Mechanical response of oxide dispersion strengthened (ODS) EUROFER97 after neutron irradiation at 300 deg. C

EUROFER97 is a 9Cr-1W-0.2V-0.1Ta reduced activation ferritic/martensitic (RAFM) steel, presently considered within the European Union as the primary candidate structural material in a fusion power plant. Its mechanical strength properties currently prevent its use at temperatures higher than 500-550 deg. C. In an effort to extend the range of operating temperatures to 600-650 deg. C and therefore enhance the efficiency of the machine, a different production route, oxide dispersion strengthening (ODS), is being investigated. The characteristics of different versions of EUROFER97 ODS have been assessed in recent years, leading to the improvement of the material by a combination of optimized production process and post-HIPping thermal treatment. Until recently, the mechanical properties of EUROFER97 ODS had only been investigated in the unirradiated condition, and no information was available for the irradiation response of the material. However, mechanical samples have been irradiated during 2004-2005 at 300 deg. C in the Belgian Reactor 2 (BR2) in Mol up to an accumulated dose of 1.73 ± 0.07 dpa; post-irradiation tensile, Charpy impact and fracture toughness tests have been performed in the hot cell laboratories of the Belgian Nuclear Centre (SCK-CEN). The results obtained allow quantitatively assessing the degradation of mechanical properties induced by neutron irradiation. Comparisons are also presented with similar results obtained from base (non-ODS) EUROFER97, previously irradiated in BR2 under comparable conditions (temperature and dose)