Physicochemical prediction of the types of nonmetallic inclusions: Complex deoxidation of steel with aluminum and calcium

Abstract

The complex deoxidation of steel with aluminum and calcium is used as an example to analyze the state of the art in the methods of physicochemical prediction of the types of nonmetallic inclusions forming during ladle treatment of steel. The uncertainty existing in the thermodynamic description of the simplest object of metallurgical technologies, i.e., iron-based dilute liquid solutions, is shown to lead to radically different versions of the oxide-precipitation diagram of the Fe-Ca-Al-O system. The physical causes of this discrepancy are revealed. It is demonstrated that the concentration and temperature dependences of the thermodynamic properties of iron melts can be well approximated using an approach based on the concept of associated solutions. This approach has been used to adequately interpret the reactivity of calcium in iron-based solutions for the first time. The modern methods of physicochemical prediction of the types of nonmetallic inclusions in steel are noted to require detailed theoretical and experimental grounds.