Effect of neutron irradiation to 0.7 and 1.4 dpa on the tensile mechanical properties and microstructure of EUROFER97 steel

Several grades of reduced-activation ferritic-martensitic (RAFM) steels have been proposed for fusion applications (e.g., blanket first wall) since the 1990s all over the world. Four batches of the European reference RAFM steel EUROFER97 have been produced since 1998. The RCC-MRx design code, developed, among others, for fusion reactors, currently contains a provisional section dedicated to EUROFER97, encompassing properties of the first two batches, whereas minimum three batches are required for a full qualification and final inclusion of a material into RCC-MRx. The EUROfusion project coordinates efforts to broaden the knowledge of EUROFER97 properties relevant for fusion reactors ITER and DEMO, preparing them for closing the database gaps in RCC-MRx and aggregating them in the DEMO material property handbook (MPH). Its purpose is to provide average and minimum curves of required properties according to the DEMO engineering design and manufacturing needs. The present work reports mechanical properties and fractographic analysis of batch 4 of neutron-irradiated EUROFER97 for the first time. The measured strength and ductility are in line with the data already aggregated in the MPH. SEM investigation confirms that the dimple fracture is retained in the material after neutron irradiation up to 1.4 dpa in the temperature range 25…550 °C.