Theory and Practice of Metallurgy

Thermodynamic equilibrium of high-carbon ferromanganese smelting

M. M. Gasik — 2026-04-18

The goal of this study is to carry our detailed thermodynamic analysis of FeMn fluxless smelting process in submerged arc furnaces (SAF) using realistic plant data and compare the calculation results with industrial outcomes. Modern thermodynamic databases FactSAGE was deployed to assess equilibria inside separate phases and between them at 1400-1800°C for two FeMn78 alloys with different phosphorus content. Phases (metal, slag and gas) compositions were calculated with metal recovery value for manganese as well as through-recovery of manganese in both working slag and metal. It was found that temperature of the process 1500-1525°C predicts maximal recovery of manganese into the alloy. The outcomes allowed combination of blended manganese agglomerates, ores, return tails to be efficiently composed and converted into materials streams, which can be fed into the thermodynamic calculations. Such approach allows flexibility to optimize different scenarios in high-carbon ferromanganese fluxless smelting. The correlation of the calculations with industrial plant outcomes was found to be very good. The method gives a good basis to check behavior of different components and elements in the furnace, distribution of them between the phases (gas, metal, slag) and identify the pathways for improvement of the process leading to higher yield and quality. With the same thermodynamic database parameter similar approach can be used for other manganese ferroalloys.

Effect of deformation degree during drawing out on the quality of heavy-duty hook forgings

K. D. Kolisnyk — 2026-03-30

This study investigates the influence of the degree of deformation during the drawing out forging operation on the distribution pattern of plastic strain in billets intended for manufacturing high-capacity lifting hooks. The primary objective is to determine the optimal deformation degree that enhances the uniformity of plastic strain distribution across the forging's cross-section. The research was conducted using numerical modeling of the sequential upsetting and drawing out processes, accounting for the continuity of the technological cycle. Drawing out was performed using the "ring" method (circumferential rotation) with a rotation angle of 15° and a relative feed of 0.5. Three deformation degrees per pass were analyzed: 10%, 15%, and 20%. To quantitatively assess strain uniformity, the nonuniformity coefficient C_n was employed, defined as the ratio of equivalent strain values at control points to the maximum equivalent strain within the cross-section. It was established that increasing the deformation degree from 10% to 20% raises the level of accumulated plastic strain and improves its uniformity across the cross-section. The most uniform strain distribution was achieved at a deformation degree of 20%, where the minimum nonuniformity coefficient value was 0.54. This indicates a 46% reduction in strain nonuniformity (since C_n=0.54 corresponds to nonuniformity reduced to 54% of the reference maximum difference). The obtained results can be applied in the development of rational technological regimes for forging high-capacity lifting hooks with enhanced requirements for quality and reliability.

Development of the technology for manufacturing the bracket for mounting the reducer of the metropolitane cars

S. V. Biriukov — 2026-03-30

This article discusses the developed technology for manufacturing a gearbox mounting bracket used on rolling stock in domestic metro systems. The article also analyses the design of this bracket and the malfunctions that may occur during operation. The specific nature of metro rolling stock operation, characterised by high traffic intensity, frequent acceleration and braking cycles, and significant dynamic loads, places increased demands on the reliability of each structural element of its running gear. Since a significant part of the bogie parts are manufactured using metal pressure processing methods, the issue of improving the quality of stamped forgings becomes a relevant technical task that affects the safety of passenger transport and the accident-free operation of vehicles. This article analyses other works related to improving the mechanical characteristics of products and increasing their quality, which depend on the parameters and methods of their production. The traditional forging technology discussed above usually involves a multi-stage process that includes the use of rolling grooves for preliminary distribution of metal along the axis of the blank. However, this approach increases the size of the stamping equipment and requires more passes, which leads to higher energy costs and production costs. The authors proposed abandoning the use of a rolling groove, since it is possible to manufacture this forging without changing the geometry of the blank before bending. The results of this work can be used by technologists and engineers in the machine-building industry as one of the promising ways to improve and rationalise the stamping of forgings with similar geometry, since by reducing the number of stamping passes, it is possible to reduce the cost of production and manufacture of dies without significantly affecting the stress-strain state of the resulting forging. The expediency of using computer modelling in the design of production technology is also indicated, as it allows all stages of production to be investigated without significant financial costs and ways to improve and rationalise technological operations to be identified, which will have an impact on improving the quality of manufactured products in the future.

