Effect of tempering temperature and time on tensile properties of F82H irradiated by neutrons

The dependence of tensile properties on tempering time and temperature was examined for a martensitic steel F82H irradiated at 250 °C to a neutron dose of 1.9 dpa in the Japan Materials Testing Reactor. The specimens were first normalized at 1040 °C for 0.5 h and tempered at 750 °C for 1 h. A second heat treatment was performed at temperatures from 750 to 800 °C for 0.5 h after the normalizing at 1040 °C for 0.5 h. The second tempering time at 750 °C was varied from 0.5 to 10 h. The tensile specimens of F82H + 2Ni, pure iron and Fe + 0.1C were also irradiated. Tensile tests were carried out at room temperature. The radiation hardening of F82H was significantly relieved by the second heat treatment, and it was smaller than that of the first heat treated other steels. The radiation hardening depended on the tempering conditions and tended to increase with increasing the temperature and time of tempering.