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

The microstructures, prior and posterior to volumetrically remarkable swelling, of heavily neutron-irradiated specimens of compositionally-modified SUS316 based steel were carefully studied and characterized by using transmission electron microscope(TEM) and high resolution TEM to make clear an onset mechanism of radiation-induced swelling as well as an effect of neutron irradiation on microstructure. As the results of TEM study, it was demonstrated that the microstructural evolutions, including radiation-induced swelling, depended strongly on the irradiation condition. The relationship between the onset of swelling and microstructural evolution is quite complicated but the effects of irradiation temperature on microstructural changes appear to be relatively large. The onset mechanisms of swelling at a specific temperature or temperature range are discussed from the viewpoint of microstructure in this paper.