Grain growth kinetics model of high-temperature ferrite and austenite in Ti microalloyed steel during continuous casting

• A two-stage austenite growth model incorporating second-phase pinning and δ–γ transformation accurately predicts grain sizes in Ti microalloyed steel slabs, with average error within 5%. • Increasing Ti content from 0.02wt% to 0.04wt% significantly refines austenite grains, especially at the slab center, achieving a 27.14% average reduction. • High-temperature ferrite growth follows parabolic kinetics, but higher Ti content slows grain boundary migration during initial solidification. • The model provides a robust tool for optimizing continuous casting parameters to enhance slab quality and reduce crack defects.