ASTM A262-02ae1

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e1
Designation: A 262 – 02a
Standard Practices for
Detecting Susceptibility to Intergranular Attack in Austenitic
1
Stainless Steels
This standard is issued under the fixed designation A 262; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1
e NOTE—Table 1 was editorially corrected in August 2004.
1. Scope* steel grades that are essentially free of susceptibility to
intergranular attack associated with chromium carbide precipi-
1.1 These practices cover the following five tests:
tates. These specimens will have low corrosion rates in certain
1.1.1 Practice A—Oxalic Acid Etch Test for Classification
corrosion tests and therefore can be eliminated (screened) from
of Etch Structures of Austenitic Stainless Steels (Sections 3 to
testing as “acceptable.”
7, inclusive),
1.4 The ferric sulfate–sulfuric acid test, the copper–copper
1.1.2 Practice B—Ferric Sulfate–Sulfuric Acid Test for
sulfate–50 %sulfuricacidtest,andthenitricacidtestarebased
Detecting Susceptibility to Intergranular Attack in Austenitic
on weight loss determinations and, thus, provide a quantitative
Stainless Steels (Sections 8 to 14, inclusive),
measureoftherelativeperformanceofspecimensevaluated.In
1.1.3 Practice C—Nitric Acid Test for Detecting Suscepti-
contrast, the copper–copper sulfate–16 % sulfuric acid test is
bility to Intergranular Attack in Austenitic Stainless Steels
based on visual examination of bend specimens and, therefore,
(Sections 15 to 21, inclusive),
classifies the specimens only as acceptable or nonacceptable.
1.1.4 Practice E—Copper–Copper Sulfate–Sulfuric Acid
1.5 In most cases either the 24-h copper–copper sul-
Test for Detecting Susceptibility to Intergranular Attack in
fate–16 % sulfuric acid test or the 120-h ferric sulfate–sulfuric
Austenitic Stainless Steels (Sections 22 to 31, inclusive), and
acid test, combined with the oxalic acid etch test, will provide
1.1.5 Practice F—Copper–Copper Sulfate–50 % Sulfuric
the required information in the shortest time. All stainless
Acid Test for Detecting Susceptibility to Intergranular Attack
grades listed in the accompanying table may be evaluated in
in Molybdenum-Bearing CastAustenitic Stainless Steels (Sec-
these combinations of screening and corrosion tests, except
tions 32 to 38, inclusive).
those specimens of molybdenum-bearing grades (for example
1.2 The following factors govern the application of these
316, 316L, 317, and 317L), which represent steel intended for
practices:
use in nitric acid environments.
1.2.1 Susceptibility to intergranular attack associated with
1.6 The 240-h nitric acid test must be applied to stabilized
theprecipitationofchromiumcarbidesisreadilydetectedinall
and molybdenum-bearing grades intended for service in nitric
six tests.
acidandtoallstainlesssteelgradesthatmightbesubjecttoend
1.2.2 Sigma phase in wrought chromium-nickel-
grain corrosion in nitric acid service.
molybdenum steels, which may or may not be visible in the
1.7 Only those stainless steel grades are listed in Table 1 for
microstructure, can result in high corrosion rates only in nitric
whichdataontheapplicationoftheoxalicacidetchtestandon
acid.
their performance in various quantitative evaluation tests are
1.2.3 Sigma phase in titanium or columbium stabilized
available.
alloys and cast molybdenum-bearing stainless alloys, which
1.8 Extensive test results on various types of stainless steels
may or may not be visible in the microstructure, can result in
2
evaluated by these practices have been published in Ref (1).
high corrosion rates in both the nitric acid and ferric sulfate-
1.9 The values stated in SI units are to be regarded as
–sulfuric acid solutions.
standard. The inch-pound equivalents are in parentheses and
1.3 The oxalic acid etch test is a rapid method of identify-
may be approximate.
ing, by simple etching, those specimens of certain stainless
1.10 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the
1
These practices are under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and RelatedAlloys and are the direct responsibility of Subcommittee
A01.14 on Methods of Corrosion Testing.
2
Current edition approved Nov. 10, 2002. Published December 2002. Originally The boldface numbers in parentheses refer to the list of references found at the
approved in 1943. Last previous edition approved in 2002 as A 262 – 02. end of these practices.
*A Summary of Changes section appears at the end of this standard.
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