HEAT-TREATMENT EFFECT ON IMPACT PROPERTIES OF REDUCED-ACTIVATION STEELS

The effect of heat treatment on the impact behavior of eight experimental heats of reduced-activation ferritic steels was investigated. Steels with 2 1/4, 5, 9, and 12 wt% Cr and containing tungsten, vanadium, and tantalum were examined. Impact properties of steels with 2 1/4 wt% Cr depended on microstructure, which was affected by cooling rate after austenitization. By heat-treating the 2 1/4 wt% Cr steels to change the microstructure from a bainitic structure containing ferrite to one without ferrite, the ductile-brittle transition temperatures were reduced substantially. The cooling rate had essentially no effect on the high-chromium martensitic steels.