Mechanical properties and microstructures in F82H steel irradiated under alternating temperature

Reduced-activation martensitic steel F82H was irradiated at alternating temperatures between 230 and 350 °C to the accumulated damage level of 1.5 dpa using an irradiation capsule with temperature control independent of reactor power. Tensile tests were conducted in order to investigate the effects of the irradiation temperature variations on mechanical properties of F82H. Electron microscope observations were performed for the irradiated F82H to evaluate microstructural evolution of the specimens following varying temperature irradiation. Yield stress of the F82H irradiated at 50% alternating temperature between 230 and 350 °C was relatively large compared with the other temperature variations in this study. Size and number densities of dislocation loops were observed to be affected by changing irradiation temperature. The distinctive hardening behavior could be interpreted by the difference in the size and density of the defect clusters in terms of the effect of varying temperature.