Microstructural changes in austenitic stainless steels resulting from cathodic charging of hydrogen

Abstract

The microstructures of two austenitic stainless steels after cathodic charging of hydrogen and room temperature out gassing have been examined in the transmission electron microscope. The charging and aging cycle results in a considerable degree of faulting and transformation to α′- and ε-martensites. Although the extent of hydrogen induced transformation is atypical of the material behaviour after deformation at the same temperature, the morphology of the transformation products is similar. Observations have indicated that the surface cracking commonly encountered in austenitic stainless steels after cathodic hydrogen charging is associated primarily with the hydrogen induced ε-martensite. In an alloy which did not transform as a result of deformation, the defect structures resulting from prior cold work did not appreciably reduce the extent of faulting, twinning, and ε-martensite formation after hydrogen charging and aging.

MST/430