Theory and Practice of Metallurgy

Production of chromium concentrate from press-filtration residue by means of heat treatment

2025-11-12T04:13:36+02:00

The production of leather goods is an important industry that generates significant amounts of waste, including solid residues containing chromium compounds. Solid residues of leather production containing chromium are a valuable source for the production of chromium alloys, in particular chromium-based alloys used in metallurgy, as well as in various industries to create stainless steels and corrosion-resistant materials. The goal is to integrate the process of industrial waste recycling into production, which will reduce not only the environmental footprint but also create materials with high technological properties for further use in various industries. The methodology for producing chromium alloys from the solid residue of leather goods production is a complex and multi-stage process that includes preparation, heat treatment, chromium recovery, alloy manufacturing, and waste disposal. This approach not only reduces the environmental footprint, but also allows for the efficient use of secondary resources to produce high-quality metals and alloys. As a result of such production, significant environmental and economic benefits can be achieved, which will not only reduce costs but also ensure sustainable industrial development with minimal environmental impact. The scientific novelty of this methodology is the integration of modern technologies for processing leather waste to produce high-quality metal alloys that meet the requirements of modern industrial development. The practical significance of this method for the production of chromium alloys from the solid residue of leather products production is to save natural resources, improve the environmental situation, increase economic efficiency and promote sustainable development of both the metallurgical and leather industries. This allows us to make a significant contribution to sustainable economic growth with minimal environmental impact.

Optimizing the chemical composition of the steel of arrow translations to increase the level of physical characteristics of metal products

2025-11-12T04:29:11+02:00

The analysis of regulatory documents on the chemical composition and level of mechanical properties of austenitic high-manganese steel 110G13L for turnouts is performed. Using mathematical methods of statistics, correlation dependencies of the influence of impact toughness values on the strength characteristics of the metal are obtained. It is established that the values of tensile strength σ_b and impact toughness a_k are decisive factors for a set of strength-viscosity properties of castings made of steel 110G13L. The rational composition of the metal is substantiated, taking into account the manganese content (≈12%) and the ratio of manganese to carbon (10.56-13.60) for the production of metal castings of group I according to GOST 7370-98.

Preparation of rolled products for processing at a pipe rolling unit

2025-11-12T04:40:06+02:00

Purpose. The aim of this work is to examine rolling processes with variable deformation modes by transferring part of this deformation from the mill under consideration to the preceding mill, as well as to develop a process for preparing the billet ends by transverse planetary burnishing with idle rolls. Methodology. Using the slip-line method, the forces acting on the idle rolls during transverse planetary burnishing of the billet end, as well as the torque and power of the burnishing process, were determined. The thinning of the wall at the front end of the billet during its preparation by transverse planetary burnishing with idle rolls was analytically established. Findings. One of the main reserves for further increasing productivity, saving metal, and improving geometric dimensions in the production of hot-rolled seamless pipes is the use of variable deformation modes across the wall thickness. Examples of additional operations carried out on various pipe-rolling mills are considered, demonstrating their high efficiency. For the design of a method for preparing the front ends of billets, planetary rolling processes applied in pipe-rolling production were analyzed. Originality. The method of transferring part of the deformation from the main mill to the preceding mill has been further developed, which significantly improves rolling conditions in the main mill and enhances its performance indicators. Practical value. The process of transverse planetary burnishing of billet ends appears highly promising and warrants further research and development. The results of this work can be applied in selecting the most rational method of metal preparation for rolling, taking into account the specific technology of a given pipe-rolling mill.

Influence of physicochemical melt treatment on structure and properties of AK7ch alloy microalloyed with Sr-Sc and Ti-B-Sr complexes

