Search

The paper presents a brief analytical review of the current state of research in the field of recovery and its modeling in order to predict the structure and properties, as well as a review of experimental research methods and mathematical models of the processes of structure formation during annealing of cold-rolled steels. The paper also presents the results of an experimental study of the recovery process in cold-rolled automotive steels using various techniques and describes a mathematical model for calculating the kinetics of this process depending on the temperature and chemical composition of steels. [ABSTRACT FROM AUTHOR]

This paper presents a variant of compensation for the occurrence of an impact load during the operation of a rolling mill using a regulatory method based on the integration of a neural network into a control device. The neural network can effectively select the speed and preacceleration time for the main drive of the rolling stand. Due to the neural network adaptation, the system receives information updates during the process of work, predicting changes in the technological process. A block diagram of a neural network is developed. This work describes the developed block diagram of the main electric drive of the rolling mill, which includes an additional speed sensor based on an automatic adjustment system with a neural network, which is employed to improve the quality indicators of the engine preacceleration control. Experiments on the developed system showed that when using a neural network, the maximum value of the resulting torque decreased by 9.8% with decreasing speed overshoot by 14.3%. Using an automatic control system based on prediction with the use of neural networks, it was possible to decrease the kinetic moment occurring during the metal rolling process. [ABSTRACT FROM AUTHOR]

Reducing the volume of manual work improves the processing speed of blanks, along with reducing the number of rejected products and overall production costs in large batches, while increasing repeatability. The concept of lean manufacturing is gaining popularity among manufacturers, with one of its main goals being the continuous elimination of waste. The paper presents a method for enhancing the production technology of cast blanks for gas turbine engine blades. Device designs were developed to minimize losses during the production of castings. [ABSTRACT FROM AUTHOR]

The paper analyzes the possibility of creating a titanium porous fiber material for implants, which is made of fibers of various transverse sizes and has gradient pore architecture. The architecture of the porous space, structure, and mechanical characteristics of such material have been studied. It is shown that the strength of the porous fiber material can be improved by increasing the temperature of diffusion bonding and by performing hydrogen heat treatment. The specifics of the mechanical behavior and fracture of the material samples were studied by performing a fixed-end bending test. [ABSTRACT FROM AUTHOR]

In this paper the influence introducing various plasticizers into an initial charge on the structure and properties of iron-based powder materials alloyed with copper is considered. It is shown that introduction of copper stearate into an initial powder mixture and warm mixing, pressing and subsequent sintering makes it possible to obtain low-porosity workpieces with relative porosity of 95%. Pores within the workpieces obtained have a small size of 10–15 microns and a rounded shape. Also, bending strength is determined for sintered samples of all the compositions of powder mixtures studied and the Rockwell hardness is determined on the C scale. Powder steels based upon mixtures have the best set of mechanical properties PZhRV 2.200.28 + 0.7 wt.% Br + 0.7 wt.% Cu + 1 wt. % StCu + warm mixing—hardness HRC 58. flexural strength 600 MPa PZhRV 2.200.28 + 1.4 wt.% Br + 1.4 wt.% Cu + 1.4 wt.% C + 1.0 wt.% StFe + warm mixing—hardness HRC 100, flexural strength 530 MPa [ABSTRACT FROM AUTHOR]

The paper discusses specifics of the process of carbothermic reduction of metallurgical silicon in ore-smelting furnaces. The reaction zone represents a heating area for the charge materials, formed around the electrodes in all electric furnaces, and facilitates the release of thermal energy by passing electric current through a resistance and/or by creating an electric arc, change in the aggregate state of the loaded materials (e.g., quartzite, bituminous coal, needle coke), and a complex of chemical reactions that occur within such materials. When properly controlled, the operating conditions of the ore-smelting furnace provide optimal specific performance relative to specific power consumption. However, in case of deviations, such as high or low placement of the electrodes, excess or lack of reducing agent in the charge material, furnace throat level being too high or too low relative to technical guidelines, electrode voltage imbalance, etc., the furnace performance can be significantly reduced due to a non-conformant granulometric composition. If the furnace is operated with such deviations for extended periods of time, an emergency shutdown may occur. If the power generated at the electrode is insufficient, the reaction zone becomes significantly narrower, this leads to a change in the rate of chemical reactions. The excessive power levels, on the other hand, may cause intensive entrainment of microsilica along with the formation of blowholes capable of disabling water-cooled panels or shutting down the furnace transformer due to an overload. The location of the reaction zone in the furnace space plays a key role in ensuring effective operation of the ore-smelting furnace. Shifting of the reaction zone upward or downward may result in the grade drop of metallurgical silicon and reduced performance of the furnace, which will subsequently increase the product cost. [ABSTRACT FROM AUTHOR]

