On hydrogen-induced shear localization in austenitic steels triggered by dislocation interactions with short-range order

We investigate the interaction of short-range order (SRO) with dislocations as mechanism underlying hydrogen-induced plastic flow localization in austenitic stainless steels. Our approach is motivated by the fact that short-range order is known to advance glide plane softening and that classic metrics of embrittlement such as hydrogen induced reduction of the stacking fault energy and the formation of α’ martensite are neither necessary nor sufficient conditions for failure of austenitic systems by hydrogen enhanced localized plasticity. We show that the presence of a microscale band whose mechanical response is governed by the formation of a dislocation pileup against an SRO nanodomain in a specimen strained homogenously can lead to the onset of plastic flow localization at the macroscale when the pileup breaks through the SRO’s stress field. This link between hydrogen-induced plastic flow localization and material failure at the macroscale underpinned by dislocation interactions with short-range ordering at the microscale holds promise toward the design of austenitic microstructures with compositions tailored to suppress such flow localization.