2025-11-12T04:50:36+02:00

Purpose. The aim of research is to determine the features of structure formation and property enhancement in the AK7ch alloy under the influence of microalloying with complex modifiers Sr-Sc and Ti-B-Sr, as well as physicochemical treatment in the liquid state. Methodology. The object of study was the AK7ch alloy of the base composition and microalloyed with Sr-Sc and Ti-B-Sr complexes in both the as-cast state and after hydrogen and thermotemporal melt treatments. Structural formation was investigated using metallographic analysis. The ultimate deformability was determined by an improved method for assessing the limiting deformation degree during rolling of wedge-shaped samples. Corrosion resistance, including general and intergranular corrosion susceptibility, was assessed using standard testing methods. Results. It was found that the combined physicochemical effect of microalloying with Sr-Sc and 20-minute hydrogen melt treatment increased the deformability of the AlSi7 alloy by 60%. Ti-B-Sr addition and 30-minute thermotemporal melt treatment increased deformability by 46% compared to the original as-cast alloy. It was also established that microalloying with Ti-Sr-B and isothermal treatment for 30 minutes significantly enhance the corrosion resistance of the AK7ch alloy. Scientific novelty. The study proves the effectiveness of microalloying with Sr-Sc and Ti–B–Sr complexes in combination with hydrogen and thermotemporal melt treatments for improving the deformability of AK7ch alloy compared to the base composition. The positive effect of such treatments on the alloy’s general corrosion resistance was also confirmed. Practical significance. The research provides effective methods for enhancing the technological deformability and corrosion resistance of AK7ch aluminum alloy through microalloying with Sr–Sc and Ti–B–Sr complexes in combination with hydrogen or thermotemporal melt treatment. The proposed approaches significantly improve the alloy’s structure, which promotes increased corrosion resistance and overall reliability of finished products, especially in critical components used in mechanical engineering, aviation, and transport industries.

Using cold stretching deformation to increase the strength of rebars in coiled product manufacturing technologies

2025-11-12T05:01:25+02:00

Purpose. To analyze the current state-of-the-art reinforcing bar (rebar) production for the construction industry, review existing data on the effects of strain hardening through cold stretching of steel rods, and apply these findings to the development of an effective technology for producing high-strength coiled rebar. Methodology. The research is based on an analytical study of using cold stretching deformation to increase the strength of steel rods. A comparative analysis of known patented technologies for producing 500 N/mm² strength class rebar in coils, particularly those developed in post-Soviet countries, was also conducted. Findings. The study analyzed three primary methods for strengthening rebar: alloying, heat treatment, and cold deformation. Alloying has become less cost-effective due to the high price of ferroalloys. Heat treatment is currently the most widespread method for producing high-strength rebar (grades A500C, A600C, etc.) according to DSTU 3760:2019. Cold deformation, while used globally for over 60 years and historically in the USSR to produce grade A-III_в rebar (equivalent to modern A500), is underutilized in Ukraine. The paper examines the principles of strengthening via cold stretching and reviews patented solutions for its application in coiled rebar production, presenting both positive and negative real-world examples. The necessity of applying stretch deformation to reliably achieve the 500 N/mm² strength class is established. Originality. The originality lies in the proposed technology and equipment for manufacturing cold-deformed coiled rebar. This process uniquely combines cold stretching deformation, which strengthens 100% of the product, with a final mechano-cyclical treatment. This combination not only increases strength but also ensures a high level of ductility in the finished product. Practical value. The implementation of the proposed technology will enable the domestic production of a new product: 500 N/mm² strength class coiled rebar for reinforced concrete. This product is poised to be in high demand and will play a significant role in the post-war reconstruction of Ukraine.

Digital modeling of metamaterials for 3D printing of foundry patterns in the context of transition to on-demand manufacturing

2025-11-12T05:08:12+02:00

In today's conditions of global instability, market fluctuations and variability of consumer needs, manufacturing "on demand" is becoming a promising strategy, supported by innovations in the field of additive manufacturing (3D printing). The purpose of the work is to study the use of the sphereneRHINO program (Spherene Inc., Switzerland) for designing and printing porous structures of foundry models instead of traditional ones made of expanded polystyrene. Methodology: the process of digital design of polymer patterns was analyzed, design was performed in the specified program and pattern samples were printed. Findings. The algorithm and capabilities of the sphereneRHINO program are exemplarily described, samples of cellular material of patterns were obtained, a method of printing them with open pores and transit porosity was developed. The gas permeability of the pattern was used to vacuum the sand mold and the pattern structure, which allowed it to be gasified with molten metal with simultaneous pumping out of gases and to create the effect of casting by vacuum suction. Originality. The foam material, which was not intended for casting patterns, was used to design and print porous patterns with control of density, wall thickness and geometry of printed pores. Practical value: a significant reduction in the design and manufacturing time of polymer patterns through the use of 3D printing contributes to the adaptability of enterprises to market changes, the implementation of the "on-demand" production model and the digitalization of the casting process with the minimization of time and resource costs.

