The effects of replacing Ni with Mn on hydrogen embrittlement in Cr-Ni-Mn-N austenitic steels

Abstract

Hydrogen embrittlement (HE) in Cr-Ni-Mn-N austenitic stainless steels was investigated when Ni was replaced with the equivalent Mn concentration while maintaining a constant Ni equivalent Ni-eq. Although Ni and Mn have similar effects on Ni-eq, the tendency for strain-induced martensite (SIM) transformation and H redistribution was controlled by stacking fault energy, which depended on the relative concentrations of Ni and Mn, and on the degree of H pre-charging. H transport along dislocations caused H-2 out-gassing during deformation, and H trapping at austenite/SIM interfaces increased HE. Replacing Ni with Mn reduced the stability of austenite and increased the HE susceptibility.