Promising directions of using aluminum for steel deoxidation

Abstract

The existing methods of deoxidation and alloying of steel with aluminum are considered and analyzed. The most promising methods of introducing aluminum into the iron-carbon melt are proposed, which make it possible to significantly increase its effective utilization factor. Based on the analysis of data on improving the shape and design of an aluminum ingot by using weighting agents made of cast iron and steel in various versions, a technology for production of a bimetallic aluminum-iron ingot with a displaced center of gravity has been selected and described, which reduces the contact surface of interaction with atmospheric oxygen and thereby increase assimilation of aluminum due to the implementation of the “self-righting doll” effect. On the basis of industrial testing under the conditions of Dneprostal Metallurgical Plant with preliminary deoxidation of the melt at the tapping from an electric arc furnace into the ladle, attention is focused on advantages of using fractionated complex alloys of the Fe - Al - Si system instead of the secondary pig aluminum with a replacement ratio of 1: 1.25, which enables to increase the degree of aluminum use by more than 40%. The mechanisms of the process of spontaneous destruction of alloys of the Fe - Si system are described, by analogy with which the regions of the ξ-phase existence in the ternary Fe - Al - Si system are identified and, taking into account the theory of embrittlement of intermetallics, a technological solution is proposed for stabilizing ferrosilicoaluminum from spontaneous disintegration during long-term storage in any weather conditions and a wide range of concentrations by modifying the alloy with an alloy based on rare non-ferrous metals. For these purposes, under the conditions of SPP Vasilkovsky Ore Reduction Plant Ltd., a pilot batch of a complex aluminum-silicon alloy on an iron base (~ 30% Al, ~ 15% Si, bal. - Fe) was melted in an induction furnace with the use of the modifying additive.