Activities of MnO and SiO_2 in the MnO-SiO_2-CrO_x Melt and Equilibrium Relation among Inclusions of This Ternary System and Molten Stainless Steel during Si-deoxidation Process

摘要

The activities of MnO and SiO_2 in the liquid phase region of the MnO-SiO_2-CrO_x ternary system saturated with MnO centre dot Cr_2O_3 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, P_(O_2) = 2 x 10~(-6) Pa at 1873K. By using the thermodynamic data of the MnO-SiO_2-CrO_x 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.