Comparison of radiation-induced segregation in ultrafine-grained and conventional 316 austenitic stainless steels.

Due to a high number density of grain boundaries acting as point defect sinks, ultrafine-grained materials are expected to be more resistant to irradiation damage. In this context, ultrafine-grained 316 austenitic stainless steel samples have been fabricated by high pressure torsion. Their behavior under ion irradiation has been studied using atom probe tomography. Results are compared with those obtained in an ion irradiated conventional coarse-grained steel. The comparison shows that the effects of irradiation are limited and that intragranular and intergranular features are smaller in the ultrafine-grained alloy. Using cluster dynamic modeling, results are interpreted by a higher annihilation of point defects at grain boundaries in the ultrafine-grained steel.