Physical and mechanical modeling and prediction of fracture strain and fracture toughness of irradiated austenitic steels

• Ductile fracture model based on voids nucleation, growth and coalescence is proposed.
• The model takes into account swelling, radiation hardening and stress triaxiality.
• It predicts a fracture strain and fracture toughness of irradiated austenitic steels.
• The model predicts a drastic decrease of these parameters due to radiation swelling.
• Results of prediction by the model are in good agreement with experimental data.

A physical-and-mechanical model of ductile fracture has been developed to predict fracture toughness and fracture strain of irradiated austenitic stainless steels taking into account stress-state triaxiality and radiation swelling. The model is based on criterion of plastic collapse of a material unit cell and takes into account deformation voids nucleation, growth of deformation and vacancy voids, and their coalescence controlled by strain hardening of a material.For justification of the model experimental data on fracture strain and fracture toughness of austenitic stainless steel 18Cr–10Ni–Ti grade irradiated up to 46–49 dpa with various swelling were used. Experimental data on fracture strain and fracture toughness are compared with the results predicted by the model. It has been shown that for prediction of the swelling effect on fracture toughness the dependence of process zone size on swelling should be taken into account.