The paper provides a brief description of the metallurgical process at PJSC Severstal, demonstrates the practical experience of reducing the consumption of dry skip coke from 415 to 350 kg/t of pig iron over the period 2014 – 2024, a decrease of 15.7 abs. %, and identifies the potential for further reduction of solid fuel consumption in blast furnace smelting. Research directions and tasks were formulated to adjust the technology in order to reduce the specific consumption of solid carbon fuel (including by replacing coke and its solid carbon substitutes with injected natural gas), improve the metallurgical properties of iron ore charges, and determine the optimal level of secondary resources use in the charge. The authors presented the results of laboratory studies of the processes of liquid phase formation during the melting of ordinary (SiO₂ content 4.9 – 7.2 %) and low-silica (SiO₂ content 2.8 – 3.0 %) pellets. The temperature level of the softening zone, complete loss of gas permeability of the iron ore layer, and drip flow of primary slag melts in low-silica pellets increases by 45 – 50 °C compared to ordinary pellets. The article considers the production results of using 3 – 5 mm iron ore screening directly in the blast furnace process (200,000 tons, or 22.3 kg/t of pig iron in 2017). Based on the results of the studies of coke samples taken from operating blast furnaces at a depth of 10 – 12 m from the charge level and in the tuyere zones, it was concluded that it is possible to use solid fuel with increased reactivity in conditions of iron smelting with a low alkali load (reduced from 3.2 kg/t of pig iron to 2.8 kg/t of pig iron). Based on laboratory studies, the effect of various compositions of reducing gases with variable hydrogen content on the reduction process of sinter and pellets was established. The reduction factor (R_f, %) increases by 2.5 – 3.0 % for every 5.0 % increase in hydrogen content in the gas mixture. The indicator “carbon consumption during ironmaking in blast furnaces” was determined, which allows to assess the real efficiency of blast furnace smelting from the point of view of the climate agenda, and the results of reducing this indicator by 12.4 kg/t of iron (3.0 rel. %) for the period of 2014 – 2023 were presented. The authors formulated the directions for the development of PJSC Severstal first processing stage, including the gradual abandonment of the sintering stage with an increase in the share of pellets in the blast furnace charge to 90 %, a reduction in consumption of coke in the blast furnace to 270 kg/t of pig iron, and an increase in the consumption of gas-based coke substitute (natural gas) to 300 m³/t of pig iron.

Electric arc furnace (EAF) dust is a complex multi-component waste of metallurgical industry, containing such valuable elements as iron and zinc. However, in addition to iron and zinc, EAF dust can be contaminated with various impurities, in particular chlorine, which complicates its subsequent processing. The authors investigated the possibility of chlorine removal from EAF dust by static washing with water. The main parameters are washing time, temperature mode, solid-to-liquid ratio, as well as the possibility of reuse of the waste water after washing. During the research, the optimal values of these parameters were determined: washing time of 1 h, solid to liquid ratio of 1:5 – 1:10 and temperature in the range of 20 – 40 °C. The main chlorine-containing phases in the dust are NaCl and KCl, which is confirmed by the transition of Na⁺, K⁺ and Cl^– ions into solution. The maximum transition of chlorine reaches 98 %, while its content in the dust decreases from 2 % to less than 0.2 %. Significant losses of zinc and other valuable elements were not recorded. The main chlorine-containing phase in the dust under study is NaCl, since the presence of Na in dry residual portions was not detected. The poorly soluble compounds PbOHCl and Pb₂CO₃Cl₂ are absent. To a lesser extent, chlorine is in the form of KCl, which is confirmed by the presence of K in the dry residual portion. It should also be noted that calcium actively transfers, which may indicate the presence of calcium hydroxide Ca(OH)₂ in the dust. Additionally, the possibility of using waste water for repeated washing was established, which makes the method ecologically and economically feasible. The results obtained confirm the efficiency and practical applicability of the method of preliminary cleaning of EAF dust from chlorine by water washing before subsequent processing.

