200-keV carbon ion irradiation of austenitic stainless steels

Austenitic stainless steels, types 304, 316 and 321, were irradiated by 200-keV C+ ions at 7000C and the irradiation induced voids were examined by transmission electron microscopy. Prior to C+ ion irradiation, He+ ions were injected. He+ ion dose dependence on void formation was studied systematically below 1.9x1016 He+/cm2. It was revealed that swelling increased linearly with helium dose. Only the He+ ion-injected and annealed specimen had many gas bubbles and they grew into voids due to successive C+ ion irradiation. The swelling in type 304 steel increased with dpa. The rate of increase in swelling is large in high dose. No trend of saturation was shown up to 85 dpa. (auth.)