In this paper, the results of the study on the deformation effect by the screw piercing method on the mechanical properties and macrostructure of a continuously cast blank made of wheel steel are presented. It is revealed that when piercing in a screw rolling mill with small extraction coefficients of the billet (feed angle β = 14°, extraction coefficient μ ~ 1.36), the quality of the macrostructure improves, the strength properties (σv, σ0.2) increase by 1.1–1.6 times, the plastic properties (δ, ψ) improve by 1.4–5.4 times, and the impact strength of the wheel steel increases. [ABSTRACT FROM AUTHOR]

This paper presents examples from the practice of operating arc steel-smelting furnaces (EAFs), verifying the hypothesis on the complex heat exchange of arcs in spherical segments in the bath. The thermal radiation of arcs in spherical segments is converted into convective and thermal conduction flows, heating the entire volume of metal and slag. No more than 3%–4% of the arc power is spent on evaporation of the metal under the arcs, while 76–78% of the arc power is converted into convective and thermal conduction flows that heat the bath. The metal waste under the arcs is 8–9%, in which 91–92% of the metal waste is accounted for in the zones of exposure to the bath with oxygen. With an oxygen consumption of 10–15 m3/t in the EAF, metal waste is 3%; with an increase in oxygen consumption to 50 m3/t, metal waste increases by 2.5–4 times to 7.5–12%. With an increase in the absorption coefficient of the gaseous atmosphere of the DSP-100 furnace, the maximum density of thermal radiation fluxes from the arcs to the walls decreases proportionally. With an increase in the height of the slag layer by 3.7 times, the maximum density of thermal radiation fluxes of the arcs on the water-cooled wall panels decreases by 2.6 times. [ABSTRACT FROM AUTHOR]

The article presents the results of computer simulation and experimental rolling of 0.55 mm thick, 100 mm wide tapes made of AD33 aluminium alloy on an industrial 175 × 300 double-roll mill under different contact friction conditions. The study quantifies the impact of technological lubricants on the distribution of rolling forces, moments, and powers along the tape length. It has been shown that the use of technological lubricants reduces the force and power parameters compared to dry rolling. When simulating the rolling process of tapes made of AD33 alloy with I40 technological lubricant (5%), the rolling force decreases by 6.72 kN (7.9%), the rolling moment—by 0.026 kNm (12.6%) and the rolling power—by 0.098 kW (12.8%) compared to dry rolling. When the rolls are lubricated with kerosene, the rolling force decreases by 8.8%, the rolling moment—by 18.8%, and the rolling power—by 18.6%. The results of computer simulation of rolling with various technological lubricants have led to the development and implementation of a new rolling mode on a 175 × 300 double-roll mill using I40 industrial oil as the technological lubricant. The new mode ensures the specified thickness accuracy of 0.55 ± 0.01 mm along the length of AD33 alloy tapes, significantly reduces the deformation time, and decreases the loads on equipment (by 5–8%) at the machine-building plant in Dong Nai city. [ABSTRACT FROM AUTHOR]

Piercing represents one of the key processes in the production of hot-rolled pipes on screw rolling mills due to its determinative effect on the quality of the resulting bloom. The main factor affecting the quality of hot-rolled pipes is the wear resistance of the working tool. The work equipment frequently fails due to high wear of the surface. It is known that the mandrel affects the quality of the inner surface of the resulting pipes and the accuracy of geometric dimensions. In addition, increased wear of piercing mandrels leads to a decrease in the productivity of industrial units. In this paper, the mandrel wear was studied during the piercing of billets, made of 12Kh18N10T corrosion-resistant steel, into pipes on a MISiS-130D pilot-industrial screw rolling mill. Using the SolidWorks software package, the process of piercing blanks with a diameter of 60 mm and a length of 400 mm was simulated in order to assess the wear of mandrels using the QForm software package. The modeling of piercing processes was carried out by varying the rolling conditions: rolling speed, feed angle, and ovalization factor of the deformation zone. It is concluded that the distribution of the wear value along the length of the mandrel is uneven; the dependence of the mandrel wear value on the variable technological factors of the piercing process is revealed. The dependence of the wear depth of piercing mandrels on the temperature of their working surface and the duration of rolling was studied. Methods for increasing the wear resistance of piercing mandrels based on the selection of rational rolling modes are proposed. [ABSTRACT FROM AUTHOR]