Selection and justification of protective coating systems for the protection of carbon steel pipe markings

2025-11-12T05:14:21+02:00

Objective. This study investigates the corrosion resistance of a complex paint-and-varnish coating applied to protect markings on pre-painted pipes. The aim is to select the optimal coating material for the corrosion protection of pre-painted and pre-marked pipes. Methods. The subject of the study is a set of paint-and-varnish materials applied to carbon steel pipes to protect their markings. Standard methods were used to assess the coatings’ corrosion resistance, adhesion to the pipe surface, and abrasion resistance. Results. It was found that F410SP, SIGMAFAST 40, Alpina Yachtlack, Helios MIKS, and SK-1 possess the required corrosion resistance and adhesive strength for use as protective coatings for carbon pipe markings. Considering material consumption and drying time, Helios MIKS and SK-1 are recommended for industrial application. Scientific novelty. This study is the first to examine the effectiveness of transparent paint-and-varnish coatings for the anti-corrosion and mechanical protection of carbon pipe markings. These coatings provide long-term durability, legibility, and preservation of the markings during transportation, storage, and operation under harsh conditions, while also withstanding high temperatures, humidity, and UV exposure. When other marking methods are not feasible, the optimal selection of protective coating properties is essential to ensure the integrity of the surface layer without creating stress concentration zones or corrosion-prone areas. Practical significance. The study provides objective data on the potential for industrial use of paint-and-varnish materials available on the Ukrainian market to protect markings on carbon pipes.

Analysis of regulatory support for accreditation procedures in steel shot production

2025-11-12T05:22:50+02:00

Purpose. Analysis of DSTU 3184 requirements for spherical steel shot and heat-treated spherical steel shot in the context of ensuring production accreditation procedures. Methodology. The research material was manufactured by SE “STALZAVOD TAS” using the method of steel melting and pouring into rotary nozzles with subsequent atomization of the melt on a water curtain to form shot particles. Metallographic analysis was performed using a NEOPHOT-32 optical microscope. Findings. The analysis of DSTU 3184-95 requirements for spherical steel shot type was carried out with regard to its size distribution, microstructure, unacceptable defects, heat treatment, and chemical composition. It was established that the distribution of steel and cast-iron spherical shot into 10 nominal sizes specified by DSTU 3184 does not correspond to international standards for this type of product. According to DSTU 3184, the chemical composition of the shot is determined by the manufacturer, which decreases the level of regulatory control. The necessity of aligning the regulated microstructure of heat-treated steel shot with its chemical composition was identified. Requirements for unacceptable defects under DSTU 3184 include the ratio of maximum to minimum particle diameter, the area of shrinkage porosity, the length of the largest crack, and the area of the largest cavity; however, they do not take into account such typical defects for this product as gas pores and non-metallic inclusions. Originality. A comparative analysis of the requirements of national and international regulatory documents and technical specifications regarding permissible defect levels in steel shot was performed. The study revealed that DSTU 3184 provisions are inconsistent with modern requirements concerning the regulation of chemical composition and its compliance with the declared microstructure. Practical value. The revision and adaptation of DSTU 3184 regulatory requirements to current technical realities and international standards are substantiated as critical factors for maintaining the competitiveness of domestic products in both national and international markets.

The potential of implementing AI-driven quality control in Ukrainian investment casting facilities

2025-11-12T05:32:07+02:00

The purpose of this study is to assess how AI can reduce energy consumption, labor intensity, and scrap rates, thereby improving yield and long-term operational efficiency of investment casting foundries. The methodology includes a literature review and feasibility analysis conducted using recent academic studies and industry case reports from 2013 to 2024. Additionally, the study conducted a basic cost-benefit analysis comparing implementation expenses with potential annual savings in scrap reduction, labor optimization, and material efficiency. Findings indicate that key AI applications include process-parameter modeling and machine learning prediction, and automated defect detection through deep learning-based visual and radiographic inspection. Research shows that AI systems can reduce casting defects by 30–50%, with substantial savings in labor and material costs. The study highlights low-cost and open-source options for AI deployment, increasing accessibility for resource-constrained facilities. The originality of the paper is its emphasis on the practical implementation of AI-driven quality control solutions for Ukrainian foundries, investment casting facilities in particular. The practical value of the study lies in a structured, actionable roadmap, including software and hardware requirements, and cost and ROI estimates, that can assist local foundries in beginning their Industry 4.0 transition with a focus on quality optimization.

Study of the effect of gaseous elements on metal macrostructure during cooling

2025-11-12T05:40:38+02:00

The article presents a study of the influence of gas elements (oxygen, hydrogen and nitrogen) during metal processing with a mixture of gases (argon, nitrogen) on the macrostructure of the metal after cooling. One of the most common methods of ladle processing of steel is the process of blowing metal with inert gases and its vacuuming. A mathematical model has been developed that allows us to consider the process of gas removal and calculate the quantitative indicators of the removal of dissolved gases from the metal during its processing. Taking into account the thermodynamic and kinetic features of the dissolution of gases in the metal during blowing metal in the ladle with inert gases and during vacuuming allowed us to clarify the physicochemical processes of gas behavior in the metal, which will lead to the possibility of developing a new technology of ladle processing of metal using mixtures of inert gases.

