This standard specifies specimen, test solution, test equipment, test conditions and procedure, assessment and report of the result of test methods for intergranular corrosion of stainless steel.
This standard applies to the test of intergranular corrosion of stainless steel and covers the following test methods:
a) Method A - method of 10 percent oxalic acid etch test for stainless steels.
It is applicable to screening test for intergranular corrosion of austenitic stainless steel. The specimen is electrolytically etched in 10% oxalic acid solution and then the metallographic structure of the etched surface examined under a microscope to determine whether long-time hot acid tests (Method B, C, D and E) are necessary.
It can also be performed as independent intergranular corrosion test method on occasion that damages on tested structural parts and equipment are not permissible.
b) Method B - stainless steels-method of ferric sulfate-sulfuric acid corrosion test.
It is applicable to the assessment of intergranular corrosion tendency through corrosion rate after austenitic stainless steel is boiled in sulfuric acid - ferric sulfate solution.
c) Method C - method of 65% nitric acid test for stainless steels.
It is applicable to the assessment of intergranular corrosion tendency through corrosion rate after austenitic stainless steel is boiled in 65% nitric acid solution.
d) Method D - method of nitric-hydrofluoric acid test for stainless steels
It is applicable to the assessment of the intergranular corrosion tendency of austenitic stainless steel containing molybdenum. Intergranular corrosion tendency is judged by the ratio of corrosion rate of 10% nitric acid-3% hydrofluoric acid solution (70 ℃) to that of authentic specimen.
e) Method E - stainless steels-method of copper sulfate-sulfuric acid corrosion test
It is applicable to the assessment of intergranular corrosion tendency of austenite and austenite-ferrite stainless steel through bend or metallographic method after the austenite and austenite-ferrite stainless steel are boiled in copper sulfate-sulfuric acid solution containing copper filings.
