TENSILE PROPERTIES OF NEUTRON-IRRADIATED 9CR-WVTA STEELS

Tensile properties of the reduced activation martensitic steels 9Cr-1WVTa and 9Cr-3WVTa were investigated over the range from room temperature to 873 K after irradiation in the Japan Materials Testing Reactor at about 538 K. Modified 9Cr-1MoVNb steel was also examined for comparison. The increase in yield stress due to irradiation measured at room temperature was smaller in the 9Cr-1WVTa and 9Cr-3WVTa steels than in conventional 9CT-1MoVNb steel and was smaller in the low-W steel than in the high-W steel. With increasing test temperature, the irradiation hardening exhibited a further increase at around 573 K and then decreased to zero over the range from 673 to 873 K. The increase in irradiation hardening at around 573 K was believed to be due to vacancy-carbon complexes. The present results were also compared with earlier irradiation hardening experiments.