The 11 MeV proton irradiation behavior of ferritic steels

Depth profiles of micro-Vickers hardness, X-ray diffraction line-width and internal magtnetic field were measured on SUS410L steel and pure iron after irradiations with 11 MeV protons at ∝800 K and ∝400 K. The increases of hardness, diffraction line-width and internal magnetic field after the low temperature irradiation were similar to that after the high temperature irradiation. In the case of pure iron only a hardness increase was observed, and the increase is also similar to the hardness increase on the SUS410L steel. The temperature dependence of fracture energy derived from small punch tests provided an information on the ductile-brittle transition temperature (DBTT) of HT-9 steel by using the statistical analyses. Proton irradiation did not result in a considerable shift of the DBTT. The origin of hardness increase by the proton irradiation may be the irradiation-induced defect. Proton irradiation did not cause a severe embrittlement on HT-9 steel. Depletion of Cr from the matrix seems to be enhanced by the proton irradiation. (orig.)