Comparative study on hydrogen embrittlement resistance in additive manufactured and forged austenitic stainless steel

In this work, the hydrogen embrittlement resistance of additively manufactured (AM) and conventionally manufactured (CM) Cr21Ni6Mn9N (21−6−9) stainless steels were comparatively investigated. The mechanical properties and microstructure evolution of both AM and CM conditions were studied using slow strain rate tensile tests and microanalytical techniques such as scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and electron channeling contrast imaging (ECCI). The results indicated that compared to the CM condition, the AM stainless steel demonstrated enhanced resistance to hydrogen embrittlement, coupled with a reduction in plasticity loss. The primary factor contributing to this resistance was identified as an increased occurrence of deformation twinning in both steels after hydrogen charging. The superior resistance observed in the AM stainless steel was attributed to the occurrence of higher-density deformation twinning and microbands.