Abstract: A mold flux is used in continuous casting of Ti-containing hypo-peritectic steel so as to prevent longitudinal cracks from forming on a surface of a slab. The mold flux contains CaO, SiO2, an alkali metal oxide and a fluorine compound as major components. f(1), f(2) and f(3), which are calculated from the initial chemical composition, are (1.1?0.5×T) to (1.9?0.5×T), 0.05 to 0.40 and 0 to 0.40, respectively, if the Ti content of the molten steel (mass %) is T. The TiO2 content in the melting state during the casting is no more than 20 mass % and the ratio of the first peak height of perovskite to the first peak height of cuspidine in the mold flux film is no more than 1.0.

Abstract: A mold flux is used in continuous casting of Ti-containing hypo-peritectic steel so as to prevent longitudinal cracks from forming on a surface of a slab. The mold flux contains CaO, SiO2, an alkali metal oxide and a fluorine compound as major components. f(1), f(2) and f(3), which are calculated from the initial chemical composition, are (1.1?0.5×T) to (1.9?0.5×T), 0.05 to 0.40 and 0 to 0.40, respectively, if the Ti content of the molten steel (mass %) is T. The TiO2 content in the melting state during the casting is no more than 20 mass % and the ratio of the first peak height of perovskite to the first peak height of cuspidine in the mold flux film is no more than 1.0.