Neutron damage of austenitic stainless steels as candidate materials of blanket-components in a fusion reactor

Abstract

Base materials of type 316 and Ti-modified austenitic steel (JPCA) and weld-joints of these materials were irradiated in HFIR at 55 °C to fluences up to 1.12×10 27 neutrons/m 2 (> 0.1 MeV), which produced up to 56 dpa and 3630 appm He. Tensile tests at room temperature showed a large increase in strength properties and that the weld-joints are weaker than the base-materials. The ductility of all materials was reduced by irradiation. For the irradiated weld-joint, deformation and fracture occurred mainly in part of the weldment. This data shows that the benefit of a cold-worked material (which is high strength) could no longer be expected in the weld-joint. The increase in strength and work-hardening rate by MC-precipitates, with the addition of Ti and Nb to the filter metal, is necessary to improve the deformation behavior of the irradiated weld-joints in type 316 stainless steel and JPCA.