Removal of Harmful Impurities from a Steel Melt during ESR under Various Current Conditions

Abstract

ESR is definitely the most variable technology for secondary remelting of steels and alloys. Furnaces of this technology have wide possibilities for design modification and the use of fluxes and alloying components to stabilize and adjust the physicomechanical properties and chemical homogeneity of the resulting ingots. Due to its technological flexibility and simplicity, ESR can improve both its productivity and refining ability. The refining ability of ESR in terms of removing harmful impurities and gases changes significantly when the current mode of an ESR furnace changes. When reversed polarity is used, effective desulfurization and deoxidation of a metal are maintained. Effective nitrogen removal is ensured primarily by a slag mode, in which there is a sufficient amount of lightweight nitride-forming components. In addition, it is also important to observe reversed polarity to remove nitrogen ions with a negative oxidation level, similarly to oxygen and sulfur. The use of straight-polarity direct current makes it possible to impart a new property to ESR, namely, hydrogen removal; together with a change in the location of a heat center on the metal bath surface, it improves the technical and economic indicators of ESR technology.