Research and development of the technologies aimed at reducing the effects of global warming are very relevant. The paper presents the results of an analysis of global warming in the Earth’s atmosphere in connection with the natural and enhanced greenhouse effect and provides an assessment of the possible impact of metallurgical production on the formation of an enhanced greenhouse effect. Metallurgy is known to contribute about 8 % of anthropogenic CO₂, which is significantly less than energy (24 %), land use (18 %), transport (14 %) or agriculture (14 %). About 80 % of the “metallurgical” CO₂ is supplied by the blast furnace process, therefore, one of the main tasks of metallurgy in combating global warming is to replace the technology for producing pig iron in blast furnaces with direct iron reduction (DRI) technology of the Midrex type. At the same time, decommissioning of blast furnaces will take a considerable amount of time, and a polyhybrid technology for decarbonization of iron oxide reduction processes in a blast furnace is proposed for this transition period. This technology consists in initiating the water gas shift reaction (WGSR): {H₂O} + {CO} \( \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} \) {H₂} + {CO₂} + Q (−∆H) by supplying water vapor {H2O} to a furnace. As a result of thermodynamic analysis of the hydrogen formation process {H₂}, the temperature was established (approximately 1093 K (820 °C)), at a decrease of which, in accordance with the Le Chatelier principle, the reaction equilibrium constant and the released hydrogen amount increase. Based on this, the temperature profile of any blast furnace can be used to determine the initial level for placing steam supply devices in the furnace working space. Since the WGSR reaction is exothermic, it should be expected along with the intensification of the iron reduction process and coke saving. The proposed technology does not conflict with other decarbonization processes, complementing and increasing the effectiveness of their action. The considered scheme of using steam to intensify the iron reduction process takes into account the possibility of developing and applying artificial intelligence elements with the specifics of automation and control of this process. The authors declare the priority of their proposed polyhybrid technology for decarbonization of iron oxide reduction processes using hydrogen generated as a result of a heterogeneous catalytic process based on the reaction of water gas.

The present study addresses numerical modeling of the solidification front dynamics in an electroslag remelted (ESR) ingot, achieved through targeted adjustment of the trajectory of molten electrode metal drops falling into the slag bath. Particular emphasis is placed on analyzing the effect of forced rotation of the consumable electrode on the spatial distribution of temperature fields and morphology of the solidification boundary. Numerical experiments were conducted for an industrial-scale ESR unit equipped with a water-cooled copper crystallizer (90 mm in diameter) and a consumable electrode (40 mm in diameter). Development of a digital twin based on computational fluid dynamics and magnetohydrodistics principles enabled accurate reproduction of the actual production process and identification of heat and mass transfer patterns. Analysis of temperature gradients allowed precise localization of zones with maximum heat generation. Visualization of numerical fields near the steel solidus temperature confirmed the radial shift of the drop trajectory toward the periphery of the slag bath within the range of 25 – 35 mm. The mathematical model consistently integrates Maxwell’s equations for electromagnetic field calculation, conservation laws of mass and momentum, and thermal kinetics accounting for Joule heating. Numerical calculations under direct current polarity demonstrated that centrifugal displacement of drop transfer, combined with reversal of convective flows, promotes formation of a stable horizontal solidification front. This modification substantially enhances structural homogeneity of the ingot and minimizes the thickness of transition zones between layers in multilayer castings. A critical range of electrode rotation speeds was established; exceeding this threshold destabilizes the meniscus, enlarges drops, and deteriorates product quality. The obtained theoretical results fully correlate with full-scale experimental data. The model was verified by comparing calculated and experimental data on position of the interfacial boundary. The scientific substantiation of implementing controlled electrode rotation for optimizing thermal process parameters, ensuring stable metal quality, and improving overall energy efficiency of metallurgical production is provided.

