The activities of MnO and SiO2 in the liquid phase region of the MnO-SiO2-CrO, x ternary system saturated with MnO·Cr2O3 solid solution were determined by conducting the equilibrium experiments between the above-mentioned ternary liquid phase and molten iron under the condition of the oxygen partial pressure, PO2=2×10-6Pa at 1873K. By using the thermodynamic data of the MnO-SiO2-CrOx system determined in the previous and the present studies by the authors, the effect of the amount of Si addition on the equilibrium oxygen concentration in molten stainless steel and the composition of non-metallic inclusions under the various conditions of Si-deoxidation process were calculated with the aid of the thermodynamic data related to molten steel. The behavior of inclusions formed during the process is discussed based on the results obtained.