Simulation of roll forming for U-shaped bent profiles

2025-11-12T05:44:58+02:00

Purpose. To develop an approach for simulating the roll forming process of U-shaped bent profiles using the QForm software package. Methodology. The study is based on the finite element method implemented in QForm. The process was simulated in a 3D environment, accounting for elastic–plastic deformation, using a single operation of the «Sheet Bulk Forming» type. A sequential forming scheme was implemented using 12 roll stands, which incorporated the elastic–plastic properties of the material. Appropriate boundary conditions were defined to replicate real technological parameters of the roll forming process. Results. The simulation yielded stress and strain distributions in the blank at various stages of its passage through the roll stands. It was found that maximum plastic strains occur in the bending zones, while the edge regions are predominantly subjected to tensile stresses. The simulation results are consistent with the physical nature of the bending process and confirm the validity of the proposed approach. Scientific Novelty. An adaptation of the QForm software package is proposed for simulating the roll forming of bent profiles, which is not covered by its standard modules. Simulation algorithm and boundary condition setup were developed, enabling the analysis of the stress–strain state of the blank during profile formation. Practical Significance. The results of the study can be used to optimize technological parameters of the roll forming process, reduce the likelihood of defect formation, and expand the functional capabilities of QForm in the field of sheet metal forming simulation. The proposed approach is valuable for technologists, engineers, designers, and researchers working in the field of metal forming.

Ways to improve technology and equipment for sinter production

2025-11-12T05:51:40+02:00

The article is devoted to a comprehensive analysis of key areas for improving technologies and equipment in sinter production, which is critically important for optimizing metallurgical processes and minimizing economic costs. Based on the results of a semantic analysis of information flows that determine interest in research in metallurgy, four key components have been identified: “technology,” “raw materials,” “equipment,” and “ecology.” The authors emphasize the need for a systematic approach to the modernization of sintering production in order to create new technologies, improve raw material preparation, develop new-generation equipment, and reduce the negative impact on the environment. The article examines in detail eight target functions for optimizing the sintering process, including the specific productivity of the sintering machine, the stability of the chemical composition of the sinter (iron content and basicity), the proportion of fine fractions, the range of fractional composition, impact and abrasion resistance, and recoverability. A comparison of current sinter indicators with blast furnace smelting requirements is carried out, revealing significant discrepancies. Structured measures aimed at achieving optimal values for each of the target functions are presented, taking into account that these factors and functions are not additive. It is emphasized that economizing on sinter production does not always coincide with economizing on its use in blast furnace smelting; in particular, increasing the strength of sinter can negatively affect its recoverability and economic performance. Particular attention is paid to the issue of increasing the recoverability of sinter, which is key to reducing coke consumption in blast furnace production. Technological solutions are considered to increase the productivity of sintering machines, stabilize the chemical composition of sinter (through effective averaging of charge materials and accurate dosing), increase the iron content (using high-quality ore, concentrates, hybrid materials), and optimize basicity. The importance of a narrow fraction composition of sinter for ensuring a stable gas-dynamic regime of blast furnace smelting is highlighted separately. Based on the analysis of the presented data and world experience (Japan, Belgium), it is concluded that investments in improving the quality of sinter and coke at the initial stages of production pay off due to a significant reduction in coke consumption and an increase in the productivity of blast furnaces. The article contains specific recommendations for the reconstruction and development of new equipment to implement the proposed improvements.

Mathematical modeling of the pipe pressing process using the QForm package

2025-11-12T06:04:13+02:00

Purpose of the work. Creation of a mathematical model of the process of hot pressing of pipes, development and improvement of the technology and design of the technological tool by determining the dependencies between the temperature-deformation and plastic characteristics of the metal under conditions of intensive plastic deformation. Research methodology. The mathematical model is based on a system of equations, which includes the equilibrium equation, the equation of connection between the velocity field of material points and deformation rates, the equation of connection between the stressed and deformed state, the incompressibility condition, the plasticity criterion, the energy equation. The resistance to deformation of the workpiece material is considered to depend on the accumulated deformation, the current deformation rate and temperature. Results. The modeling of the pipe pressing process was carried out for steels of austenitic class 12X18N10T and ferritic class 12x13 for pipes with dimensions of 45x4.0-5.0 mm, 88.9x6.45 mm, 114x6.88 mm and 219x 7.0-8. This model used the friction law of Levanov A.N., according to which the coefficient of friction on the metal-tool surface is within 0.015-0.02. The adequacy of the model was checked using the geometric parameters of the pressed products (pipes 45x4.5 mm and pressing forces for pipes with dimensions 45x4.0-5.0 mm, 114x6.88 mm and 219x 7.0-8.0 mm. Analysis of the results of the process modeling, completion speed, normal and tangential stresses. Scientific novelty. For the first time, data on the distribution of temperature, degree and rate of deformation, normal and tangential stresses in the deformation center during pipe pressing were obtained using the finite element method, which is distinguished by taking into account experimentally determined rheological properties of steels and comprehensive accounting of the regularities and features of elastic-plastic, thermal and kinematics. Practical significance. The use of the obtained data allows us to determine rational temperature-deformation and speed parameters for pressing pipes, which ensure the minimization of the probability of defects on the surface of the products.

