GRAIN-GROWTH PREDICTIONS IN MICROALLOYED STEELS

Empirical models for grain growth predictions are briefly reviewed. It is demonstrated that such models are inadequate for quantitative pred iction of austenite grain growth during reheating of as-cast microstru ctures in microalloyed steels. This inadequacy is mainly attributable to the inability of empirical models to account for abnormal grain gro wth. Basic principles of grain growth are therefore revisited in an at tempt to develop a mathematical model which can account for abnormal g rain growth. Such a model has been developed for Ti:N balanced microal loyed steels and is presented here. It is shown that quantitative pred ictions of austenite grain growth generated from this model fit well w ith experimental grain growth data obtained during reheating of as-cas t slabs of Ti, Ti + Nb as well as Ti + Nb + Mo containing microalloyed steels.