Irradiation Stability of PM-HIP Steels for Heavy Nuclear Components

This talk will highlight unique irradiation responses of steels manufactured by powder metallurgy with hot isostatic pressing (PM-HIP) for heavy nuclear structural components. Austenitic and ferritic stainless steels are structural alloys for current and future nuclear reactors. The industry has growing interest in replacing steel castings and forgings with PM-HIP components, but the irradiation performance of PM-HIP steels must first be understood. Here we will present several unusual characteristics of irradiated PM-HIP steels attributed to their synthesis. In low-alloy ferritic steels, residual precipitation from PM-HIP processing can compromise the as-fabricated ductility. But on the other hand, precipitate-matrix interfaces are strong sinks for irradiation-induced defects, which may limit irradiation hardening and embrittlement. In higher-alloyed ferritic steels, accelerated pipe diffusion of Si along dislocation lines creates unexpected irradiation-induced softening. Finally, in PM-HIP austenitic 316L stainless steel, irradiation induces pseudoelastic tendencies. Collectively, these results reveal exceptional resilience of PM-HIP steels to extreme irradiation environments.