ASTM-A262 2008

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A262-02a(2008) Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels

Published By	Publication Date	Number of Pages
ASTM	2008	17

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Categories: 77.140.20 - Stainless steels, ASTM

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Description

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 3 to 7, inclusive),

1.1.2 Practice B Ferric Sulfate Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections 8 to 14, inclusive),

1.1.3 Practice C Nitric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections 15 to 21, inclusive),

1.1.4 Practice E Copper Copper Sulfate Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Sections 22 to 31, inclusive), and

1.1.5 Practice F Copper Copper Sulfate 50 % Sulfuric Acid Test for Detecting Susceptibility to Intergranular Attack in Molybdenum-Bearing Cast Austenitic Stainless Steels (Sections 32 to 38, inclusive).

1.2 The following factors govern the application of these practices:

1.2.1 Susceptibility to intergranular attack associated with the precipitation of chromium carbides is readily detected in all six tests.

1.2.2 Sigma phase in wrought chromium-nickel-molybdenum steels, which may or may not be visible in the microstructure, can result in high corrosion rates only in nitric acid.

1.2.3 Sigma phase in titanium or columbium stabilized alloys and cast molybdenum-bearing stainless alloys, which may or may not be visible in the microstructure, can result in high corrosion rates in both the nitric acid and ferric sulfate sulfuric acid solutions.

1.3 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.

1.4 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.

1.5 In most cases either the 15-h copper copper sulfate 16 % sulfuric acid test or the 120-h ferric sulfate sulfuric acid test, combined with the oxalic acid etch test, will provide the required information in the shortest time. All stainless grades listed in the accompanying table may be evaluated in these combinations of screening and corrosion tests, except those specimens of molybdenum-bearing grades (for example 316, 316L, 317, and 317L), which represent steel intended for use in nitric acid environments.

1.6 The 240-h nitric acid test must be applied to stabilized and molybdenum-bearing grades intended for service in nitric acid and to all stainless steel grades that might be subject to end grain corrosion in nitric acid service.

1.7 Only those stainless steel grades are listed in Table 1 for which data on the application of the oxalic acid etch test and on their performance in various quantitative evaluation tests are available.

1.8 Extensive test results on various types of stainless steels evaluated by these practices have been published in Ref (1) .

1.9 The values stated in SI units are to be regarded as standard. The inch-pound equivalents are in parentheses and may be approximate.

1.10 This standard does not purport to address all of the safety problems, 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 statements are given in 5.6, 11.1.1, 11.1.9, and 35.1.)

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PDF Pages	PDF Title
1	Scope
2	Referenced Documents Scope Apparatus TABLE 1
3	Preparation of Test Specimens TABLE 2
4	Classification of Etch Structures FIG. 1 FIG. 2 FIG. 3
5	Use of Etch Structure Classifications FIG. 4 FIG. 5 FIG. 6 FIG. 7
6	Scope Rapid Screening Test TABLE 3
7	Apparatus Ferric Sulfate–Sulfuric Acid Test Solution Preparation of Test Specimens FIG. 8
8	Procedure Calculation and Report Scope
9	Rapid Screening Test Apparatus Nitric Acid Test Solution Preparation of Test Specimens TABLE 4 FIG. 9
10	Procedure Calculation and Report
11	Scope Rapid Screening Test Summary of Practice Apparatus Acidified Copper Sulfate Test Solution Copper Addition TABLE 5
12	Specimen Preparation Test Conditions Bend Test TABLE 6
13	Evaluation FIG. 10 FIG. 11
14	FIG. 12 FIG. 13
15	Scope Rapid Screening Test Apparatus Copper–Copper Sulfate–50 % Sulfuric Acid Test Solution Preparation of Test Specimens Procedure TABLE 7
16	Calculation and Report Keywords REFERENCES

Additional information

Standard Title	A262-02a(2008) Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
Published Code	ASTM
Publication Date	2008
Pages Count	17
ICS Codes	77.140.20 - Stainless steels

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