Tensile properties and transition behaviour of RAFM steel plate and welds irradiated up to 10 dpa at 300 °C

Reduced activation ferritic/martensitic (RAFM) steels have been irradiated in a large irradiation campaign in the high flux reactor at a target temperature of 300 °C up to target dose levels of 2.5, 5, and 10 dpa. Tensile and impact properties have been determined of RAFM plate, tungsten inert gas (TIG) welds and Electron beam (EB) welds. The dose level dependence of both properties is evaluated. In addition, impact properties of F82H powder hot isostatic pressing after 2.5 dpa and transition fracture toughness of F82H-mod. plate after 5 dpa have been measured. The tensile properties at irradiation temperature of F82H-mod. plate and welds show an increase in yield and ultimate strength up to about 5 dpa, after which saturation seems to set in. The elongation data show evidence of increasing localisation of deformation at higher doses. Impact properties of untempered EB welds and not sufficiently tempered NF616 show the need for good tempering treatment. Impact properties of various zones of irradiated TIG welds further illustrate the influence of the microstructural state of 8–9Cr steels on the irradiation response.