BEHAVIOR OF OXIDE PRECIPITATION DURING RA PID SOLIDIFICATION OF STEEL

The behavior of oxide precipitation during rapid solidification of ste el was investigated using Ti deoxidized steel. The number, size and co mposition of oxides in rapidly cooled steel have been observed and the oretically analyzed to compare with those in slowly cooled steel and c ontinuously cast slab. The results obtained are as follows. In rapidly cooled steel, whose cooling rate is more than ten times as large as c ontinuously cast slab, many fine oxides smaller than 1 mu m are observ ed. The composition of the oxides mainly consists of Ti2O3, Al2O3 and MnO. The Ti2O3 content in the oxide smaller than 1 mu m is relatively high. By comparing the Ti2O3 content in the oxides larger than 1 mu m between rapidly and slowly cooled steels, it has been found that Ti2O3 content is lower in the rapid cooling than the slow cooling. As a res ult of the theoretical analysis of the oxide behavior during solidific ation, it has been found that the many fine oxides smaller than 1 mu m precipitate and grow during solidification of steel.