The Application of an Effective Equilibrium Reaction Zone Model Based on CALPHAD Thermodynamics to Steel Making

Abstract

TCOX9 is a thermodynamic database (developed using CALPHAD) which describes the thermochemical interactions between liquid steel and slag during steel making and refining. It contains all the major steel alloying elements (Fe–C–Co–Cr–Cu–Mn–Mo–Nb–Ni–V–W–Ti) as well as the most important slag elements (Ca–Mg–Si–Al–F–O–P–S). The ionic liquid model describes the liquid phase over the whole composition range from metallic liquid (steel) to oxide liquid (slag). The database also contains the most important metallic and non-metallic solid phases, allowing the calculation of inclusion formation, inclusion modification, steel solidification, slag solidification, steel–refractory reactions, slag–refractory reactions, and steel–mould powder reactions. For use with this database, a new process metallurgy module has been developed within Thermo-Calc which makes it easy to set up calculations for steel and slag. An extension to the module is under development that incorporates a kinetic model of the steelmaking process based on the concept of effective equilibrium reaction zones. This model is outlined in detail in this paper and applied to a ladle furnace steel refining process.