Design principles for hydrogen-embrittlement-resistant FCC alloys: solution-treated steels and Ni-Cr-Fe alloys -An...

In this study, we reviewed the factors affecting the hydrogen embrittlement susceptibility of solution-treated austenitic steels and Ni-Cr (-Fe) alloys with face-centered cubic (FCC) structures. These alloy systems exhibit many microstructural similarities; however, when hydrogen is introduced, they display numerous differences. These differences can be explained in terms of FCC phase stability, dislocation slip planarity, deformation twinnability, and grain boundary strength. Although these factors have been clarified in various studies, they are not comprehensively understood across a wide range of chemical compositions. Recent studies have measured numerous hydrogen embrittlement data in FCC alloys and characterized the elemental effects on relevant metallurgical data, such as phase stability, grain boundary strength, stacking fault energy, and atomistic interactions. Therefore, we summarized and correlated the data to establish a comprehensive alloy design strategy for hydrogen-resistant steels and Ni alloys. Furthermore, the effect of grain refinement and related insights are also discussed toward developing high-strength hydrogen-resistant FCC alloys.