Method of continuous casting of sub-peritectic steel containing Ti using flux for mold

摘要

A method of continuous casting of hypo-peritectic steel containing Ti, the method comprising: the continuous casting of hypo-peritectic steel containing 0.1% to 1% by mass of Ti using a mold flux, wherein the flux of mold contains CaO, SiO2, an alkali metal oxide and a fluorine compound as main components, wherein each main component has a content of not less than 5% by mass and the total content thereof is not less than 70% by weight. mass, the chemical composition of the mold flux before its introduction into the mold satisfies formulas (1), (2) and (3), a TiO2 content of the mold flux in a molten state during casting is not greater than 20% by mass and a ratio of intensities of a film of the mold flux in the solidification state after casting is not greater than 1.0: ** Formula ** where, in the formulas (1) to (3) ): f (1) = (CaO) h / (SiO2) h ... (A) f (2) = (CaF2) h / {(CaO) h + (SiO2) h + (CaF2) h} ... (B) f (3) = {(alkali metal fluoride) h} / {(CaO) h + (SiO2) h + (alkali metal fluoride) h)} ... (C), where, in the formulas (A) to (C): (CaO) h = WCaO - (CaF2) hx 0.718 ... (D) (SiO2) h = WSiO2 ... (E) (CaF2) h = ( WF - WLi2O x 1.27 - WNa2O x 0.613 - WK2O x 0.403) x 2.05 ... (F) (alkali metal fluoride) h = WLi2O x 1.74 + WNa2O x 1.35 + WK2O x 1, 23 ... (G) where T is a Ti content of the molten steel (mass%), WCaO is a CaO content of the mold flux (mass%), WSiO2 is a SiO2 content of the mold flux (% by mass), WF is an F content of the mold flux (mass%) and WLi2O, WNa2O and WK2O are the contents of Li2O, Na2O and K2O, respectively, which are alkali metal oxides, of the mold flux (% by mass), and where the ratio of film intensities refers to a ratio between a height of the first peak of perovskite and a height of the first peak of cuspidin, where the ratio is obtained from the analysis of di X-ray fraction of the powders obtained by spraying the film of the mold flux.