Origin of hardening and deformation mechanisms in irradiated 316 LN austenitic stainless steel

The effects of displacement damage and trapped helium on deformation microstructures in AISI 316 LN austenitic stainless steel were studied by applying a newly developed disk bend method to specimens irradiated with 360 keV He ions at 200°C. Radiation damage microstructures consisted of an intimate mix of black dots, dislocation loops, and very small helium filled cavities. In the unirradiated specimens, the deformation mode upon straining was planar glide with cross-slip. With increasing dose, cross-slip was progressively restricted. Correspondingly, deformation microstructure changed from dislocation network dominant to channeling dominant. The channel bands were composed of piled-up dislocations, stacking faults, and twinned layers.