Significant amounts of iron-containing steelmaking and blast furnace sludges with elevated zinc content accumulated on the territories of ferrous metallurgy enterprises. It is not possible to recycle these sludges into the blast furnace process for iron recovery, because zinc leads to the formation of scaffold buildups in the blast furnace throat zone; nor are they suitable for electric arc furnaces, as the iron in them is in an oxidized form. At the same time, zinc-containing sludges can become a valuable secondary product. Extracting zinc from these sludges is difficult, since zinc is present not only in oxide form but also, to a significant extent, in sulfate or sulfide forms. In this work, the possibilities of zinc extraction from sludges were evaluated using the FactSage software package. Direct carbothermic reduction of zinc sulfide requires temperatures above 2000 °C, which is technologically unattainable in most industrial units. An alternative, patent-protected approach was substantiated and thermodynamically evaluated: introducing calcium and magnesium carbonates (limestone, dolomite) into the charge before waelzing. Upon heating, limestone decomposes to form CaO, which undergoes an exchange reaction with ZnS, converting it into ZnO, after which zinc oxide is reduced by carbon at 1100 °C. Gibbs free energy calculations confirm the feasibility of zinc extraction via the proposed mechanism in the range of 1000 – 1200 °C. The effectiveness of the technology was experimentally demonstrated using sludges from the blast furnace and open-hearth shops of JSC EVRAZ NTMK with an initial zinc content of approximately 5 wt. % (in the form of Zn₃O(SO₄)₂). After roasting briquettes at 1200 °C, the residual zinc content decreased to a fraction of a percent, the degree of iron metallization reached 72 %, and zinc is not detected by phase analysis. Two marketable products were obtained – zinc sublimate and zinc-free metal flux, suitable for return to the metallurgical process.

In 2023, 16,174 thousand tons of FeCr were produced worldwide, and in 2024 – 18,509 thousand tons. The authors collected the data on the production of chromium ferroalloys in 15 countries. The structure of the 20 largest ferrochrome (FeCr) manufacturing companies in China, Africa and Europe is given. The paper describes the projects for the launch of new FeCr production facilities in countries around the world. The production parameters (FeCr composition, cost, electricity consumption) of obtaining high carbon FeCr depending on the content of Cr₂O₃ and Cr₂O₃/FeO in the raw materials were analyzed. FeCr production technologies are considered, taking into account a large proportion of fine fraction raw materials. The paper presents the measures to reduce the consumption of electricity and coke. The advantages and disadvantages of alternating current and direct current furnaces, plasma furnaces, and microwave heating are considered, as well as the used reducing agents, and much attention is paid to the use of “biochar” today. Information on the studies related to the reduction of CO₂ emissions from the production of FeCr is provided. The volume of production and consumption of chromuim ferroalloys in the Russian Federation is considered with description of the structure of manufactured chromium ferroalloys by type (high-, medium- and low-carbon FeCr, metallic chromium, nitrided chromium and ferrochrome, chromium ligatures). In 2017 – 2022, the volume of production of chromium ferroalloys in Russia averaged 420 thousand tons per year (excluding ligatures and metallic chromium). The main enterprises specializing in the production of chromium ferroalloys in Russia are presented, indicating their productivity. In Russia, FeCr consumption is only 10 – 30 % of produced, so the domestic ferrochrome market is in a state of overproduction and is export-oriented. In recent years, the volume of FeCr production in the Russian Federation sharply decreased. The authors describe the reasons for the sharp decrease in FeCr export and production in Russia.

The complex of studies carried out in order to substantiate the directions for improving the modes of purging rail steel with inert gas in a ladle in relation to the conditions of steel treatment in the operating ladle furnace of an industrial electric steel workshop includes mathematical modeling and statistical analysis. According to the research results, a significant effect of increasing the intensity of argon injection through bottom porous plugs in a wide range of changes in this parameter (from 2 to 85 m³/h) was established on an increase in indicators characterizing the efficiency of mixing and refining steel from non-metallic inclusions (mixing power and effective diffusion coefficient). The authors, in relation to the rails of the studied enterprise current production, using optical and electron microscopy techniques, determined that at low contamination of the rails bulk with non-metallic inclusions at individual heats, inclusions accumulate, which are the causes of the internal defects formation and rejection of rails during ultrasonic quality control in the production stream. Based on the results obtained, a new method for purging rail steel was developed with a dedicated period of intensive purging lasting about 20 % of the total argon purging time. Pilot testing of the developed purging mode on a series of 76KhF rail steel heats of current production (115 heats) showed a significant (by 0.31 abs. % or 11 rel. %) reduction of rail rejection by non-metallic inclusions relative to the comparison base. The additional metallographic studies confirmed the reduction of contamination with non-metallic inclusions of rails made of steel treated with a new argon purging mode in a ladle. 

