LAUSR

The understanding of the underlying mechanism for the hydrogen embrittlement (HE) is an important issue to ensure the safety of a hydrogen-based energy system. Like type 316L stainless steel, stable austenitic steels have been used in the hydrogen industry, because of their low susceptibility to HE. Decreasing the Ni content of austenitic stainless steels not only reduces their costs but also strengthens them. However, susceptibility to HE in the austenitic steels has been reported to depend largely on the stability of the austenitic phase.1–4) The low stability of austenitic phase increases the occurrence of flat facets and quasi-cleavages in a hydrogen-rich environment,5–8) which deteriorates the mechanical properties under monotonic5–10) and cyclic11–15) loading conditions. Like type 304 stainless steel, metastable austenitic steels containing less Ni content suffer from more Crystallographic Characterisation of Hydrogen-induced Twin Boundary Separation in Type 304 Stainless Steel Using Microtensile Testing