Tensile properties of candidate SNS target container materials after proton and neutron irradiation in the LANSCE accelerator

Tensile specimens of five austenitic stainless steels and two ferritic/martensitic (f/m) steels were irradiated under spallation conditions at temperatures between 60°C and 164°C to doses between 0.4 and 11 dpa. The irradiations were performed at the Los Alamos Neutron Science Center (LANSCE) accelerator in a beam of 800 MeV protons and in the mixed spectrum of protons and spallation neutrons from a tungsten target. Tensile testing was done at room temperature at a crosshead speed of 0.005 mm/s, corresponding to a strain rate of 10−3 s−1. All materials showed considerable irradiation hardening and loss of ductility. For EC316 LN stainless steel, which is the recommended material for construction of the spallation neutron source (SNS) mercury target container and shroud, the yield strength (0.2% offset) was increased by a factor of three at 11 dpa. This steel retained a significant uniform elongation of 6%, as did the other austenitic steels. The two f/m steels entered plastic instability failures at strains less than 1% for all doses.