We investigated the effects of hydrogen on ε-martensite-related damage evolution (crack/void initiation and growth) in Fe-Mn-Si-base austenitic steel using tensile tests after gaseous hydrogen charging at 100 MPa. Specifically, we evaluated the quantitative hydrogen effects on ε-martensite fraction and associated damage evolution with different strains and strain rates. Hydrogen charging increased the probability of ε-martensite-related damage initiation and deteriorated micro-damage arrestability, which decreased elongation. The primary factor causing the detrimental hydrogen effects on resistance to damage evolution was the promotion of deformation-induced γ-ε martensitic transformation. An increasing strain rate from 10−4 to 10−2 s−1 suppressed the γ-ε martensitic transformation and correspondingly increased elongation. Interestingly, the ε-martensite fraction near the fracture surface did not change with increasing strain rate, but the area fraction of the brittle-like fracture region decreased. This fact implied that the brittle-like fracture at the low strain rate, which had a longer time for damage growth, was assisted by stress-driven hydrogen diffusion near the crack/void tips.
|Number of pages||11|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|Publication status||Published - 2020 Dec|