Standard Practice for Determining the Susceptibility of Stainless Steels and Related Nickel-Chromium-Iron Alloys to Stress-Corrosion Cracking in Polythionic Acids

Importancia y uso:

4.1 Polythionic acids are chemically described as H₂S_xO₆, where x is usually 3, 4, or 5 (1)3 though can be more than 50 (2). These acid environments provide a way of evaluating the resistance of stainless steels and related alloys to intergranular stress corrosion cracking. Failure is accelerated by the presence of increasing amounts of intergranular precipitate. Results for the polythionic acid test have not been correlated exactly with those of intergranular corrosion tests (Test Methods G28). Also, this test may not be relevant to stress corrosion cracking in chlorides or caustic environments.

4.2 The polythionic acid environment may produce areas of shallow intergranular attack in addition to the more localized and deeper cracking mode of attack. Examination of failed specimens is necessary to confirm that failure occurred by cracking rather than mechanical failure of reduced sections.

Subcomité:

G01.06

Referida por:

G0168-17, G0030-22, G0058-85R23, G0049-85R23E01

Volúmen:

03.02

Número ICS:

77.040.10 (Mechanical testing of metals), 77.060 (Corrosion of metals)

Palabras clave:

accelerated test; nickel-chromium-iron alloys; polythionic acids; stainless steels; stress-corrosion cracking;