Thermodynamics on the Formation of Non-metallic Inclusion of Spinel (MgO·Al<SUB>2</SUB>O<SUB>3</SUB>) in Liquid Steel

The non-metallic spinel inclusion, MgO·Al2O3, has a high melting point, and produces an undeformed C-type inclusion in steel products.Therefore, it is very harmful in the production of high grade wire, spring and bearing steels.Thus it is necessary to develop a methodology by which we can predict the occurrence of such inclusion.Dolomite crucible was used to increase the magnesium content in liquid iron in the present experiment on thermodynamics of spinel formation.Discussed is the thermodynamics of the formation of spinel non-metallic inclusions during co-deoxidation with aluminum and magnesium in the present work, based on the previous work of deoxidation equilibrium with magnesium, calcium and aluminum in liquid iron by the authors in order to evaluate the activities of oxygen and dissolved deoxidizers in the thermodynamic description by the first and second order interaction parameters including the cross product terms.