Thermodynamic Analysis of the Oxidation Behavior of Cerium in High‐Speed Steel during Electroslag Remelting

Abstract

Cerium loss is difficult to be avoided during the electroslag remelting (ESR) process. To reduce the cerium loss in high‐speed steel during the ESR process, the present study investigates the thermodynamics of cerium oxidation in cerium‐containing high‐speed steel based on the thermodynamic calculation and laboratory‐scale steel–slag reaction experiments. The results show that the reactions between [Ce] and (Al2O3), as well as [Ce] and (MgO) contribute to the cerium loss in the steel. Increasing the contents of CaF2 and MgO in the slag, the activities of Al2O3 and Ce2O3 show a slightly decreasing trend. The addition of CaO and Ce2O3 significantly reduces the Al2O3 activity but enhances the Ce2O3 activity. MgO activity shows an insignificant change with the contents of CaO and Ce2O3, while it decreases with adding Al2O3 and CaF2. Reducing Al2O3 content and enhancing Ce2O3 content in the slag are feasible to increase the cerium yield in the steel. With increasing Al2O3 content from 16.93 to 26.92 wt%, the cerium yield decreases from 8.4% to 6.0%. Increasing Ce2O3 content from 3.98 to 11.01 wt% enhances the cerium yield from 6.0% to 16.9%. The actual soluble Ce content in equilibrium with slag is almost less than 0.001 wt%.