Evolution of Equilibrium Composition of MnO-SiO2 and Al2O3-MnO-SiO2 Inclusions in Liquid Fe and Fe-36%Ni Alloy During Cooling

Abstract

Evolution of Equilibrium Composition of MnO-SiO2and Al2O3-MnO-SiO2Inclusions in Liquid Fe and Fe-36%Ni Alloy During CoolingEvolution of chemical composition of inclusions for Fe-36%Ni melt on cooling was simulated on the basis of theoretical analysis. The equilibrium states for deoxidization reactions using manganese, silicon and aluminum were found by using the subregular solution thermodynamic model, including the interaction parameters and the activity coefficients for O, Mn, Si i Al at infinite dilution in iron and nickel. The equilibrium compositions of the inclusions when cooling the melt were computed for Fe-36%Ni for the temperatures from 1873K to 1773K. For comparison, the same analysis was made for pure iron melt. The obtained results indicate different behavior of the inclusions for those melts. For Fe-36%Ni, either MnO-SiO2inclusions or Al2O3-MnO-SiO2ones always increase substantially in MnO content on cooling. When Al2O3content goes up, the effect gets weaker. As to the pure iron melt, the inclusions behave more differently, i.e., the MnO content may go up, go down or stay constant depending on the initial inclusion composition. Despite of the fact that Al2O3-MnO-SiO2inclusions fluctuate significantly as to their compositions for Fe-36%Ni melt, it seems however, that it would be easier for this melt - in comparison to pure iron one - to forecast such a chemical target composition which would allow to achieve the desired composition of the inclusions left within the residual melt after metal cooling from 1873K to 1773 K.