ASTM A262-15 Standard Practices for Determining Intergranular Susceptibility to Attack in Austenitic Stainless Steels

The following test methods are defined in the ASTM A262-15 standard developed by the American Testing and Materials Organization (ASTM):

• Method A - Oxalic acid etching for classification of etching structures of austenitic stainless steels
• Method B - Ferric sulfate/sulfuric acid test for susceptibility to intergranular attack in austenitic stainless steels
• Method C - Nitric acid test for determination of susceptibility to intergranular attack in austenitic stainless steels
• Method E – Copper/copper sulfate/sulfuric acid test for susceptibility to intergranular attack in austenitic stainless steels
• Method F - Copper/copper sulfate/50 percent sulfuric acid testing for susceptibility to intergranular attack in austenitic stainless steels bearing molybdenum

The oxalic acid abrasion test is a rapid method of identifying, by simple etching, samples of certain stainless steel grades that are essentially insensitive to intergranular attack associated with chromium carbide precipitates. These samples have low corrosion rates in certain corrosion tests. Therefore, it can be removed from the test as acceptable. The abrasion test is valid only for the grades listed in the individual hot acid tests and samples are classified as acceptable.

The ferric sulfate/sulfuric acid test, the copper/copper sulfate/50 percent sulfuric acid test, and the nitric acid test are based on weight loss determinations. It therefore provides a quantitative measure of the relative performance of the samples evaluated. In contrast, the copper/copper sulfate/16 percent sulfuric acid test is based on visual inspection of bending specimens. Therefore, their samples are only classified as acceptable or unacceptable.

The presence or absence of intergranular attack in these test methods is not a measure of the material's performance in other corrosive environments. These tests do not provide a basis for estimating resistance to non-intergranular forms of corrosion such as general corrosion, pitting, or stress-corrosion cracking.

The use of abrasion testing allows certain batches of material to be accepted quickly without the need to perform time-consuming and costly hot acid dip tests on those batches.

Among the numerous tests, measurements, analyses, and evaluations our organization provides for businesses in various sectors, we also offer testing services for determining susceptibility to intergranular attack in austenitic stainless steels under the ASTM A262-15 standard, utilizing a trained and expert staff and advanced technological equipment.