The paper describes the effect of boron, manganese, and sulfur in low-carbon pipe steel on the composition and size of nonmetallic inclusions, microstructure, and mechanical properties. Generalization of the results of the study of nonmetallic inclusions in low-carbon pipe steel microalloyed with boron made it possible to identify three main groups of nonmetallic inclusions in the studied samples of hot-rolled products: oxide-sulfide and oxysulfide, oxide, and sulfide inclusions. In the rolled product sample [B] = 0 %, nonmetallic inclusions of no more than 4 μm in size are represented as single inclusions or sulfide films, as well as silicate inclusions. Samples of rolled products with boron are characte­rized mainly by small rounded nonmetallic inclusions: silicate inclusions and complex inclusions consisting of oxide phase of the Al₂O₃ – MgO system in a shell of manganese and calcium sulfides. When boron is introduced in an amount of 0.006 – 0.011 %, the structure changes from ferrite-pearlite to ferrite-bainite, with a decrease in the average size of the ferritic grain; at 0.011 %, from 8.7 to 6.8 μm. Microalloying of low–carbon pipe steel with boron in the amount of 0.006 – 0.011 %, containing 1.4 – 1.6 % Mn and 0.003 – 0.011 % S, due to the predominant formation of a finely dispersed ferrite-bainite structure and rounded nonmetallic inclusions of no more than 5.0 μm in size, provides high strength properties and, as a result, the production of hot-rolled metal with a thickness of 10 mm of X80 strength category without heat treatment. Economically manganese alloyed pipe steel containing 0.006 % B, 1.4 % Mn and 0.003 % S has the best mechanical properties, high processability and good weldability, with a carbon equivalent of С_eq = 0.30 % at a rate of not more than 0.45 %, a crack resistance coefficient of Р_см = 0.17 % at a rate of not more than 0.25 % and a ratio of σт /σв = 0.85 at a rate of not more than 0.90.

The durability of machine-building parts is limited by the permissible degree of wear. During the heat treatment of parts in magnetic field, changes in the structure and mechanical properties of materials are noted, therefore it seems important to evaluate the effect of this technology on wear resistance. Such an assessment can be carried out using laboratory, bench and field tests. The purpose of this work was to evaluate the changes in the indicators characterizing wear during heat treatment operations with the application of a permanent magnetic field in compa­rison with standard treatment modes. Magnetic fields of the order of 1.5 MA/m were obtained in the interpolar gap of the FL-1 electromagnet. The studied samples were made of U8 steel and ductile ferritic cast iron KCh 33-8, which were quenched at a furnace heating temperature of 1000 °C. The samples were tested by friction against fixed abrasive particles under constant load on Kh4-B friction machine according to the traditional method. The maximum effect in increasing wear resistance is observed after quenching the parts in a magnetic field. Low tempering slightly reduces wear resistance, which is caused by increased plasticity and changes in the fracture mechanisms. After quenching in magnetic field, tempering also in magnetic field allows one to maintain wear resistance at a higher level. After heat treatment in magnetic field, there is a decrease in breakouts and discoloration (brittle fracture) along the edges of scratches from abrasive particles. Statistical analysis of the profiles of friction surfaces indicates a greater uniformity in the arrangement of structural barriers for the microstructure of steel treated with magnetic field. Comparative bench and field tests showed the effectiveness of heat treatment in magnetic field, which provides an increase in wear resistance of agricultural machine parts up to 1.4 times.