Low-alloyed low-carbon steels are widely used in the manufacture of objects for various purposes due to the excellent combination of their service and technological properties. The desire of manufacturers to use material resources in the most economical way determines the relevance of searching for optimal chemical compositions and corresponding technological modes. The article presents the results of a study of hot-rolled low-carbon steels microalloyed with Nb, Ti, V and Mo in various combinations and concentrations produced in laboratory conditions. Optical and electron microscopy methods were used to study the structural state. An analysis was made of the influence of the final stage of thermo-deformation treatment and the microalloying system on the structural state, including formation of nanosized phase precipitates of different types, implementation of strengthening mechanisms and, accordingly, the mechanical properties of the rolled products. Different combinations of the values ​​of temperature of hot rolling end, the cooling rate to the coiling temperature, and the coiling temperature with the microalloying system lead to implementation of different strengthening mechanisms. At high cooling rates in steels with molybdenum, the microstructure of bainitic ferrite is formed, but interphase precipitates do not have time to form. For steels microalloyed with vanadium, these rates do not prevent the precipitation of carbides by the interphase mechanism, since due to the small size vanadium atom has a higher diffusion mobility compared to niobium. The amount of interphase precipitates in Nb – Ti microalloyed steels is less than in steels with molybdenum. The amount of precipitates formed in austenite is also greater in the case of complex Nb – Ti – V – Mo microalloying. Elevated temperatures of the rolling end and coiling contribute to implementation of the precipitation harde­ning mechanism due to interphase precipitates. At too low values ​​of these temperatures, the diffusion mobility of atoms during cooling of the wound roll is low, which limits the formation of nanosized precipitates in an amount sufficient for effective precipitation hardening.

The Baikov Institute of Metallurgy and Materials Science of the Russian Academy of Sciences (IMET RAS) developed an autoclave lime-alkali desiliconization method for titanium concentrates from the Pyzhemskoye and Yaregskoye deposits (Sredny and Yuzhny Timan, Komi Republic). The ores of these deposits are quartz-leucoxene and quartz-ilmenite-leucoxene sandstones. The formation of the titanium component of these deposits is associated with the leucoxenization of ilmenite. The geological process involved the removal of iron from the parent titanium minerals and the filling of the resulting voids with quartz through its crystallization from hydrothermal solutions. This resulted in the ultra-dispersed size of inclusions (1 – 20 µm) of SiO₂ and its structure characterized by weaker (unsaturated) Si – O (Si) bonds. As a result, a high degree of desiliconization of leucoxene and ilmenite concentrates is achieved at 220 °C under autoclave conditions due to the almost complete removal of quartz from titanium grains. At the same time, hydrothermal synthesis of calcium metasilicate hydrates (tobermarite, xonotlite) takes place, the morphological properties of which depend on the conditions of autoclave leaching. In the autoclave, during a relatively short duration of the process, at a ratio of CaO/SiO₂ = 0.7 – 1.0, calcium silicate with a needle-like habit is obtained, which forms predominantly radially radiant sinters. Upon subsequent calcination, their complete dehydration occurs with the crystallization of β-wollastonite (CaSiO₃) increasingly gaining practical application in various fields, including science-intensive ones.

The work continues a series of two articles devoted to the study of cold resistance of new cast Cr – Mn – Ni – Mo – N steel including compa­rison with cold resistance of traditional Cr – Ni cast steel 12Kh18N10Т–CC (CC – centrifugally cast) published earlier in this journal. The mecha­nical properties of cast steels 05Kh21AG15N8MFL and 12Kh18N10Т–CC were studied in tensile tests at low temperatures. In particular, microstructures, engineering tensile curves at different temperatures were considered, microhardness measurements were carried out, and fractographic studies were conducted. The authors compared the results with the calculated and experimental estimates of austenite stability of the studied steels during cooling and deformation, with the results of impact bending tests. Using various methods that complement each other, it was revealed that under simultaneous static and impact loading: new austenitic cast steel alloyed with nitrogen retains austenite stability; in 12Kh18N10Т–CC steel, deformation-induced martensite is formed both under tension and under impact bending. The effect of deformation-induced martensite formation in this steel on the temperature dependence of mechanical properties was estimated. The research results were considered taking into account the available literary data including those on the mechanisms of deformation-induced martensite formation in metastable austenitic steels, the effect on the amount of deformation-induced martensite and the type of martensite depending on a decrease in test temperature, deformation rates under tension and impact bending, the relationship between the appearance of deformation-induced martensite and its type with the stacking fault energy level, the effect of deformation-induced martensite on mechanical properties during static and dynamic tests.

