GB/T 4334-2020 Corrosion of metals and alloys—Test methods for intergranular corrosion of austenitic and ferritic-austenitic (duplex) stainless steels

Scope

This standard specifies the test methods for intergranular corrosion of austenitic and ferritic-austenitic (duplex) stainless steels, including the sample preparation, test solution, test equipment, test conditions and procedures, evaluation of test results, and test reports.
This standard is applicable to the evaluation of the intergranular corrosion tendency of austenitic stainless steels and ferritic-austenitic duplex stainless steels (hereinafter referred to as duplex stainless steels). It includes the following test methods:
a) Method A: 10% oxalic acid immersion test method
A screening test for intergranular corrosion of austenitic stainless steels. After the sample is electrolytically immersed in a 10% oxalic acid solution, the metallographic structure of the immersion surface is observed under a microscope to determine whether it is necessary to conduct long-term thermal acid tests such as Method B, Method C, and Method E. It can also be used as an independent intergranular corrosion test method when it is not allowed to damage the tested structural components and equipment.
b) Method B: 50% sulfuric acid-iron sulfate corrosion test method
After placing the austenitic stainless steel in a 50% sulfuric acid-iron sulfate solution and conducting a boiling test, the corrosion rate is used to evaluate the intergranular corrosion tendency.
c) Method C: 65% nitric acid corrosion test method
After placing the austenitic stainless steel in a 65% nitric acid solution and conducting a boiling test, the corrosion rate is used to evaluate the intergranular corrosion tendency.
d) Method E: Copper-cupric sulfate-16% sulfuric acid corrosion test method
After placing the austenitic stainless steel and duplex stainless steel in a copper-cupric sulfate-16% sulfuric acid solution and conducting a boiling test, the intergranular corrosion tendency is determined by bending or metallographic methods.
e) Method F: Copper-c

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