Effect of hydrogen on ductility of stable austenitic steel

Abstract

Straining in hydrogen at a pressure of2 bar, or in air after thermal charging in high pressure hydrogen, produces only minimal loss in ductility at particular strain rates for as received or solution treated samples of a stable austenitic stainless steel. However, cathodically charging at 80°C introduces a significant embrittlement that is associated with theformation during straining of brittle surface cracks whose depth increases with charging time. The latter effect is related to the depth of penetration of hydrogen and the transformation to martensite that is induced by the combined effect of hydrogen and stress. Removal of the hydrogen and the associated α martensite by subsequent vacuum annealing produces recovery of ductility. The application of a sensitising treatment before charging or testing in hydrogen gives results that are not significantly different.