Post-irradiation mechanical properties of three EUROFER97 joints

Within the development of reduced activation ferritic martensitic (RAFM) steels as prominent structural materials for future fusion reactors, EUROFER97 has recently emerged in Europe as the reference material for the DEMO design. In order to characterise the in-service performance of EUROFER97 as structural material, it is important to assess the properties of welded joints, particularly under irradiation. In the present paper, three EUROFER97 joints (two diffusion welds and one TIG weld) have been irradiated in the BR2 reactor of SCK-CEN at 300 ◦C up to 1.8 dpa and subsequently characterised for tensile, impact and fracture toughness properties. Comparisons of the results are provided with base EUROFER97 (both unirradiated and irradiated under similar conditions) and, where available, with properties measured on the joints in the unirradiated condition. The post-irradiation mechanical behaviour of both diffusion joints (“laboratory” and “mock-up”) appears similar to that of the base material; therefore, diffusion joining looks a very promising technique. On the other hand, the properties of the TIG joint are affected by the lack of a post-weld heat treatment, which causes the material from the upper part of the weld to be significantly worse than that of the lower region.