The study provides a detailed analysis of the effects of high-speed cooling methods and the use of rapidly cooled charge materials (ferro­alloys, modifiers, alloying additives) on the microstructure and performance properties of ferrous metallurgy alloys, with a particular focus on ductile iron (nodular cast iron). Experimental results demonstrate that precise control of cooling rates within the range of 10⁵ – 10⁶ K/s enables the targeted formation of fine-grained and homogeneous structures with enhanced strength, impact toughness, and wear resistance. It was established that the use of rapidly cooled master alloys, such as Cu – Mg, not only increases magnesium recovery to 50 – 60 % but also significantly improves modification kinetics: the duration of the exothermic reaction is reduced by 1.5 – 2.0 times, while the formation of nodular graphite becomes more stable and reproducible. The highest efficiency is achieved at cooling rates of 800 – 1650 °C/min, which promotes phase refinement, reduces segregation, and increases tensile strength by 15 – 20 % compared to conventional methods. Special attention is given to ferroaluminum modifiers (25 – 33 % Al), for which the possibility of controlling the size and distribution of structural components solely by adjusting the cooling rate – without subsequent heat treatment – was confirmed. This opens the prospects for energy-efficient technologies. The study demonstrates that rapidly cooled materials not only enhance mechanical properties but also offer technological advantages: reduced consumption of alloying elements, improved process repeatability, and environmental benefits due to lower emissions. The results hold significant practical potential for developing new generations of alloys with tailored properties, combining high performance, resource efficiency, and compliance with environmental standards. Thus, the application of high-speed cooling techniques and rapidly cooled charge materials represents a promising direction in modern metallurgy, enabling optimization of both structural and process parameters in production.

The oscillating-cup method is the most common method for studying the metallic melts viscosity at high temperatures. However, the data obtained by different authors using this method may differ by several tens of percent. The reasons for this lie in the features of the method which lead to the influence of experimental conditions on the measurement results. In this paper, the boundary conditions influence at the melt upper boundary and processes of preliminary sample preparation on the viscosity measurements results is considered. It is shown that under certain experimental conditions, anomalies of a methodological nature can occur on polytherms. The considered features of the experiment are a consequence of film effects, wetting phenomena and irreversible processes in the melt-crucible system. Methodological processes are proposed that allow us to identify and eliminate their influence on the viscometry results. Film effects are caused by changes in the melt surface condition as a result of formation of a viscous film. To eliminate them, viscosity measurements should be carried out using different boundary conditions at the melt upper boundary. The wetting phenomena influence is caused by the meniscus formation at the upper boundary of the melt. When measuring viscosity in crucibles with a lid on the melt, the wetting influence can be eliminated by selecting the modes of preliminary remelting or by selecting the lid mass. Irreversible processes in the melt-crucible system are associated with the crucible gradual destruction when the sample is cooled below the crystallization temperature due to the high adhesion of the alloy to the crucible walls and differences in their thermal expansion coefficients. To eliminate them, the authors proposed a mode of the sample remelting with overheating of the melt to the maximum temperature expected in the subsequent measurement cycle and cooling to a temperature 100 ºС below its solidification temperature.

The authors consider the influence of various processing technological parameters (grinding wheel rotation speed, part rotation speed and longitudinal feed speed) on roughness of the surface restored by induction baking followed by rolling of the marine engine sleeve. These parameters play a key role in ensuring precision processing and achieving minimal roughness, which, in turn, affects the durability and efficiency of the engine. The advantages of impregnated abrasive wheels, which reduce tool wear and improve processing accuracy, were analyzed. The described technologies for restoring parts, such as induction baking and rolling, increase wear resistance and fatigue strength. Importance of precise adhe­rence to processing modes to prevent defects was emphasized. The presented methods improve the quality of the parts, their performance and service life, which is especially important in mechanical engineering. During internal abrasive processing of restored engine sleeves, application of a cutting fluid intensifies the adhesive interaction between nickel- and chromium-based materials and the abrasive grains, resulting in reduced processing efficiency. The impregnated wheels reduce chip sticking, increase self-cleaning, prolong tool life, and lower the temperature in the cutting area. The authors carried out the experiments on processing the internal surfaces of the restored engine sleeves by three processing methods. The proposed improved method for impregnating abrasive wheels ensures an even distribution of the impregnation solution. Reduction of roughness of the treated surface and reduction in wheel loading were experimentally confirmed. It was found that reducing the part rotation speed and the longitudinal feed speed increases the roughness, but the proposed method allows it to be minimized. Influence of rotation speeds of the part and the abrasive wheel on the surface roughness during processing was investigated. Increasing the part speed increases the grain contact length, degrading the surface quality. Increasing the wheel speed, on the contrary, reduces the roughness. The experiments confirmed that impregnated wheels reduce roughness during internal processing of restored sleeves by 1.5 – 1.8 times.