Modeling of the deformed state of the screen box of a heavily loaded vibratory machine

D. V. Popolov — 2026-03-30

The paper addresses the problem of improving the technical and economic efficiency of heavily loaded vibratory machines through optimization of the load-bearing frame of the screen box. The main elements providing the spatial stiffness of the box structure are tubular transverse tie-beams, which operate under conditions of intensive cyclic bending loads. Analysis of the available literature indicates that these elements belong to the most highly loaded and vulnerable structural components, for which fatigue failure is the dominant failure mechanism. The traditional approach to increasing the strength of structural elements, namely, enlarging the cross-sectional area, leads to an increase in the mass of the screen box and the associated inertial loads, which adversely affects the dynamic characteristics of the vibratory machine.

The objective of this study was to improve the structural efficiency of the screen box of a vibratory machine by optimizing the geometry of the tie-beams using a rational material distribution along the length of the element. An approach is proposed that involves varying the outer diameter of the tubular tie-beam according to a parabolic law while maintaining a constant inner diameter. Such an approach makes it possible to reduce the beam mass in regions of low bending moments while simultaneously maintaining or increasing stiffness in the most heavily loaded sections. To evaluate the effectiveness of the proposed solution, a series of numerical experiments was carried out using the finite element method. The simulations included calculations of axial compression, bending under transverse inertial loading, determination of the first natural frequency, and estimation of the critical buckling load for tie-beams with both baseline and parabolic profiles. The obtained results demonstrate that the use of a parabolic profile makes it possible to reduce the mass of the tie-beam by 41%, while the transverse acceleration corresponding to the onset of yielding increases by 55%, and the first natural frequency increases by 18%. Stress distribution maps indicate a more uniform loading of the material in the tie-beam with the parabolic profile. The deformed state of the screen box was also modeled using both the baseline and the optimized tie-beams. The results show that the change in beam geometry has virtually no effect on the dynamic characteristics of the box. The first natural frequency of the structure changes only slightly, while the deformation pattern and the maximum displacement amplitude remain practically unchanged. The obtained results confirm the prospects of applying variable-section tie-beams for improving the energy efficiency and reliability of vibratory machines.

Heat balance of billets during hot extrusion of nickel alloy pipes

M. I. Medvediev — 2026-03-30

Annotation. Among the problems encountered in the production of nickel-based alloy pipes by hot extrusion sleeves on horizontal hydraulic presses, one of the main ones is the high level of product surface defects. To reduce rejects on this basis, it is important to understand the changes in the temperature field of the pipe billet throughout the entire technological process, since this factor is the key to the formation of surface defects in such pipes. The purpose of the work is to establish the regularities of temperature changes in nickel alloy pipe billets at the main stages of pipe production, which are made by extrusion on presses with a force of 16.0 MN and 31.5 MN with the use of glass lubricants. Methodology. The work was performed based on the results of a systematic analysis of the main technological stages of the actual process of producing hot-extruded pipes made of nickel alloy 602CA on presses with a force of 16.0 MN and 31.5 MN. The selected production stages include: transporting the billet (liner) from the induction heater to the glass-filled table, applying glass-filled material to the billet surface, transporting the billet with glass-filled material to the press, holding the billet in a container before extrusion, and extrusion in the container. The calculation of the stepwise temperature loss by the billet was performed using known and own empirical equations obtained from the results of thermography of the billets. The chemical composition of the billets was determined using an Elvax plus spectrometer. The temperature of the outer surface of the workpiece was measured using chromium-aluminium thermocouples complete with an electronic potentiometer. Results. It was found that the total change in the temperature of the sleeves during the cooling process during auxiliary operations on presses with a force of 16.0 MN and 31.5 MN at the same initial heating temperature of the workpieces is inversely proportional to their wall thickness. At the same time, this dependence is almost linear in the range of 40...120 mm wall thickness of the sleeves and 1050...1250 °C heating temperatures of the workpiece. Scientific novelty. For the first time, a methodology for calculating the temperature of the sleeves at the main stages of their preparation for the extrusion process has been developed. Practical utility. The use of the developed methodology for calculating the temperature of the liner allows for a reasonable choice of glass lubricant for the initial technological operations of extrusion on presses with a force of 16.0 MN and 31.5 MN using glass lubricant, which in turn contributes to improving the surface quality of pressed pipes, reducing the level of pipe rejects and reducing the volume of their the volume of their further mechanical processing.

