Silicon Deoxidation Equilibrium of Molten Fe–Mo Alloy

Abstract

In order to control the silicon deoxidation reaction for steel including molybdenum, it is necessary to take into account the thermodynamic affinity of molybdenum with silicon. For the calculation of the deoxidation equilibria in the alloyed steel including molybdenum, it is necessary to know the interaction parameter of molybdenum for silicon. However, it is difficult to explain the silicon deoxidation of the alloyed steel including molybdenum by previously reported thermodynamic data. Accordingly, the equilibrium for silicon distribution between Fe and Ag phases in Fe–Ag–Si–Mo system and the deoxidation equilibrium of molten Fe–Mo alloy with silicon are investigated at 1873 K. The atomic fraction interaction parameter of Mo for Si, ε_{Si (in Fe)}^Mo, is determined to be 43(±13) from the equilibrium for silicon distribution between Fe and Ag phases in Fe–Ag–Si–Mo system. The experimental results on the deoxidation equilibrium of molten Fe–Mo alloy with silicon reasonably agree with the calculated ones by using ε_{Si (in Fe)}^Mo=43(±13) derived in the present study. The oxygen contents after the deoxidation treatment by silicon are estimated for 8 kinds of steel. The oxygen content of ferrous alloys including molybdenum can be reasonably estimated using the interaction parameter of Mo for Si derived in the present study.