Effect of the Composition of Oxide on the Reaction between Oxide and Sulfur during Solidification of Steels

Abstract

In order to elucidate the reaction between oxides and sulfur in molten steel during solidification, the effect of composition of oxides in continuously cast steels has been observed and analyzed. The results obtained are as follows.
CaO-SiO₂-Al₂O₃ and CaO-SiO₂ oxides are observed in low Al content steel (Al=0.005 mass%) and CaO-Al₂O₃ oxides are observed in high Al content steel (Al=0.031 mass%). CaO-SiO₂-Al₂O₃ and CaO-Al₂O₃ oxides have higher S content than CaO-SiO₂ oxides. High S content in oxides was obtained with high liquid fraction and high sulfide capacity of oxides at the solidification temperature of the steel.
Because desulfurization by oxides which have high sulphide capacity and high liquid fraction occurs during solidification, S segregated in the center of slab is absorbed by the oxides.