Short-range order influences H distribution in Fe–Ni–Cr austenitic stainless steels

Hydrogen embrittlement (HE) in austenitic stainless steels is advanced by hydrogen-enhanced localized plasticity (HELP), typically accompanied by a transition from homogeneous to localized slip. Short-range order (SRO) in face-centered cubic (FCC) alloys promotes slip planarity, and recent studies suggest that H may amplify this localization. However, the interplay between H and SRO remains unclear. Here, we employ a spin cluster expansion model combined with Monte Carlo simulations to study this interplay in Fe-Ni-Cr alloys. Chemical order is quantified using Warren-Cowley SRO parameters, and the model is validated against experimental data. We find that H only slightly alters the intrinsic ordering preference of the alloys. As temperature decreases, H-Ni and H-Cr pairs exhibit stronger ordering tendencies than H-Fe pairs, indicating a selective affinity of H for certain atomic environments. Furthermore, pre-existing SRO significantly affects H distribution by promoting local H enrichment in SRO domains. Such SRO-driven local H accumulation may facilitate slip localization and contribute to the early onset of embrittlement. These findings provide thermodynamic and structural insights into H-SRO interactions, with implications for how HELP and SRO bring about HE in austenitic stainless steels.