A Physical-Mechanical Model of Ductile Fracture in Irradiated Austenitic Steels

We present the equations that describe nucleation and growth of voids in austenitic steels during deformation under various stress-state triaxiality ratios. The authors put forward a criterion of fracture due to void merging through the plastic instability mechanism in a void-containing material or through the channel mechanism, i.e., shearing of bridges between voids. The equations include two void populations – the deformation-caused voids and the vacancy voids that arise during irradiation and result in the irradiation-induced swelling. The authors perform modeling of the influence of various factors (test temperature, neutron irradiation dose, stress-state triaxiality, irradiation-induced swelling) on plasticity and fracture toughness of material. The calculated results are compared to experimental findings. The influence of the stress-state triaxiality on plasticity of an irradiated material has been clarified. A relation has been found between the strain hardening parameters and plasticity, fracture toughness of material.