The authors studied plastic deformation of rail steel under tension and compression conditions. Under the conditions of tensile deformation, after reaching a yield strength of 1037.9 MPa, a parabolic hardening stage is observed, followed by a pre-fracture stage. Under conditions of compression deformation, material destruction does not occur, only a linear hardening stage is observed. The compressive yield strength was 1034.2 MPa. The results obtained were discussed using an autowave plasticity model, in which three order parameters were introduced. The first order parameter is the amplitude of unstable mode of inelastic deformation. The second order parameter is the amplitude of elastic deformations, which characterizes the change in the material volume during deformation. The third (control) order parameter is the amplitude of the lattice curvature. The first two order parameters are responsible for the formation of an autowave, and the third determines its type and nature of propagation. Based on the analysis of the kinetic equations of the order parameters, it was established that the presence of lattice curvature leads to a slowdown in the formation of both running and static deformation localization bands at the linear and parabolic stages, respectively. It is shown that the curvature affects the propagation of a running autosoliton. If at θ = 0 the autosoliton does not damp, then at θ > 0 the attenuation of the running autosoliton is observed. It is assumed that the absence of rail steel destruction of during compression after the end of the linear stage is due to the formation of an irregular wave pattern first, and then due to a running damping autosoliton.

Modern liquid steel production technology provides the maximum iron content (more than 99 %), and the minimum impurity content at the final stage of electric smelting, as well as during metal tapping into a ladle with deoxidation and desulfurization. Many years of production experience show that one of the most important reserves for reducing the structural and chemical heterogeneity of steel and improving the quality of steel products in the steel industry is to develop the smelting technology and obtain an equilibrium, maximally homogeneous melt before crystallization. Metal crystallization occurs from a nonequilibrium state, which increases the chemical and physical heterogeneity of solid metal, reduces its service characteristics and leads to significant deviations in its quality from heat to heat. There are different ways to bring the melt into equilibrium. The most accessible way to obtain an equilibrium melt is through high-temperature exposure. Experimental work in the conditions of JSC “Vyksa Metallurgical Plant” showed that melt preparation for crystallization by thermal-time treatment (TTT) affects the solidification process and improves the microstructure and properties of solid metal. It is suggested to carry out a high-temperature effect of TTT on the melt precisely at the stage of smelting in an electric arc furnace (EAF).

Molecular dynamics simulation was used to study the compressive deformation of austenite nanoparticles with a nanocrystalline structure at low temperatures. The authors studied the influence of nanoparticle size (from 2 to 20 nm) and crystalline grain size (from 2 to 8 nm) on their strength and on the value of compressive deformation at which maximum stress is achieved. The characteristics of plastic deformation in the case of nanoparticles with a nanocrystalline structure are highlighted. Uniaxial compression of the nanoparticle was simulated in the model by moving virtual planes on both sides of the particle with a constant velocity of 10 m/s at an initial temperature of 0 K. The study demonstrated that the nanoparticles strength decreases with decreasing average grain size. While the size of the nanocrystalline particles themselves decreases, as with single-crystal particles, their strength increases. The authors also found that with decreasing particle size, the value of deformation, at which maximum stress is achieved during nanoparticle compression, increases. A decrease in grain size leads to a decrease in strength, which is associated with the primary mechanism of plastic deformation of metal particles with a nanocrystalline structure: grain boundary sliding. During the first stage of deformation, the entire particle structure typically rotated until the maximum value of the stress vector projection onto the preferred shear plane was reached. In the case of a nanocrystalline structure, this was determined by the relative orientation of the grain boundaries. Grain boundaries, roughly aligned along the same plane, represented the preferred shear plane in this case.

