ASTM-A262 2002

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A262-02ae3 Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels

Published By	Publication Date	Number of Pages
ASTM	2002	17

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Categories: 77.140.20 - Stainless steels, ASTM

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Description

ASTM A262-02ae3

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

ASTM A262

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 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)².

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.)

Keywords

austenitic stainless steel; copper sulfate; corrosion testing; etch structures; ferric sulfate; intergranular corrosion; nitric acid; oxalic acid

ICS Code

ICS Number Code 77.140.20 (Steels of high quality)

DOI: 10.1520/A0262-02AE03

PDF Catalog

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

Additional information

Standard Title	A262-02ae3 Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
Published Code	ASTM
Publication Date	2002
Pages Count	17
ICS Codes	77.140.20 - Stainless steels