Improvement of steel cleanliness by controlling slag composition

The properties of slag are very important in the improvement of steel cleanliness. In particular, the value of %CaO/%Al2O3 ratio, slag basicity, fluidity, and oxygen activity in the slag are considered to affect the steel cleanliness directly. To control these values effectively, the method of deoxidation and slag composition control via additives has been changed. The effect of oxygen content before tapping was investigated. By optimising these factors, the total oxygen content of bearing steel was reduced from 12 to 8 ppm.