The role of retained austenite in hydrogen embrittlement of supermartensitic stainless steel

Retained austenite may play a role in the hydrogen embrittlement process because austenite has much higher hydrogen solubility than martensite has. The effect of the retained austenite on hydrogen cracking was investigated by tensile testing of standard round bar specimens that had been heat treated in order to achieve different levels of retained austenite. A significant effect of the retained austenite was observed. Samples with high amounts of retained austenite experienced a much higher reduction in ductility after hydrogen charging than samples with low amounts of retained austenite. In order to explain this effect, the hydrogen solubility of samples containing different levels of austenite and precipitates was measured. This was achieved by charging the samples to saturation in an electrolyte and performing hydrogen analysis.