Dose-dependent irradiation hardening and elevated-temperature creep degradation in oxide dispersion-strengthened steels

Oxide dispersion strengthened (ODS) steels have emerged as preferred materials for critical components in next-gen nuclear systems, owing to their exceptional high-temperature stability, radiation damage tolerance, and enhanced mechanical performance under extreme operational conditions. However, the quantitative relationship between irradiation conditions (temperature and dose) and mechanical properties remains unclear, limiting their industrial deployment. This research develops a constitutive crystal plasticity framework combining void-oxide dispersion characteristics to mechanistically evaluate irradiation-induced hardening and creep responses in the irradiated ODS steels. The model demonstrates excellent agreement with experimental data across varying temperatures and irradiation doses. In contrast to the traditional model of void hardening, the current model exhibits far superior agreement with experimental measurements. The yield stress of irradiated ODS steels exhibits a non-monotonic dependence on irradiation dose, initially increasing to a peak value before decreasing with further dose accumulation. Consequently, the void hardening effect strengthens before eventually tapering off. Conversely, the yield strength diminishes with a rising irradiation temperature due to an expanded void spacing associated with high temperature. Under irradiation, ODS steels demonstrate a non-monotonic creep response: strain rate firstly declines then amplifies with escalating dose, while exhibiting a continuous thermal acceleration trend at higher temperatures. Slightly high irradiation doses cause large voids without significantly expanding void spacing, thus enhancing dislocation obstruction. This work provides a highly effective theoretical approach for accurately assessing the irradiation performance of ODS steels under complex environments.