Tajikistan possesses large reserves of dump tailings characterized by a high gold content. The formation of these dump tailings is associated with the low cost of gold in the past, since rich ores with a gold content above 6–8 g/t were more often involved in processing. At recovery of ≈ 70–75%, tailings with a gold content below 1.8 g/t were disposed of. The paper studies the material composition and carries out an assessment of the degree of refractoriness of the studied dump tailings to leaching. It was established that the main components of tailings are SiO2 and Al2O3. The dump tailings contain 2.4 g/t of gold and 7 g/t of silver. In terms of material composition, the sample of the dump tailings belongs to a readily cyanidable type. Gold finely disseminated in acid-soluble minerals represents 6–6.5%, while minerals insoluble in acids and quartz contain 15% of gold. In addition, the tailing sample contains gold encapsulated in minerals soluble in sulfuric acid. In terms of gold form, the dump tailings are classified as medium refractory to leaching processes. The diagnostic leaching test results for gold showed that the use of thiourea as a lixivant in the further development of the leaching process is promising. Gold recovery by thiourea leaching was 78%. [ABSTRACT FROM AUTHOR]

This paper is dedicated to studying the effect of replacing molybdenum with vanadium on the tendency to amorphisation, structure, and thermal properties of high-entropy alloys of the (Fe0.25Ni0.25Co0.25Cr0.125Mo0.125‑xVx)100‑yBy system, where x = 0; 0.0625; 0.125 and y = 17–25. The alloy structure was analyzed using X‑ray diffraction, scanning and transmission electron microscopy methods. Thermal properties were determined by differential scanning calorimetry. It was found that the replacement of molybdenum with vanadium leads to the formation of crystalline particles of complex nitrides (V, Cr, Mo)(N, B) in the ribbon structure. The dependences of the characteristic alloy temperatures have been established. Molybdenum replacement with vanadium was shown to stabilize the supercooled liquid in alloys with completely amorphous structure. [ABSTRACT FROM AUTHOR]

In order to achieve enhanced dimensional and geometric accuracy in castings from a broad range of alloys, special processes are typically used, whose improvement, in some cases, aims to eliminate the need for machining operations on the blanks. One such process is experimental investment casting using consumable porous patterns obtained by pressing wax-like powders of model compositions. When forming the surface of such porous patterns, the geometric parameters of the mold cavity of the press die, whose design ensures the directed transfer of load from the pressing elements to the entire volume of the compacted material, are of paramount importance. During the development of the method for obtaining experimental patterns, it was possible to eliminate defects arising due to thermophysical phenomena in materials (mainly due to their internal porosity): shrinkage of the pattern material, formation of cracks within the ceramic mold, and its failure. The observed phenomena that lead to defects occur at various stages of the technological process, including the production of investment patterns and ceramic shell molds, the melting of ceramic model materials, and the casting of the melt into the molds. In addition to the definite advantages of this approach to forming compact structures, a disadvantage should be mentioned: the variation of their geometry due to the elastic return of the compacted material resulting from overconsolidation or uneven loading of compact sections of varying thicknesses. It is possible to achieve controlled loading of a powder body by compacting it under centrifugal forces to obtain compacts of complex configurations, including bodies of revolution. This paper examines the influence of various process parameters, which accompany the action of the centrifugal field, on the characteristics of compacted powder bodies made from wax-like materials used to create pressed investment patterns with improved dimensional and geometric accuracy. The study compares the calculated rotation speed of the press dies, ensuring the compaction of the powder body to a technologically acceptable density while considering its desired geometry, with the experimental results. The paper also identifies scenarios to enhance the energy efficiency of powder body compaction from wax-like composite materials under centrifugal forces. [ABSTRACT FROM AUTHOR]

