Fracture properties and mechanisms for irradiated austenitic steels over high temperature range and formulation of fracture criterion. Part 2. Fracture criterion and model

On the basis of experimental data considered in the first part of the paper the fracture criterion and fracture model are represented for high temperature radiation embrittlement of irradiated austenitic steels. The proposed model allows one to explain larger value of the fracture strain for notched cylindrical specimens as compared with smooth specimens as it has been found in the first part of the paper and also to predict fracture toughness over range of high temperature radiation embrittlement. The formulated criterion and model are verified by comparison of the calculated and experimental values of fracture toughness for 18Cr-9Ni steel irradiated up to damage dose of (24–30) dpa. Experimental values of fracture toughness are obtained from compact tension CT-0.5 specimens tested at 200°С and 600°С. The fracture toughness data for irradiated steel are represented also over temperature range from 20°С and 600°С.