Abstract: Taking IF steel as the research object, combined with the production practice of 300 t RH furnace of Shougang Jingtang company, the oxygen content at the end of RH decarburization and the size and quantity of inclusions after deoxidation in the smelting process of IF steel were studied by means of production intensive sampling, data statistics, inclusion scanning electron microscope and other analysis methods. It was found that when the oxygen mass fraction after  RH decarburization was controlled at (290-310)×10^-6, the Al₂O₃ inclusions produced in molten steel were the least. Based on this, the control method of oxygen content at the end of RH decarburization was studied. It was found that the hit rate of oxygen content at the end of decarburization in the forced decarburization mode was high and controllable, and the oxidation of top slag in the forced decarburization mode was weaker than that in the natural decarburization mode, which could reduce the formation of Al₂O₃ inclusions caused by secondary oxidation. The oxygen blowing calculation model was studied and established to ensure accurate control the oxygen content at the end of decarburization, which could improve the cleanliness of molten steel.

Key words: IF steel, RH, precise control of oxygen content, cleanliness