The paper offers a detailed description of the application and significance of machine learning methods during various processing stages of modern metallurgy. The relevance of this topic is based on the significant positive technical and economic effects from the use of machine learning noted by both Russian and world-leading manufacturers in the field of metallurgy. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental studies of heat transfer in electric arc furnaces, which showed that heat fluxes incident from arcs on a heating surface comprise 85%–95% of thermal radiation fluxes. The thermal radiation laws of ionized and nonionized gas volumes are stated, according to which the heat transfer in electric arc furnaces is calculated. The experimental and calculated data on the heat fluxes of arc radiation on a heating surface differ by no more than 5%–8%, indicating that the thermal radiation laws of gas volumes correspond to real heat transfer processes in electric arc furnaces. The heat exchange of arcs in an electric arc furnace bath was calculated. When the arcs are completely buried in the recesses of the bath, their slag and heat radiation fluxes are converted in the recesses into convective heat fluxes and heat conduction flows, heating the entire volume of the metal bath and slag. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of NaCl on the secondary oxidation rate of hot-briquetted iron (HBI) during its transportation to consumers in Russia, former Soviet republics, and other foreign countries by both rail and water transport. This results in distinct atmospheric conditions surrounding the briquettes, leading to varied oxidation processes. This study is significant as the oxidation rate directly affects the metallurgical properties of the briquettes. The article presents experimental investigations on the impact of different NaCl concentrations (0–4%) in water, which evaporates into the atmosphere surrounding HBI, on its reactivity. The findings reveal that the reactivity of briquettes increases with up to 4% NaCl content in the water surrounding the HBI. Consequently, the iron oxidation rate in the briquettes also rises, with reactivity increasing from 0.234 to 0.412 nm3/(ton·day) and the rate from 0.0833 to 0.1459 kg/day. These results suggest that seawater, particularly with NaCl content up to 4%, significantly impacts the iron oxidation rate in HBI. Therefore, when transporting by sea, it is essential to consider this influence and implement measures to mitigate this type of oxidation. [ABSTRACT FROM AUTHOR]

The paper examines the technological properties of diverse vanadium-containing raw materials, including titanium-magnetite concentrate, converter slag, dump sludge, neutralization sludge, slag from ferrovanadium smelting, fuel oil ash and slag, black shale, and spent catalysts. The existing chains of their formation and processing are described, considering the volume of raw materials underutilized for vanadium extraction, such as blast furnace slag, tailings, ilmenite concentrate, red mud, vanadium slag, and titanomagnetite concentrates. Most of these materials prove suitable for vanadium extraction. According to our estimates, annually produced industrial raw materials involve approximately 53.6 thousand tons of vanadium relative to V2O5. This includes 4.4 thousand tons of V2O5 suitable for extraction and 12.0 thousand tons of V2O5 potentially suitable for extraction. Additionally, about 28.5 thousand tons of vanadium relative to V2O5, found in titanium magnetite concentrates and converter slag, could be further engaged in processing. Consequently, the reserve of raw materials unused for vanadium extraction amounts to 45 thousand tons relative to V2O5. Processing these raw materials holds the potential to manufacture vanadium-containing products of a deeper degree of processing, including purified vanadium pentoxide V2O5, vanadium trioxide V2O3, and vanadium alloys, thereby reducing dependence on imported equivalents. [ABSTRACT FROM AUTHOR]

The paper introduces a mathematical model based on the discrete element method, presenting the results of its application to simulate the movement of briquetted mass within the working chamber of the extruder. This model accounts for the adhesive interaction among particles within the mixture. The simulation results provide a qualitative and quantitative description of the displacement and compaction of the briquetted mass. They allow the flow structure to be visualized and the distribution of velocities and the moment on the screw axis during the extrusion process to be determined. Furthermore, a digital twin of the pug sealer–extruder unit was created through finite element modeling. The results obtained from this digital twin can be used to optimize the operational parameters of extrusion briquette equipment. In addition, by using the developed model, the process of mixing binder materials with a briquetted mixture at various volumes of the added binder was studied. [ABSTRACT FROM AUTHOR]

