PSI - Issue 40

Oleg N. Komarov et al. / Procedia Structural Integrity 40 (2022) 231–238 Oleg N. Komarov at al. / Structural Integrity Procedia 00 (2022) 000 – 000

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Keywords: steel, alumothermic reduction, physical and mechanical properties, casting, alloy, microstructure, energy efficient process, wolfram oxide, carbon casting mold.

1. Introduction Decrease in the volumes of primary processing of metal ore materials, non-uniformity of their distribution in the lithosphere (Tkachev and Rundqvist, 2016), and increase in the world consumption of structural steels necessitate the search for resource-efficient methods of manufacturing metal products. Therefore, technologies are developed which are aimed at manufacturing finished products as a result of materials recovery in the metallurgical and processing industries (Reva and Moiseenko, 2013; Lezhnev et al., 2020; Issa and Aleksandrova, 2019; Golubev et al., 2011). In-crease in the world consumption of special-purpose steels determines the demand for ferroalloys which are used in metallurgy as inoculants, deoxidizing agents, and alloying compositions (Tokovoi et al., 2015; Bartlett and Avila, 2016). For instance, high abrasion resistance of steels is achieved by inoculation of iron-carbon alloys with ferrotungsten (Leont’ev et al., 2007). Modern ferrotungsten manufacturing processes are energy -intensive, multi-stage, and involve high-temperature decomposition of ore concentrates in ionic melts (Srinivas et al., 2000; Khat’kov and Boyarko, 2019). The said factors necessitate the search for energy-and-material-efficient processes which would allow for reducing the number of process flow stages required for production of wear-resistant steels, and combining the use of enriched ore materials and technogenic formations in the form of mechanical engineering and metallurgical waste, such as scale and swarf. It appears that such an objective can be accomplished by application of the aluminothermic remelting processes to compositions (Zhenyang, 2019) which contain scale, non-ferrous metal swarf, and ore concentrate. Under production-line conditions, this approach will enable manufacture of a melt outside of the conventional heating units. It is proposed that scheelite concentrate from the Russian deposits be used as a tungsten containing component for manufacture of wear-resistant steel. The operational procedure of aluminothermic remelting includes fractional separation of thermite mixture components, drying them at high-refractory facilities made of graphitized carbon or magnesite, initiation of exothermic process by igniting a fuse placed on the surface of the thermite composition, and production of a melt at the temperatures of 2,500 – 2,700 0 C due to the sequential advance of the front of the liquid phases in the reactor in the direction top-down, which is cast into a mold once the reaction is complete (Merzhanov, 1994). In order to experimentally simulate the process of producing a wear-resistant iron-carbon alloy, tungsten containing scheelite concentrate was introduced into the thermite. 0 – 20% value range was adopted for scheelite concentrate content in the experiment; the concentrate was admixed to the thermite prepared beforehand. The iteration increment for scheelite concentrate content in the thermite amounted to 5%. The scheelite concentrate used in the experiment is mined in the Far East of the Russian Federation (Verkhoturov et al., 2010); its chemical composition is as follows: WO 3 = 53÷59%, P = 1.7÷2.0%, Mo = 0.021%, S = 0.25÷0.3%, As = less than 0.005%, SiO 2 = 2÷4.6%, CaO = 29%. The information on the practical application of the aluminothermic process with the use of ore concentrates is very limited in the modern processes of manufacturing metal castings with improved resistance abrasion. As a result of the experimental simulation of the aluminothermic process of manufacturing castings from iron-carbon alloys, it is assumed that a number of factors of the process under consideration will lead to the formation of complex phases containing tungsten, which will provide for high wear-resistance of the end products. The results of the studies are focused on energy- and material-efficient recovery of tungsten from ore concentrates, which will enable extension of the application range of castings produced by aluminothermy 2. Purpose and objectives Purpose of the paper: determine the relationship between the mechanical characteristics of the samples of iron carbon alloys produced by aluminothermic remelting of compositions and the reductant – scheeliteconcentrate quantitative ratio therein. In order to achieve this purpose, the following objectives were set: