抄録
A constitutive equation of irradiation creep for irradiated materials applicable to structural analyses in a multiaxial state of stress was developed. After reviewing microscopic mechanisms of irradiation creep and swelling, the relevant theories proposed from the view point of metallurgical physics and their applicability were discussed first. Then a constitutive model was developed by assuming that irradiation creep can be decomposed into irradiation-enhanced creep and irradiation-induced creep. By taking account of the SIPA (Stress Induced Preferential Absorption) mechanism, the irradiation-induced creep was represented by an isotropic tensor function of order one and zero with respect to stress, which is, at the same time, the function of neutron flux and neutron fluence. The volumetric part of the irradiation-induced creep was identified with swelling. The irradiation-enhanced creep was described by modifying Kachanov-Rabotnov creep damage theory by incorporating the effect of irradiation. Finally the irradiation creep and swelling of type 316 stainless steel at elevated temperatures were predicted by the proposed constitutive equation, and the numerical results were compared with the corresponding experimental results.
