Study into the structural­phase transformations accompanying the resource­saving technology of metallurgical waste processing

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Phase composition and microstructure of the doping alloy obtained by regenerative smelting of technogenic wastes were studied. This is necessary to determine technological characteristics that increase the degree of extraction of doping elements during the processing of technogenic raw materials and subsequent use of the alloying material. It was determined that at a Si:C atomic ratio in the charge at a level of 0.05-0.19 (O:C atomic ratio is 1.25), a solid solution of carbon and doping elements in γ-Fe, Fe 3 Si, and Fe 5 Si 3 was found in the alloy. At Si:C atomic ratio at a level of 0.05 in the alloy, a solid solution of carbon and alloying elements in γ-Fe was dominating with a weak manifestation of Fe 3 Si. When the value of Si:C atomic ratio was increased to 0.09, Fe 5 Si 3 was found together with Fe 3 Si. A gradual increase in Si:C atomic ratio to 0.09, 0.12, and 0.19 led to a higher manifestation of Fe 3 Si and Fe 5 Si 3. The microstructure of the alloy in the entire studied range of Si:C ratio values in the charge was characterized by the presence of several phases with different contents of doping elements. The content of elements in the studied areas (at. %) was 1

Section: Discussion Of the Results Obtained In Studying The Propertiesupporting

confidence: 94%

Section: Literature Review and Problem Statementsupporting

confidence: 83%

Section: Literature Review and Problem Statementmentioning

confidence: 98%

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Identifying the features of structural and phase transformations in processing the waste of metallurgical products doped with refractory elements

Volokh¹,

Kim²,

Fesenko³

et al. 2020

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“…One should note the results of studying the carbon-thermal treatment of anthropogenic waste of unalloyed steels reported in work [3], which identified the phases of iron, carbide of iron, and carbon in the reduced material. Similar data were acquired by the authors of papers [4,5] when studying the reduction of doped anthropogenic waste with carbon and silicon. The reduced material revealed a phase of iron with dissolved doping elements, as well as silicides and iron carbides.…”

Section: Introductionsupporting

confidence: 66%

“…It considered the reduction of oxide waste of doped steels, containing, among others, chromium and molybdenum, with carbon. In the products of the reduction smelting of doped waste involving carbon and silicon, the authors of paper [5] identified the phase of iron and Fe 3 C. The Fe 3 C silicide formation also took place in the Fe-Cr-C-Si system in work [6] that investigated a coating made from the 45Fe39Cr6C10Si alloy. Consequently, the reduction of oxide waste of doped steel using silicon can be accompanied by the formation of iron silicides with dissolved doping elements as substitution atoms.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Identification of patterns in the structural and phase composition of the doping alloy derived from metallurgical waste processing

Poliakov

Dzyuba

Volokh

et al. 2021

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This paper reports a study into the structural-phase composition of the doping alloy made by processing metallurgical anthropogenic waste involving reduction smelting. This is required for determining the technological parameters that ensure an increase in the level of extraction of target elements during the processing of anthropogenic waste and for the further use of the doping alloy. It was revealed that the phase composition of the doping alloy manifested a solid solution of the doping elements and carbon in α-Fe. Cementite Fe3C and silicides Fe5Si3, FeSi, and FeSi2 were also identified. In this case, the doping elements were more likely to act as substitution atoms. It has been determined that the microstructure of the alloy consisted of several phases of different shapes and contents of the basic doping elements. Sites with an elevated iron level of up to 95.87 % by weight in the composition could be represented by the solid solution phase of the doping elements and carbon in α-Fe. The sites with a relatively high (% by weight) content of carbon (0.83‒2.17) and doping elements ‒ W, up to 39.41; Mo, up to 26.17; V, to 31.42; Cr, to 9.15 ‒ were apparently of a carbide nature. The sites with a silicon content of 0.43‒0.76 % by weight likely included silicide compounds. The alloy's characteristics make it possible to smelt steel grades without strict carbon restrictions, replacing some of the standard ferroalloys. Neither phases nor compounds with a relatively high propensity for sublimation were identified in the material produced. Therefore, there is no need to provide conditions to prevent evaporation and loss in the gas phase of the doping elements. That could increase the degree of extraction of the doping elements

Defining the features of structural and phase transformations in the recycling of anthropogenic metallurgical waste containing refractory elements

Volokh

Poliakov

Yamshinskij

et al. 2022

This paper reports a study into the features of the phase composition and microstructure of a master alloy obtained by using the reduction melting of oxide man-made waste. That was necessary to define those technological indicators that provide for an increase in the degree of extraction of alloying elements during the recycling of anthropogenic raw materials and the subsequent use of the alloying material. It has been determined that the phase composition of the alloy at a Si:C ratio in the charge of 0.11 mainly consisted of a solid solution of elements in α-Fe, as well as carbides Fe3C and Fe3W3C. At the Si:C ratios in the charge of 0.28 and 0.52, along with a solid solution of the elements in α-Fe, Fe8Si2C, Fe5Si3, and FeSiC, FeSi2 manifested themselves, respectively. The microstructure of the alloy demonstrated a clear manifestation of several phases with different content of alloying elements. Changing a Si:C ratio in the charge from 0.11 to 0.28 and 0.52 led to an increase in the residual silicon content (wt %) in the studied areas, from 0.00–0.25 to 0.12–1.79 and 0.20–2.11, respectively. At the same time, the carbon content (wt %) in the examined areas varied from 0.25–2.12 to 0.24–2.52 and 0.45–2.68, respectively. The content of alloying elements in the investigated areas varied within (wt %): W – 0.00–43.06, Mo – 0.00–32.72, V – 0.19–20.72, Cr – 0.69–33.94, Co – 0.00–3.96. Analysis of the study’s results reveals that the most acceptable ratio of Si:C in the charge is 0.52. In this case, there is a certain content of residual silicon along with carbon in the form of carbosilicide and silicide compounds. Such indicators of the alloy provide sufficient reducing capacity of the alloy when used. The properties of the alloy make it possible, when smelting steels, to replace part of those standard ferroalloys that do not have strict carbon restrictions.