ASTM A262 - 14

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

    Active Standard ASTM A262 | Developed by Subcommittee: A01.14

    Book of Standards Volume: 01.03


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    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.

    This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

    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.

    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 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. Some specific hazards statements are given in 10.1, 20.1.1, 20.1.9, 31.3, 34.4, 53.1.1, and 53.1.10.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    A370 Test Methods and Definitions for Mechanical Testing of Steel Products

    ISO Standard

    ISO3651-2 Determination of Resistance to Intergranular Corrosion of Stainless Steels--Part 2: Ferritic, Austenitic, and Ferritic-Austenitic (Duplex) Stainless Steels--Corrosion Test in Media Containing Sulfuric Acid


    ICS Code

    ICS Number Code 77.140.20 (Steels of high quality)

    UNSPSC Code

    UNSPSC Code 11171600(Stainless steel alloys)


    DOI: 10.1520/A0262-14

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