Hydrogen embrittlement mechanisms of 18Mn12Cr austenitic stainless steel under varied hydrogen charging conditions

Driven by the demand for low-cost, high-strength, hydrogen-damage-resistant materials for hydrogen storage and transportation equipment, this study investigated hydrogen embrittlement in a novel high-strength, low-Ni, high-Mn austenitic stainless steel under hydrogen pre-charging, in-situ hydrogen charging, and combined hydrogen charging. The effective hydrogen diffusion coefficient was obtained from high-temperature/high-pressure permeation tests as 9.7×10 −7 exp(-40360/RT) m 2 ·s −1 ; which was utilized to simulate hydrogen ingress during electrochemical hydrogen charging at room temperature, as well as the thermal desorption spectrum obtained during subsequent heating. The SSRT results showed that 18Mn12Cr high-Mn austenitic stainless steel exhibited hydrogen-induced ductility degradation under all three charging modes, and the degradation generally became more pronounced with increasing charging current density within each charging modes. Hydrogen-assisted localized plasticity may promote shear-band formation, while twin–grain-boundary interactions weakened boundary stability.