CRACK GROWTH RATES AND FRACTURE TOUGHNESS OF NEUTRON IRRADIATED GRAIN- BOUNDARY-ENGINEERED AUSTENITIC STAINLESS STEELS

摘要

Reactor internal components made of austenitic stainless steels (SSs) are susceptible to irradiation-assisted stress corrosion cracking (IASCC) after prolonged exposure to neutron irradiation. It has been shown in many nonirradiated materials that coincident site lattice (CSL) grain boundaries with low-Z value are more resistant to intergranular cracking. Grain-boundary-engineering (GBE) treatment, that increases low-E CSL boundaries, is thus suggested to be a potential mitigation method for IASCC. In this study, the effect of GBE treatment on IASCC susceptibility is evaluated. Crack growth rates of neutron irradiated GBE SSs are measured in simulated boiling water reactor environment. Cracking behavior is analyzed for Type 304 and 316 SSs at ~2 dpa with and without GBE treatment. Fracture toughness data is also obtained for these alloys to assess the effect of the GBE treatment on radiation embrittlement.