Solidification Properties of CaO-SiO2-TiO2 Based Mold Fluxes

In continuous casting of peritectic steel grades sensitive to longitudinal cracking, the solidification properties of mold fluxes play an important role in keeping smooth running of continuous casting process and achieving high surface quality of casting strands. To reduce fluorine pollution in molten slag, types of CaO-SiO2-TiO2(CTS) based mold fluxes were investigated. The solidification and crystallization properties, including viscosity eta at 1 573 K, break temperature T-br, crystallization ratio R-e and solidification mineragraphy were measured, which were compared with those of CaO-SiO2-CaF2 based mold fluxes. The experiments show that there are unstable viscosity-high temperature properties and high T-br in part of CTS slag system, which are bad for lubrication between liquid flux film and strand. And when temperature is below T-br, the viscosities change slowly during cooling in some part of this slag system, which imply that liquid mold fluxes solidify slowly and it is easy to cause surface longitudinal cracks on strand. Major mineragraphy of the CaO-SiO2-TiO2 based mold fluxes are CaO center dot TiO2 or CaO center dot TiO2 and CaO center dot SiO2 center dot TiO2. TiN and Ti(C,N) can be formed in mold fluxes bearing high TiO2 during the continuous casting.