Determining the physical-chemical characteristics of the carbon-thermal reduction of scale of tungsten high-speed steels

• Main Authors: Stanislav Hryhoriev, Artem Petryshchev, Karina Belokon’, Kristina Krupey, Mykhail Yamshinskij, Grigoriy Fedorov, Dmytro Stepanov, Andrii Semenchuk, Elena Matukhno, Alexander Savvin
• Format: Article
• Language: English
• Published: PC Technology Center 2018-03-01
• Series: Eastern-European Journal of Enterprise Technologies
• Subjects: alloyed technogenic wastes; high speed steel; carbon-thermal reduction; microscopic analysis; carbide formation
• Online Access: http://journals.uran.ua/eejet/article/view/125988
• ISSN: 1729-3774; 1729-4061

We determined that scale of the high-speed steel R18 is composed of the phases of Fe3O4, Fe2O3, FeO, with the presence of alloying elements as the replacement atoms. The microstructure is disordered and non-uniform. In the examined area, in addition to Fe, we revealed the presence of, % by weight: W – 16.34, Cr – 2.68, V – 1.82, and others. The content of O was 15.32 %. It was established that the reduction of scale at 1,523 K proceeds with the formation of α-Fe and carbides Fe3W3C, (Fe, Cr)7C3, W2C, V2C, Fe3C, Fe2C. Manifestation of carbides of alloying elements decreased with an increase in the degree of reduction. The microstructure of reduction products is heterogeneous, containing particles with a different content of alloying elements and has a spongy structure. The conditions are provided for the absence of phases subject to sublimation. We conducted experimental-industrial tests of using the metallized scale while smelting high-speed steel with a degree of disposal of alloying elements at the level of 92‒94 %. Improvement of environmental safety was implemented by the replacement of reduction melting with the newest methods of powder metallurgy employing the solid-phase reduction.