Calculation of radiation-induced deformation of SUS 316 in the ITER-relevant condition

SUS 316 stainless steel will be used in ITER as a major structural material. However, accumulation of radiation-induced deformation data in the anticipated operation temperature range, centered at about 300 deg. C, is not adequate. Although it will be used mainly in annealed condition, cold-working and consequent introduction of network dislocations is inevitable at various parts of the structure. Computer simulation was performed to examine the radiation-induced deformation of SUS 316 steel, with emphasis on the effect of network dislocation density, for the ITER-relevant condition. Irradiation creep rates and radiation-induced stress relaxation behaviors were examined at 300 deg. C for various displacement rates, applied stresses and network dislocation densities. Rather complicated dependence on dislocation density has been predicted in both creep deformation and stress relaxation. This complexity results from a competitive redistribution of point defects to the operating deformation mechanisms and from the predominance among them that depends on the network dislocation density