A Mathematical Model to Predict Austenite Grain Size in Ti-Bearing Microalloyed Steels

摘要

A mathematical model is proposed to predict the mean austenite grain size during reheating of Ti-bearing microalloyed steels. The model is derived based on the Zener approach. Effects of heterogeneity in austenite grain sizes in the initial (prior to coarsening) microstructure and size and shape of the pinning particles on the critical grain radius (R_c) are incorporated in the proposed model. The model is then solved by utilizing the models developed earlier which calculate particle coarsening and dissolution to arrive at the mean austenite grain radius during reheating as a function of reheating temperature and time. It is shown that the predicted austenite grain radius compares reasonably well with the experimental grain growth data for Ti-bearing microalloyed steels in as-cast slab as well as in controlled rolled plate conditions.