DEFORMATION AND FRACTURE IN IRRADIATED AUSTENITIC STAINLESS-STEELS

Irradiation of austenitic stainless steels to about 10 dpa at about 300-degrees-C results in yield stress levels of up to 1000 MPa and severe reductions in uniform engineering strains to below 1%. Toughness is also degraded as the fracture mechanism evolves from microvoid coalescence in the unirradiated condition to highly localized deformation in a decohesion zone in the severely irradiation embrittled state. Current toughness models are inadequate and better understanding of the micromechanics and macromechanics of deformation and fracture is needed to reliably predict failure criteria for fusion structures. While irradiated welds appear to have the least favorable combination of strength and ductility, cold-worked steels appear to show less mechanical degradation than solution annealed alloys.