| Abstract Scope |
This study investigates the influence of neutron irradiation on the mechanical properties of austenitic and ferritic stainless steels, with a comparative focus on conventionally processed and additively manufactured (AM) stainless steels, as well as various ferritic-martensitic (FM) and oxide dispersion-strengthened (ODS) ferritic steels. Austenitic steels, which initially exhibit high ductility, generally reached their relatively low fracture stresses at higher irradiation doses, whereas the less ductile ODS ferritic and FM steels reached their relatively high fracture stresses at lower doses. Strengthening within each group—through AM processing in austenitic steels and oxide particle dispersion in ferritic steels—significantly shortened the irradiation life to embrittlement, as the true fracture stress remained nearly unchanged at low doses or declined due to irradiation-induced degradation. In particular, AM 316L exhibited a fine, metastable microstructure with initially high strength but reduced ductility compared to its conventionally processed counterpart. It showed relatively less hardening and ductility loss during low-temperature irradiation, suggesting convergence in mechanical behavior with the wrought 316L variant. FM and ODS steels, though generally expected to exhibit strong radiation tolerance and thermal stability, showed a significant decrease in fracture toughness above 600 °C, with some ODS steels displaying pronounced thermal embrittlement. Fracture toughness–yield strength analysis revealed an inverse correlation, highlighting differences in deformation mechanisms while showing consistent trends across alloy groups. These findings underscore both the distinct irradiation responses and shared mechanical behaviors of austenitic and ferritic steels, offering critical insights for the selection of structural materials in nuclear reactor environments. |