the material
in other corrosive environments. These tests do not provide a basis for predicting resistance to forms of corrosion other than
intergranular, such as general corrosion, pitting, or stress-corrosion cracking.
NOTE 1—See Appendix X1 for information regarding test selection.
1.5 The values stated in SI units are to be regarded as standard. The inch-pound equivalents are in parentheses and may be
approximate.
1.6 This standard does not purport to address all of the safety problems,concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of
regulatory limitations prior to use. (Specific precautionary Some specific hazards statements are given in 5.610.1, 11.1.120.1.1,
11.1.920.1.9, 31.3, 34.4, 53.1.1, and 35.153.1.10.).
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 A01.14
on Methods of Corrosion Testing.
Current edition approved May 1, 2013July 1, 2014. Published June 2013August 2014. Originally approved in 1943. Last previous edition approved in 20102013 as
A262 – 10.A262 – 13. DOI: 10.1520/A0262-13.10.1520/A0262-14.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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A262 − 14
2. Referenced Documents
2
2.1 ASTM Standards:
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A380/A380M Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems
D1193 Specification for Reagent Water
E3 Guide for Preparation of Metallographic Specimens
3
2
...