Effect of the primary oxide on the behavior of the oxide precipitating during solidification of steel

Abstract

Effect of the primary oxide on the behavior of the oxide precipitated and grown during solidification was investigated using Mn deoxidized steel which has primary oxides and soluble oxygen before solidification of the steel. The composition and size of oxides in the continuously cast steel were observed and theoretically analyzed. The results obtained are as follows. MnO-FeO and MnO-FeO-Al2O3 oxides were observed. The compositions of the oxides change with cooling rate of the steel and the size of oxide. The Al2O3 content in the oxide at low cooling rate is lower than that at high cooling rate. The Al2O3 content in the oxide decreases with the decrease in the size of the oxide. As a result of the theoretical analysis of the oxide behavior during solidification on the basis of a diffusion growth model, it has been found that MnO-FeO oxide precipitates and grows regardless of primary oxide during solidification and MnO-FeO-Al2O3 oxide grows during solidification as MnO precipitates on the primary oxide which contains Al2O3.