Keywords: hydrogen, X-ray diffraction, in situ investigation, hydrogen charging, ferritic stainless steel, hydrides, microstructure, copper alloys, microcracks, surface crevices, hydride formation
An in situ investigation of the effect of hydrogen on ferritic stainless steel
Hydrogen ingress into ferritic stainless steels causes significant changes in their microstructure, leading, among other things, to the formation of microtwins and the increase of dislocation density. These changes also lead to the formation of microcracks and surface crevices. Moreover, the absorbed hydrogen expands the lattice parameter of Cr-alloyed ferrite. The formation of hydrides in ferrite-based alloys has not been reported in the literature so far. In order to test the possibility of hydride formation in Cr-alloyed ferrite, in situ X-ray diffraction investigations during the electrolytic hydrogen charging of stainless steel with 19% Cr (Type 430L) were conducted using a specially designed cell. As a result, an additional X-ray peak was isolated, indicating a possibility of a new unstable hydride phase formation in the surface layer, where the hydrogen concentration is a maximum.