Improvement of pig iron production technology by using the useful properties of the potential of secondary resources of raw materials and fuels

A. P. Mishalkin — 2026-03-30

Abstract. The scientific and technical relevance of the study lies in determining the directions for improving the ways of using the useful properties of secondary resources in order to intensify the blast furnace process, increase its energy efficiency and reduce pollutant emissions. At the same time, economic efficiency is achieved by reducing the cost of purchasing primary raw materials and reducing waste generation, which corresponds to modern concepts of sustainable development on the way to "green" metallurgy. Purpose of the study. Scientific and practical substantiation of directions for improving the technology of pig iron production through the use of useful properties of secondary resources of raw materials and fuels that have a man-made origin. It is aimed at increasing the level of energy efficiency and improving the slag regime of the blast furnace process, reducing the man-made load on the environment of industrially developed regions of Ukraine. To achieve this goal, the following theoretical and practical tasks will be solved in the study:

The analysis of the current state of use of secondary resources of mineral raw materials and fuel in blast furnace production in the conditions of world and domestic metallurgical enterprises has been carried out.
The physicochemical properties of the most common types of secondary resources (man-made wastes of metallurgical origin: dust, sludge, scale, production of metallurgical lime: fractions from gas cleaning devices and heat treatment products of waste of plant origin, which are sources of pyrocarbon) have been investigated. Further - determination of the spectrum of their probable purpose, impact on the features and indicators of the blast furnace process, as well as justification of rational ways of their preparation and use.
Rational shares of substitution of traditional raw materials and fuels with secondary materials in the blast furnace process are substantiated, the use of which will not reduce the quality of pig iron and will not increase the specific consumption of coke. Their influence on physicochemical and heat-gas-dynamic processes, which is reflected in the characteristic zones of the blast furnace, has been studied.
The optimal technological schemes and recommendations for the methods of introduction and rational specific consumption of innovative materials based on man-made wastes have been determined, which will ensure the maximum level of use of their useful properties in the material and thermal balances of the blast furnace process.
The technological and environmental advantages of introducing into the blast furnace process a monomaterial, the composition, physicochemical features and spectrum of purpose of which are formed by heat treatment of a mixture of man-made industrial waste, are evaluated and their prospects as a substitute for the corresponding part of pulverized coal fuel (PCF) and fluxes are determined.

Research methods. When conducting a comprehensive study, the following methods will be used:

- analysis and generalization of materials of scientific and technical literature and patent sources, coordination of their results in accordance with modern trends and the best results of the practice of using secondary resources in blast furnace production;

- physicochemical methods of analysis chemical, thermogravimetric, to determine the composition, structure, metallurgical value, probable spectrum of purpose and reactivity of secondary resources of materials - substitutes for iron ore raw materials, coke and pulverized coal fuel (PCF);

- thermodynamic forecasting and kinetic modeling of the behavior of experimental materials of secondary origin under the conditions of their heat treatment to assess the influence of their properties on the course of physical and chemical processes and transformations to the thermal and gas-dynamic regime of the blast furnace.

