Crystallization of CaO–SiO₂–TiO₂ Slag as a Candidate for Fluorine Free Mold Flux

Abstract

The time-temperature-transformation diagram (TTT diagram) of CaO–SiO₂–TiO₂ slag has been determined by using differential thermal analysis (DTA) in order to investigate the crystallization of the slag as a candidate for fluorine free mold flux. The incubation time of CaOSiO₂TiO₂ in CaO–SiO₂–TiO₂ slag is as small as that of cuspidine (3CaO₂SiO₂CaF₂) in commercial mold fluxes. This finding indicates that the CaOSiO₂TiO₂ crystallizes rapidly in the slag film between the mold and the steel in the continuous casting machine, similar to cuspidine in commercial mold fluxes. CaOSiO₂TiO₂ in CaO–SiO₂–TiO₂ slag is substituted for cuspidine in commercial mold fluxes. The thickness of the crystalline layer of CaOSiO₂TiO₂ is smaller than that of cuspidine. In order to improve the heat transfer control of CaO–SiO₂–TiO₂ slag, it is necessary to decrease the incubation time of CaOSiO₂TiO₂ at high temperature.