Physical and mechanical modeling of the neutron irradiation effect on ductile fracture. Part 2. Prediction of swelling effect on drastic decrease in strength

Abstract A drastic decrease in the ultimate tensile strength of irradiated austenitic steels with high swelling values is considered. The physical–mechanical model proposed in Part 1 of the present paper is applied for the prediction of a drastic decrease in ultimate tensile strength. The mechanism called by the authors the “running collapse mechanism” is used for modeling the material ductile fracture when stresses are less than the yield strength. This ductile mechanism is similar to brittle fracture when crack propagates unstable manner. Running collapse mechanism occurs due to evolution of vacancy voids resulting in irradiation swelling. Nanoscale of vacancy voids (void sizes, distance between voids) results in the possibility of ductile fracture in very small zones whose size is considerably smaller than the grain size.