Crystallization of CaO-SiO2-TiO2 slag as a candidate for fluorine free mold flux

Abstract

The time-temperature-transformation diagram (TTT diagram) of CaO-SiO 2-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 CaOSiO 2TiO2 in CaO-SiO2-TiO2 slag is as small as that of cuspidine (3CaO2SiO2CaF2) in commercial mold fluxes. This finding indicates that the CaOSiO 2TiO2 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-SiO 2-TiO2 slag is substituted for cuspidine in commercial mold fluxes. The thickness of the crystalline layer of CaOSiO 2TiO2 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 CaOSiO2TiO 2 at high temperature. © 2006 ISIJ.