The formation of strain-induced martensite and its influence on hydrogen compatibility of metastable austenitic stainless steels: A state-of knowledge review

Austenitic stainless stainless steels (ASS) are an important type of material used in hydrogen storage and handling equipment because of their exceptional corrosion resistance and mechanical qualities. Nevertheless, the hydrogen sensitivities of metastable ASS would be a notable concern since the strain-induced martensitic transformation (SIMT) can take place during the fabrication process. Hence, we performed tensile experiments on 304L and 316L alloys containing varying amounts of Ni content, simulating actual material deformation conditions. We conducted an analysis of the impact of Ni content on SIMT and presented a detailed description of the martensite nucleation and growth process. Subsequently, we conducted an analysis of the orientation connection of the martensitic transition using TEM. Subsequently, we summarized the effects of SIMT and hydrogen on the tensile, creep, and fatigue properties of materials. It was generally observed that in a hydrogen environment, SIMT, as a high-speed diffusion channel for hydrogen, exacerbates the detrimental effect of hydrogen on the material's mechanical properties. The significance of minimizing SIMT to enhance the hydrogen performance of metastable ASS is emphasized, and this article concluded by summarizing the practical methods for reducing the SIMT: optimizing the alloy composition, controlling the deformation temperature, and using post-forming annealing treatment. Through discussion, it was concluded that controlling the deformation temperature is not recommended as a method to eliminate strain-induced martensite.