The work is devoted to the description of the process of forming the structure of carbide steel (high-speed steel 10R6M5 + 5 – 20 wt. % of tungsten monocarbide WC) during crystallization and cooling after induction surfacing. Theoretically, the chain of transformations in liquid-solid and solid states is considered. It was experimentally shown that the crystallization process begins with a peritectical transformation. Upon further cooling, as a result of eutectic transformation, ledeburite eutectic is formed with carbides of Me₆C and Me₁₂C types. Simultaneously with the precipitation of tungsten ledeburite, crystallization of VC carbides begins, which in pure 10R6M5 steel and in carbide steel with a small amount of WC precipitate mainly in the form of separate isolated carbide precipitates. An increase in the amount of WC hardener introduced into the charge leads to predominantly eutectic crystallization of VC carbide. The morphology of primary tungsten-molybdenum ledeburite also changes from fan-shaped in pure 10R6M5 steel through a number of modifications to the classic skeletal, characteristic high-tungsten R18 steel type, in carbide steel with a significant amount of introduced WC carbides. As the deposited layer cools, two-phase transformations occur in it, leading to the precipitation of carbides such as WC, W₂C, cementite, etc. In the microstructures of all surfacings, martensite crystals are observed, caused by hardening of the deposited layers when they are cooled in air. With induction surfacing, it is possible to adjust the processes described above by selecting such modes that partially or completely allow you to “inherit” the structure of the initial deposited pressing. As a result, it is possible to prevent the precipitation of ledeburite to a greater or lesser extent and fix the WC carbide hardener in the form of groups of angular carbides around the “powders” of the fused 10R6M5 steel. Thus, the determining role of the processes occurring in the upper temperature range of crystallization (precipitation of solid solutions and release of eutectic) on the structure formation of carbide steel is shown.

The article discusses the problem of optimizing technological modes of metallurgical processes. The main stages of solving an optimization problem, justification and principles of selecting an optimization criterion, methods for solving multi-criteria vector optimization problems are considered. The authors developed a method for modeling and optimizing metallurgical processes. When implementing the method, two-loop optimization is performed by solving two types of multi-criteria optimization problems: finding the system parameters when determining the optimal conditions for the processes in the first loop, and determining the optimal modes of metallurgical technologies in the second loop. Calculation of optimal technological modes for metallurgical processes involves determining the control actions required to obtain a product of the specified composition and temperature while optimizing technical and economic indicators. To solve this problem, the authors used the mathe­matical models that relate the parameters of the flow and the process. The algorithm for calculating the optimal modes of metallurgical processes includes the following steps: generating initial data, calculating stages and sub-processes, calculating the relationship between the parameters of the flow and the process, determining the technical and economic indicators, and solving the optimization problem. The optimization problem is to determine the control actions for the process by finding the extremum of the required criterion, subject to constraints on the parameters of the final product and the conditions of material and heat balances. The problem is solved using nonlinear programming and the generalized reduced gradient method. Using this method, optimal modes of energy- and resource-saving technologies were developed for a new continuous metallurgical process: obtaining metal from pig iron and rolling scale, direct reduction of metal from dusty ores and iron-containing technogenic materials without agglomeration, obtaining manganese alloys from carbonate and oxide ores, processing titanium-magnetite concentrates, and determining the optimal parameters for the processes of nickel reduction from nickel concentrate and vanadium reduction from converter vanadium slag, which ensure maximum metal extraction.

The use of universal existing physical and mathematical models is most expedient in cases where it is technically difficult or impossible to measure a parameter using a sensor. Such parameters include temperature stresses of the working rolls. The article presents a method for calculating the temperature stresses that occur in working rolls of reversing hot rolling plate mills by improving the existing mathematical model for cold rolling mills, which is based on analytical solution of the equations of elasticity and thermal conductivity, assuming that the temperature field of the roll is axisymmetric. A special feature of this analytical solution is that it is not possible to predetermine the graph of the surface temperature change of the rolls that are cooled from the outside, because it is a complex function of the non-stationary technological factors of rolling. Therefore, only the function graph is known in advance, which is set in the form of a continuous angled line obtained from the results of measuring the surface temperature of the working roll. The study is based on the specified improved numerical-analytical model and equations for calculating temperature stresses for a specific layer of the working roll of an operating hot rolling mill in a cross-section, taking into account its design features and the physical and mechanical parameters of its material. The results of a computational experiment for calculating temperature stresses using the improved method demonstrate its adaptation for a reversing hot rolling plate mill. When implementing this experiment to assess the accuracy of determining temperature stresses in the roll’s cross-section, the negative impact of the existing cooling process on durability of the working rolls’ surface layer is shown.