Effects of Ni Concentration and Aging Heat Treatment on the Hydrogen Embrittlement Behavior of Precipitation-Hardened High-Mn Austenitic Steel

The effects of Ni concentration and dispersed conditions of vanadium carbide (VC) nano-particles on the hydrogen embrittlement (HE) behavior of precipitation-hardened high-Mn austenitic steels were investigated under the presence of thermally pre-charged hydrogen. Slow strain-rate tensile tests revealed that HE susceptibility decreased with an addition of Ni. VC precipitates functioned as the trapping sites for dissolved hydrogen, though its effect on resisting the HE was trivial. Hydrogen enhanced intergranular (IG) fracture wherein its area fraction was increased with the hardening by VC as well as with the escalation of internal hydrogen concentration. The IG fracture was the primary rationale for the hydrogen-induced loss of ductility. Possible mechanisms of the IG-related HE as well as future strategy for mitigating the mechanical degradation is discussed based on the fractographic observation and post-mortem microstructural analyses.

Automated summary

The addition of Ni was found to reduce hydrogen embrittlement sensitivity in high-Mn austenitic steels, while VC nano-particles could serve as trapping sites for dissolved hydrogen with only minor effects on hydrogen embrittlement resistance. Hydrogen enhanced intergranular fracture, with IG fracture being the primary reason for hydrogen-induced loss of ductility.