Electromagnetic stirring (EMS) of the liquid phase of billets is one of the most technologically advanced methods to enhance the macrostructure quality of continuously cast slabs produced on high-performance continuous casting machines (CCMs). Under the influence of EMS, a forced movement of the melt is created relative to the crystallization front. The temperature gradient across the cross-section of the slab and the chemical composition of the steel are stabilized via heat and mass transfers. A project was implemented at Novolipetsk Iron and Steel Works to equip a slab CCM with an EMS system in the secondary cooling zone of a continuously cast ingot (CCI). This paper presents the industrial development results of the teeming electrotechnical steel technology using the EMS system. Furthermore, the key aspects of stirring and technological parameters of teeming electrotechnical steel are presented. The effect of EMS on the quality of a CCI is confirmed in terms of crystallization structure variations with an increase in the zone of equiaxed crystals by more than twice in comparison with the typical teeming practice. Furthermore, it has been established that using EMS can effectively influence liquid steel and considerably enhance the quality of the CCI macrostructure and the uniformity in the properties of finished rolled products. [ABSTRACT FROM AUTHOR]

The global warming and climate change caused by the continuing rise in carbon dioxide (CO2) emissions have attracted the attention of the public, scientists, and governments in recent years. An effective approach to limit the impact of such emissions is the implementation of advanced carbon capture and storage systems. This paper provides an overview of technologies and recent advances in carbon capture and utilization. The main methods include postcombustion, precombustion, and oxyfuel-combustion, adsorption, and membrane capture. In addition, various problems associated with the storage, transportation, and utilization of CO2 are discussed. [ABSTRACT FROM AUTHOR]

Searching for alternatives to diversification of production facilities that do not require significant material and energy costs is relevant in the face of pressing external factors. One of the promising technological fields of alloy production in metallurgy is the application of aluminothermic processes of remelting of thermite charge consisting of secondary materials (scale, chips of ferrous and nonferrous metals), used to produce a wide range of metal products without significant costs associated with the reequipment of production units. The possibility of controlling the parameters of alloys and properties of the final metal product formed by aluminothermic processes is implemented primarily by reducing the temperature of the metal phase of the melt by introducing inert fillers into the composition of mixtures, as well as holding the melt in the crucible before casting. The chemical composition, structure, and physical and mechanical properties of iron-carbon alloys are significant in forming several operational characteristics. The paper presents experiments aimed at studying the effect of the initial components of thermite charge materials used to produce iron-carbon alloys in aluminothermic processes, as well as the melt holding time in a crucible before casting on the chemical composition, microstructure, hardness, strength indicators, and the fracture characteristics. The focus of experimental investigations is on industrial applications in the metallurgical and machine-building sectors. [ABSTRACT FROM AUTHOR]

The paper presents a research study into the effect of temperature on the properties of a mandrel and a punch during hot screw rolling and subsequent forging of 1000 medium-carbon structural steel vessels at the rolling and pressing line of the BF JSC NPO Pribor machine-building enterprise. According to the performed study, the main cause of downtimes in the technological production cycle and decreased geometric quality indicators of rolled products is related to deteriorated mechanical properties of the deforming tool. Significant temperature variations (more than 250°C) along the length of the piercing and pressing tool, made of 4Kh5MFS steel, during the hot pressure treatment were revealed. The main reasons leading to deterioration of the tool quality were established, including the loss of its strength and hardness, as well as an increase in the ductility of a piercing mandrel and a punch of up to 30 and 19%, respectively. The study identified rational ways to extend the service life of the most loaded processing tools and decrease the cost of vessels at the exit of the rolling and pressing line by 3–5%. [ABSTRACT FROM AUTHOR]

Al–3Ti–1B and Al–5Ti–1B master alloys represent the most popular modifiers for the majority of aluminum alloy groups. To date, several methods, requiring various conditions and resource costs, have been applied for producing these master alloys. The paper presents the results of a comparative analysis of methods for producing Al–3Ti–1B master alloy using both a Ti sponge and salts (K2TiF6 and KBF4) as the starting components. The degree of Ti and B recovery for three methods of the master alloy production was experimentally established. The phase and element compositions of slags were studied; the amount of fluorine gas, emitted during the master alloy production, was calculated. A method, using a titanium sponge and molten KBF4 + KCl mixture, was identified to ensure a recovery of Ti and B equal to 88.10 and 72.20%, respectively. The modifying ability of the produced master alloys was studied both according to the TP-1 method and using the laboratory and industrial unit of semi-continuous casting. [ABSTRACT FROM AUTHOR]

