The present paper investigates how the XAl₂O₃/XSiO₂ ratio in mold slag compositions in a range between 0.06 and 2.14 influences the viscosity of the melt. The objective was to study the variation in viscosity of mould slags if they get enriched in Al₂O₃ as a result of reactions during continuous casting with high Al containing steel melts for manufacturing TRIP steels.
The viscosity was found to increase with increasing XAl₂O₃/XSiO₂ ratio but a change in the degree of increase was noted at a ratio of 0.57. The effect of increasing temperature was investigated and it was shown that viscosity decreased, as expected, with increasing temperature. An available model in literature for predicting the mold-slag viscosity was empirically modified to account for high Al₂O₃ contents investigated in this study.
Increasing XAl₂O₃/XSiO₂ did not appear to influence the vaporization loss of F but increasing the ratio did influence crystallization by promoting the precipitation of CaF₂ during slow cooling of samples with a high XAl₂O₃/XSiO₂ ratio (0.84 and 2.14).