Complex deoxidation equilibria of molten iron by aluminum and calcium

Abstract

The influence of oxygen potential in molten steel on the steelmaking reactions, such as desulfurization and denitrogenization by fluxes, is very significant, and it is important to control oxygen content of the molten steel. The use of the strong deoxidizing agents, such as Al and Ca, is effective for decreasing oxygen content of steel, and several researches on the complex deoxidation have been carried out. However, the experimental data do not necessarily accord with the thermodynamically calculated ones, because the reliable thermodynamic data on Ca deoxidation of molten iron are unavailable. In the present study, the complex deoxidation equilibria of molten iron by Al and Ca have been examined at 1 873 K. The oxygen activity in molten iron deoxidized by AI and Ca has been measured by an electro motive force (EMF) method at 1 873 K. The Al-Ca complex deoxidation equilibria are presented, and the validity is confirmed from the present experimental results and the previous ones in the literature on the complex deoxidation by AI and Ca. The Al-Ca deoxidation equilibria presented in the present study can represent the relationship of Fe-Al-Ca-O system more properly than the previously reported ones. © 2005 ISIJ.