Factors affecting prior austenite grain size in low alloy steel

The effect of varying normalising and hardening temperatures on the prior austenite grain size in a low alloy Cr-Mo-Ni-V steel has been examined. An initial relative insensitivity of grain size to increasing austenitising temperature was observed followed by a sudden growth of grains at approximately 1000 degrees C. A detailed study of the precipitates in the steel showed the presence of a bimodal size distribution of vanadium carbides. The grain size increase is attributed to a decrease in volume fraction and an increase in size of V4C3 particles with increasing temperature.