Improvement of methods for calculating the distribution of charge components in the volume of a blast furnace

2025-11-12T06:12:09+02:00

The analysis of known calculation methods and mathematical models of the distribution of charge materials on the top of a blast furnace, used in technological and research practice, was performed. It was noted that mathematical modeling, including those based on the discrete element method (DEM), and experimental studies (both in industrial conditions and using physical models) are used to determine the distribution of charge in a blast furnace. At present, there are no instrumental means of controlling the distribution of charge components. It is shown that the distribution of components on the surface of the backfill is the result of the interaction of a number of processes occurring at all stages of the formation of portions of charge materials, their delivery to the top and unloading into the furnace. There are three approaches to describe the process of the movement of charge materials in hoppers, on the basis of which mathematical models have been created for specific objects at the present time and results acceptable for practical use have been obtained. The first one - in the form of geometric dependencies determines the volume of the zone of active material movement, the shape of which is determined experimentally, and the volumes of bulk material arrays, which in a given sequence enter further into the zone of active material movement, and then move vertically to the outlet of the hopper. The second approach is an attempt to take into account the kinematic patterns of bulk material movement in the zone of active movement in combination with the provisions of the first approach to describe the behavior of bulk outside the active zone. The third approach is based on DEM, mathematical models based on which require input data, the receipt of which causes difficulties in determining, or data, the reliability of which does not have sufficient confirmation. A developed complex mathematical model of the formation of multicomponent portions of charge materials, their loading into the hopper of a cone-free loading device (CFLD), unloading from the hopper and distribution on the surface of the backfill is presented, which was created on the basis of the synthesis of a number of models developed and improved by the Institute of Ferrous Metallurgy Z.I. Nekrasov of the National Academy of Sciences of Ukraine of mathematical models that most fully describe the entire complex of processes of loading a multicomponent charge into a blast furnace. The model provides determination of the current component composition of the flow formed during unloading of multicomponent portions from the BLT hopper, and the full composition of mixtures of charge components in various annular zones of the top. The developed complex model is successfully used by the Institute of Ferrous Metallurgy Z.I. Nekrasov to solve a number of technological problems regarding the selection of rational loading modes of operating blast furnaces operating on a multicomponent charge, including the selection of parameters of special loading modes that ensure the creation of the necessary conditions for lining or washing depending on the current requirements of the smelting process. Information on the distribution of charge components across the furnace cross-section, which can be obtained using the developed complex model, is also necessary for conducting analytical studies of physical - mechanical and physical - chemical processes in a blast furnace, in particular, the conditions of slag formation and the distribution of melt properties in the volume of the blast furnace.

Complex solid-phase reduction in a blast furnace of self-healing pellets of cold agglomeration containing by-product carbon materials of metallurgical production

2025-11-12T06:22:25+02:00

The reactions of direct and indirect reduction occurring during the heat treatment of self reducing pellets (SRP) have been studied. In this investigation Blast furnace (BF) sludge which contains particles of coke, has been included in the SRP blend as a source of solid reductant. In the SRP as a part ot the blast furnace burden occur the reactions simultaneously: inside of SRP-direct reduction by C_solid; gasification of carbon and indirect reduction by CO; and outside of SRP-indirect reduction of iron bearing oxides by reducing gas coming from the hearth of blast furnace through the column of charged materials. The experiments was performed continuously from the start temperature (~200 ˚C) to the experimental temperature (500 ˚C; 700 ˚C; 900 ˚C; 1100 ˚C) in argon free environment. Upon reaching the desired temperature argon was replaced by hydrogen during 30 minutes. After that the reduced probe of SRP was cooled in argon. The objective of the present work is to research a quantitate ratio of degree direct reduction inside of SRP and degree of indirect reduction outside of SRP on the top of the blast furnace.