A different type of intergranular corrosion facilitated by hydrogen in austenitic stainless steel

This research aims to investigate the distribution of hydrogen and hydrogen-facilitated intergranular corrosion (IGC) in an austenitic stainless steel, which comprises mainly Σ3 and random grain boundaries. The coherent twin boundaries Σ3, which routinely exhibited excellent corrosion resistance, were observed to be prone to IGC after hydrogen charging. Furthermore, the results demonstrated that the inhomogeneous distribution of absorbed hydrogen finally induced IGC at grain boundaries in both the solution-treated and sensitized specimens. The mechanism of hydrogen-facilitated IGC differs from the conventional chromium-depleted theory. A model was established to describe this different type of IGC induced by hydrogen.