抄録
As for the alloying additions of carbon (C) and nitrogen (N), the involvement of solute hydrogen (H) in face-centered-cubic (FCC) Fe-Cr-Ni-based austenitic steels causes considerable magnitude of solid solution-hardening. Notably, the strengthening ability of these three interstitial elements is almost comparable to each other, although H is significantly smaller than C and N in its atomic size. The present paper overviews the phenomenology of such H-induced solid solution-hardening and its underlying rationales in commercial 300-series Fe-Cr-Ni austenitic steels after uniform H-charging in pressurized gaseous H2 environment at elevated temperatures. The effects of H concentration, deformation temperature, strain rate, and chemical composition of the alloy, as well as the thermal activation process of deformation, are extensively reviewed based mainly on the authors’ recent works. Potential roles of three key factors: 1) solute drag of H atmosphere around a dislocation; 2) H-diffusion-controlled glide of dislocation core; and 3) the presence of H-substitutional complex, are discussed in light of the conventionally established theories of dislocation dynamics and plasticity. The H-induced solid solution-hardening is maximized when the factors 1) and 2) (i.e., dynamic interactions between diffusible H and mobile dislocation) exert primary contributions to the flow stress. This fact is attributed to the exclusively high mobility of H atoms in austenite lattice even at around an ambient temperature, which is not the case for C and N that remain immobile during the deformation.
