The influence of Al2O3/SiO2 ratio on the viscosity of mold fluxes

Abstract

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 Al 2O3 contents investigated in this study. Increasing X Al2O3/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). © 2008 ISIJ.