The expected results of the study should also include:

- development of scientifically grounded recommendations for the effective use of useful properties of the initial potentials of secondary resources of raw materials and fuel in blast furnace production;

- establishment of quantitative ratios regarding rational levels of substitution of traditional fuel and raw materials with secondary ones, without reducing the productivity of the furnace and the quality of pig iron while reducing the specific consumption of lime and PCF;

- development of a method for the implementation of a complex technological scheme for the preparation, heat treatment of experimental mixtures based on components of mineral raw materials and fuel, followed by the use of an innovative product in the conditions of blast furnace production of pig iron;

Scientific novelty of the work. For the first time, systematically, on the basis of the results of an analytical and practical study, the energy efficiency of production and use in the blast furnace process of a two-component monomaterial based on dispersed waste from the production of lime and materials – waste of plant origin, obtained by implementing the effect of their pyrolysis under conditions of joint heat treatment of the initial mixture layer, was substantiated, tested on high-temperature models, poured thermal, in an inclined rotary drum-type furnace. For the first time, a resource-efficient and results-efficient approach has been used to assess the efficiency of the use of materials based on secondary resources of metallurgical and plant origin, based on an integrated combination of the results of thermodynamic forecasting, physical modeling and taking into account the provisions of the exergical methodology for assessing the energy efficiency of the objects of study. Methodological bases have been developed for the selection of rational schemes for the introduction of complex materials based on secondary materials into the blast furnace charge and in the air blast flow to stabilize gas-dynamic conditions in the charge layer, intensify recovery processes with a decrease in the specific consumption of coke per ton of liquid pig iron. The regularities of the influence of the composition and dispersion of secondary resources on the gas-dynamic and thermal parameters of blast furnace smelting have been revealed, which makes it possible to increase the accuracy of predicting the furnace course. It has been proved that the use of materials based on secondary resources of mineral raw materials and fuels can provide the effects of increasing the energy efficiency of pig iron production and reducing the environmental burden, which meets the requirements of sustainable development and the concept of "green metallurgy".

Increasing the corrosion resistance of ferrosilide in hot sulfuric acid by alloying with chromium, nickel and molybdenum

Ye. M. Siharov — 2026-03-30

The corrosion resistance of ferrosilides of the Fe-Si-Cr-Ni-Mo-Mn system in concentrated sulfuric acid in the temperature range of 25-200°C was investigated. The corrosion rate was calculated based on electrochemical parameters using passivation and temperature dependence models of the Arrhenius type. It was confirmed that the main factor determining corrosion resistance is the silicon content. The existence of a critical Si content threshold was shown, upon reaching which a continuous passive SiO₂ film is formed, which provides a reduction in the corrosion rate by 1-2 orders of magnitude. Characteristic temperature ranges of the corrosion process were identified: stable passivation (25-80°C), transitional regime (80-150°C) and degradation of the passive state (150-200°C). It has been shown that Cr and Mo in Fe-Si alloys enhance the stability of the passivated state, particularly at high sulfuric acid temperatures, whereas Ni primarily affects the electrochemical characteristics, and Mn reduces the effectiveness of passivation. The effectiveness of adding chromium to Fe-Si alloys increases proportionally with the Si content; molybdenum stabilizes passivation at acid temperatures above 150°C and reduces the rate of localized corrosion; nickel is not a determining factor at high acid temperatures. The influence of operational factors (turbulence, erosion, impurities) on the corrosion rate has been determined. The expected corrosion rates for the studied alloys in sulfuric acid have been calculated, taking into account industrial operating conditions. The experimental data obtained can be used to develop new corrosion-resistant materials and optimize the composition of Fe-Si alloys for operation in high-temperature aggressive environments of concentrated sulfuric acid.

