High dose, up to 80 dpa, mechanical properties of Eurofer 97

In blankets of a fusion power plant 14 MeV neutrons produce displacement damage, dpa, and helium and hydrogen. Martensitic steels offer the advantages of low swelling and reduced helium embrittlement compared to austenitic steels. Reduced activation Eurofer 97 steel has been exposed to neutron displacement damage up to about 15 dpa in materials test reactors such as OSIRIS and HFR at temperatures in the range of RT to 600 degrees C, and up to 80 dpa in BOR-60 at temperatures in the range of 300-330 degrees C. The postirradiation mechanical properties in the range of 300-330 degrees C show increases in yield stress, decrease in ductility and an increasing ductile to brittle transition temperature. The hardening rate is decreasing with increasing damage level, but it does not show saturation at doses examined. Analyzing the present results and reviewing properties of other steels with different compositions, including ODS steels, lead to the conclusion that improvement of the radiation resistance of steel will be based on nano-microstructural features. (C) 2009 Published by Elsevier B.V.