Mechanical Behaviour of candidate steels in LBE after irradiation in BR2 at 200°C

High Chromium ferritic/martensitic (F/M) steels are presently considered among the most promising candidates as structural materials for the window of the spallation target MEGAPIE, on account of the severe expected service conditions, namely significant hardening and embrittlement caused by both neutron irradiation and production of spallation elements. This paper contains the results on basic in-service properties of three conventional 9-12Cr F/M steels: 9Cr1Mo (EM10), 9Cr1MoVNb or Mod. 9Cr1Mo (T91) and 12Cr1MoVW (HT9) after Neutron Irradiations followed by Post Irradiation Examinations (PIE). The investigation consists in the irradiation at 200 °C up to 2.6 and 4.3 dpa of tensile, KLST (miniature Charpy) and precracked KLST specimens, which have been subsequently tested in order to assess the post-irradiation mechanical properties. In addition and in order to assess the effect of the liquid metal, irradiated tensile samples were tested under controled atmosphere (air) and in liquid LBE. Under these conditions, none of the material was susceptible to liquid metal embrittlement. The observed hardening and embrittlement are due to irradiation solely