The article presents an integrated approach to the development and implementation of information modeling systems (IMS) designed to control blast furnace smelting technology. The main attention is paid to the creation of mathematical models of thermal, gas-dynamic and slag modes which allow more accurate prediction of the blast furnace behavior under conditions of changing raw material properties and combined blast parameters. The presented results demonstrate that the use of a modular architecture for building information systems and modern computing technologies allows expanding the set of process parameters for assessing the progress of blast furnace smelting, increasing the efficiency of monitoring production processes and reducing the costs of developing and maintaining software for information systems due to their automation. It is shown that the use of a modular architecture and microservice technologies provides flexibility, scalability and the ability to adapt software solutions to specific production tasks. The article presents the results of developing software for subsystems for calculating thermal and gas-dynamic modes, as well as predicting the silicon content in cast iron and the properties of the final slag. Practical implementation is carried out using modern .NET, PostgreSQL, Docker and DevOps tools. A comparative analysis of the subsystems’ operation confirmed their efficiency when integrated with the automated process control system and production databases. The tests were conducted on real industrial data. The obtained results indicate the high practical significance of implementation of the integrated management system for ensuring the stability and efficiency of blast furnace smelting in the context of digital transformation of metallurgical production.

Mathematical model of the shrinkage process in a continuously cast slab during its cooling and solidification is proposed. The model is based on solution of the equation of non-stationary thermal conductivity and provisions of the theory of a quasi-equilibrium two-phase zone. Unlike previously proposed models of the slab cooling and solidification process, the proposed one takes into account the dependence of thermal properties of the steel on temperature, as well as such features as chemical composition of the cast steel, geometric shape of the slab cross-section and the process parameters of casting rate and intensity of slab cooling in the secondary cooling zone. The model implements the solution of the heat conductivity equation using the finite difference method, approximation of partial derivatives is performed according to an explicit scheme. During modeling, the temperature field is calculated in the computational domain, which is a quarter of the slab cross-section. In this case, the boundary conditions in the mold and cooling sections of the secondary cooling zone of continuous casting machine are taken into account. The model also implements calculation of the total shrinkage in the slab from the moment of crystallization and also can be used to calculate the shrinkage cavity depth formed in the slab after casting. The model adequacy is confirmed by verification performed by comparing the modeling data with experimental data on the shrinkage cavity depth. Dependence of the modeling accuracy on the number of computational grid nodes is also revealed. The presented model allows calculating the shrinkage cavity depth and developing recommendations for adjusting the mold taper and the parameters of continuous casting machine roller guide depending on the amount of metal shrinkage during cooling and solidification of continuously cast slabs.

The authors propose to use the generalized conductivity theory (GCT) for mathematical modeling of electrical conductivity of metallic melts with eutectic and monotectic interaction of components. The main GCT approaches are considered and analyzed: the method of transition to unit cell and the effective medium method, which allow describing the properties of heterogeneous liquid metallic systems. The paper presents a mathematical formulation of the problem of calculating the effective coefficients of electrical conductivity from the known values ​​of the specified parameters of the initial components and their concentrations. An example of calculating the specific electrical resistance of Pb-Bi melt with eutectic interaction of the components is given. The calculation was carried out using the method of transition to the elementary cell of Rayleigh: a model of a structure with interpenetrating components, a model of a structure with isolated inclusions; and the effective medium method. The results of calculations for these models are compared with experimental data on the specific electrical resistance of liquid Pb – Bi alloys in a wide range of temperatures and concentrations. All three approaches to estimating the specific electrical resistance of Pb – Bi melts showed the results close to the experimental data. The closest values ​​were demonstrated by the model of a structure with interpenetrating components, for which the standard deviation of the calculated values ​​from the experimental ones was less than 4 %. The authors substantiated that the use of GCT for calculating the effective coefficients of melts’ electrical conductivity is advisable at the initial stages of developing new metallic materials with specified properties, especially in cases where direct experiments are difficult. This approach allows for a significant reduction in time and financial costs of synthesizing samples and experimentally studying their physicochemical characteristics.

Intensive development of the constructional industry for expansion of housing and industrial stock requires an increase in the production of small–section rebars with a linear meter weight of 6 - 8 kg. Such rebars are produced on small-section and small-section wire mills. An increase in the production of small-section building rebars can be implemented in two directions: construction of new high-performance rolling mills; intensification of the work of existing mills due to identification of hidden reserves (“bottlenecks”) and, taking this into account, modernization of equipment and technology. The second direction is less financially costly and requires significantly less time to implement. However, a sound analysis of the constraints is required for making the right decision to improve the existing production. To solve this problem, the authors propose a methodology based on the principles of a clock approach and the necessary calculation formulas which, using the example of a small-section workshop, show the sequence of search and analysis of “bottlenecks”. The paper analyzes the organization of production processes at the areas of a small-section mill and considers in detail two alternative schemes for organizing material flows at the baling area. The actual material presented in tabular forms characterizes the work of the areas of a small-section workshop by cycles and productivity by rebars for different schemes of material flows. The main limiting factor in the small-section shop under study is the baling area. The authors propose organizational and technical measures to improve the organization of material flows and automation of baling lines, evaluate the effectiveness of design solutions and the payback period for investments.