Stress Corrosion Cracking of Hydrogen-containing Austenitic Stainless Steel in H₂SO₄-NaCl Solution

Abstract

Stress corrosion cracking (SCC) of hydrogen-containing austenitic stainless steels was investigated in H₂SO₄-NaCl solution. The specimens used were exposed to 28MPa hydrogen at 673K (400°C) for 16hr. The time-to-fracture of hydrogen-containing Type 304 steel was shorter than that of hydrogen-free one in weak corrosive solution, but was longer in strong corrosive solution. And the time-to-fracture of hydrogen-containing Type 316 steel was shorter than that of hydrogen-free one even in strong corrosive solution. The susceptibility to SCC of hydrogen containing Type 304 steel decreased under the cathodic hydrogen charging. This suggests that the stress corrosion process of this steel is active path corrosion. The self-activation time of Type 304 and 316 steels in H₂SO₄ solution became shorter by hydrogenation, and deformation promoted this tendency. In an immersion test in FeCl₃ solution, Type 304 and 316 steels increased the susceptibility to pitting corrosion by hydrogenation. From these results, the change of SCC susceptibility of hydrogen-containing austenitic stainless steels might be caused by the passive film destabilization and the anodic activation of stress induced martensite.