Thermodynamic analysis of processes in the high-temperature polycomponent Fe–Y–Si–O–C system

Abstract

In the production of low-carbon and high-quality steels, it is recommended to use special complex alloys of rare earth metals for deoxidation, microalloying and modification. To elucidate the mechanism of action of each of the components of the alloy, it is necessary to differentiate the action of each individual element. Yttrium is usually classified as a rare earth metal, but its deoxidizing and modifying ability deficiency studies. The use of yttrium applica-tion is known to increase in density, ductility, scale resistance, resistance to high-temperature corrosion of steel, effec-tively affects the shape, size and distribution of non-metallic inclusions. This paper consider the interaction of yttrium, silicon, and carbon with oxygen dissolved in liquid iron. Nonmetallic inclusions formed in this case can be identified on the state diagram of the FeO–Y2O3–SiO2 oxide system. This diagram is absent in the literature; therefore, it was mod-eled on the basis of the available binary phase diagrams of the FeO–Y2O3, FeO–SiO2, and Y2O3–SiO2 systems. Com-plex deoxidation by yttrium and silicon is possible only at yttrium concentrations in liquid iron less than 0.0001% (ox-ide melt or yttrium silicates are formed as non-metallic inclusions). If the concentration of yttrium is higher than this value, then it is the only deoxidizer. In the presence of carbon, liquid non-metallic inclusions can form in a very narrow range of liquid metal compositions, and the main oxide non-metallic inclusion is yttrium oxide. At yttrium concentra-tions below 0.0001% and silicon concentrations up to 1%, only carbon is the deoxidizer. Taking into account the previ-ously studied Fe–Y–Me–O–C (Me–Ca, Mg, Al, Cr) systems, a thermodynamic data base was created for designing the compositions of complex yttrium-containing ligatures.