Previous models for grain growth are usually based on Beck's formula, which are inadequate for quantitative prediction of austenite grain growth during reheating of as cast microstructures in microalloyed steels. The applications of these empirical grain growth models are limited to some particular categories of steels, such as Nb, Nb-Ti and Ti-V microalloyed steels, etc. In this study, a metallurgically based model has been developed to predict the austenite grain growth kinetics in microalloyed steels. This model accounts for the pinning force of second phase particles on grain boundary migration, in which the mean particle size with time and temperature is calculated on the basis of the Lifshitz-Slyozov-Wagner (LSW) particle coarsening theory. The volume fraction of precipitates is obtained according to the thermodynamic model. The reliability of the model is validated by the agreement between theoretical predictions and experimental measurements in the literature. List of symbolsC solute content dissolved in matrix D diffusion coefficient D c austenite grain size D c0 initial austenite grain size f volume fraction of particles M grain boundary mobility n grain growth exponent P Z Zener pinning force r mean particle radius r 0 initial particle radius R universal gas constant R c austenite grain radius R c0 initial austenite grain radius t time T temperature V molar volume of particle a adjustable parameter d grain boundary thickness s interfacial energy

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