Abstract: An improper secondary cooling regime in slab continuous casting can lead to issues including slab bulging,slab stalling,mold level fluctuations,and even breakouts resulting from longitudinal cracking or slag entrapment.This paper has focused on the high casting speed continuous casting process of IF steel slabs at a domestic steel plant.A two-dimensional unsteady heat transfer model was developed and calibrated using results from nail shooting experiments.The solidification and heat transfer behavior of IF steel slabs under various water distribution patterns were analyzed,and an optimized cooling strategy was proposed.Calculation results indicate that when the water distribution scheme derived from the on-site thermal tracking model was applied in production trials,the solidification end point predicted by the two-dimensional unsteady model shifted further downstream with increasing casting speed compared to that predicted by the on-site model.This deviation is consistent with the intensified red-hot slab observed in practice,indicating an increased risk of slab bulging.Therefore,to meet both the temperature requirements in the straightening zone and the suitable position for the soft reduction process,it is recommended to increase the water flow in secondary cooling zones 5-8 by a factor of 1.25 while maintaining the original water flow in zones9-10 when the casting speed is increased.