Effect of neutron irradiation on the microstructure of modified SUS316 stainless steels

The microstructures of heavily neutron-irradiated specimens of compositionally-modified SUS316 stainless steel of were carefully studied and characterized by transmission electron microscopy (TEM) to establish the onset mechanism of radiation-induced swelling and to characterize the effects of neutron irradiation on the microstructures. Materials with remarkably high swelling were included. It is demonstrated that the microstructural evolution, including the radiation-induced swelling, depends strongly on the irradiation conditions. The relationship between the onset of swelling and microstructural evolution is complex while the effect of irradiation temperature are relatively large. The mechanisms controlling the onset of swelling at a specific temperature or temperature range are discussed based on the microstructures.