Prospects for recycling leather industry waste as a source of chromium-containing raw materials: physicochemical analysis of the Fe–Cr–P–O system

D. O. Stepanenko — 2026-03-30

The paper considers thermodynamic and physicochemical regularities of phosphorus behavior in multicomponent systems of Fe–Cr–P, Fe–Cr, Fe–P, Cr–P and Fe–Cr–P–O when using chromium-containing man-made raw materials, in particular substandard ores and leather industry wastes. The analysis of the current state of the raw material base of chromium in Ukraine is carried out and the expediency of attracting alternative sources of chromium-containing raw materials is substantiated. The literature data on phase equilibrium, thermodynamic properties and features of the formation of phosphide and oxide-phosphate phases in these systems is summarized. It has been established that the main problem of the use of man-made raw materials is the increased content of phosphorus, which negatively affects the properties of the metal. It is shown that solid-phase reduction creates favorable conditions for controlling the distribution of phosphorus between the metal and slag phases. The influence of temperature, charge composition and interatomic interaction on the stability of phosphide phases and the efficiency of dephosphorization has been determined. Particular attention is paid to the role of the magnetic state of iron and the conditions for the formation of solid solutions and intermetallics in the Fe–Cr–P system.

The results obtained can be used to develop energy-efficient technologies for the processing of chromium-containing waste and substandard ores in order to reduce import dependence and increase the environmental safety of metallurgical production. The purpose of the work is to study the thermodynamic and physicochemical patterns of phosphorus behavior in the Fe–Cr–P, Fe–Cr, Fe–P, Cr–P and Fe–Cr–P–O systems when using complex chromium-containing raw materials (substandard ores and leather industry wastes), as well as to substantiate the possibility of controlled phosphorus removal in order to improve the quality of the obtained metals and alloys. Research methodology: A systematic analysis of the scientific and technical literature on phase equilibrium and thermodynamic properties of Fe–Cr–P, Fe–Cr, Fe–P, Cr–P, Fe–Cr–P–O systems was carried out. composition of the charge and reducing medium for the distribution of phosphorus between phases. Scientific novelty: The relationship between the parameters of the interatomic interaction (ZY, d, tgα, ρl) and the thermodynamic stability of phosphide phases has been established. Practical significance: The expediency of using leather industry waste as an alternative source of chromium for metallurgy has been substantiated. Approaches to reducing the phosphorus content in the processing of complex raw materials, which allows to improve the quality of steel and ferroalloys, have been proposed. The optimal temperature and thermodynamic conditions for the implementation of dephosphorization processes have been determined. The results can be used in the development of energy-efficient technologies for solid-phase recovery and recycling of waste. It helps to reduce Ukraine's import dependence on chromium-containing raw materials and increase the environmental safety of production.

High-entropy alloys. A new concept for the design of innovative structural materials

L.V. Kamkina — 2026-03-30

Modern technologies require state-of-the-art materials that meet their conditions, regardless of operating conditions. Alloys with high entropy can replace traditional materials, work under impacts, dynamic loads, elevated temperatures, etc. These alloys are used for the manufacture of tools, molds, dies, mold casting in parts that require high strength, resistance to oxidation and wear, can also be used in environments with high corrosion resistance parameters (plumbing, marine conditions), in aggressive conditions and in the chemical industry. High entropy alloys are quite easy to investigate and control, and can be obtained by the same methods as traditional alloys, such as: casting, rapid melt quenching, film sputtering, electrolysis, and mechanical alloying.

Electroslag remelting (ESD) can greatly improve the purity, hardening structure, and transverse mechanical properties of steel. However, the increasing demands on the mechanical properties of steel are prompting metallurgists to make more efforts to eliminate defects in steel microstructures such as shrinkage and segregation. The combination of directional crystallization technology with electroslag melting technology effectively eliminates macrosegregation in the cast ingot through a shallow molten metal bath controlled by directional crystallization. Increasing the strength of alloys can be achieved either by alloying a solid solution (elements in the internodes) or by isolating the solidification phases or artificially introducing microparticles. Curing phases (carbides, nitrides, carbonitrides, intermetals) can be endogenous (formed from elements introduced into the melt in a liquid state or during its solidification and subsequent cooling) or exogenous (usually introduced into the melt just before crystallization begins, and there is also an increase in size and deterioration in the distribution of solidification phases.