The paper considers stresses emerging in the skin of a continuously cast steel billet, as well as their values under the influence of temperature expansions in a novel patented design of a nickel mold with a two-circuit cooling system. According to the known values of heat flux densities at various distances from the top of the mold, the temperature of the slag-forming mixture and the average temperature of the steel billet skin are determined. Based on the established thickness of the billet skin, the temperature gradient therein is determined. At a steel casting speed of 4 m/min, the values of temperature stresses in the billet skin at various distances from the top of the mold were established not to exceed the values of the metal flow stresses at corresponding temperatures. [ABSTRACT FROM AUTHOR]

The paper presents the results of structural studies and assessment of the level of bending strength of an alloy based on nickel aluminide (VKNA-1V) obtained by spark plasma sintering of mechanically activated powders of the initial components at different sintering conditions. Sintering temperature was the main variable parameter (range: 1,100 to 1,250°C). It has been established that when the sintering temperature exceeds 1,200°C, the formation of a liquid phase occurs. X-ray diffraction analysis of the studied materials revealed Ni3Al as the main phase. The recommended sintering conditions required to obtain a dense, low-defect billet made of VKNA-1V alloy include sintering at 1,150°C for 5 min under a pressure of 40 MPa. This type of material has an increased level of bending strength at room temperature (σbend = 1,640 MPa) and a microhardness equal to 650 HV. [ABSTRACT FROM AUTHOR]

The paper presents a description of the information modeling system for the distribution of hot blast and natural gas through the tuyeres of a blast furnace. The developed system is distinguished by considering the main physical and chemical laws and ongoing processes in the control object. The system is based on the method of determining the blast flow through the air tuyeres using the thermal power of the flow passing through the tuyere and the value of the heat removal taken from this tuyere. Based on the calculation results, the system determines the main parameters of the blast mode of the blast furnace and the parameters of individual tuyere hearths, including the theoretical combustion temperature, the blast velocity from the tuyere, the kinetic energy of the blast, the length of the oxygen and carbon dioxide combustion zones of the tuyere hearth, and others. The required natural gas consumption through the blast furnace tuyeres is calculated, which ensures the maintenance of the theoretical combustion temperature in the blast furnace tuyeres at a given level in the design mode. The architecture of the software is described, the characteristics of the modules are presented, and its operation is illustrated. The developed software can be used by the technological personnel of the blast-furnace process to improve the efficiency of blast-furnace smelting. [ABSTRACT FROM AUTHOR]

The pores that occur during the casting process adversely affect the fatigue characteristics of the Al–Si alloys (silumins). The effect of casting pores under fatigue is associated with a number of factors, such as pore size, morphology, and position inside the cast part. Metallography can be used for the statistical characterization of pores. However, random two-dimensional sections through the pores fail to provide a reliable estimation of defect size without additional data analysis. This paper presents two experimental methods, namely X-ray computed tomography and metallography, which are used to characterize the size and morphology of the pores in the AlSi7Mg alloy casting. Three-dimensional data obtained by X-ray computed tomography were used to evaluate the criteria for determining the pore size based on metallographic measurements. The stress concentration resulting from the actual 3D morphology of pores was further investigated by the finite element method and compared with simplified 2D models of pores. [ABSTRACT FROM AUTHOR]

Increased industrial production stimulates the development of procurement industries. Technological processes for the production and processing of materials and products are being improved to reduce the material consumption for production, increase economic efficiency, reduce the environmental burden, and increase reliability and durability of machines. The tasks in modern mechanical engineering determine the material and component requirements of machines and mechanisms. New methods for processing known available materials to improve the complex of their properties to use them in new areas, including under conditions of complex loading and undesirable external influence. Our paper discusses a new method for the intensive plastic deformation of metal billets in the form of a hemispherical layer made of high-purity aluminum. Hardening of materials by severe plastic deformation is a widely used method for improving the mechanical characteristics of materials and products, including those not hardened by thermal processing. However, the possibility of this improvement method is limited by the strength of the materials processed. This article presents the results of experimental and theoretical studies on the hardening process of hemispherical billets, including a mathematical model of the process based on the deformation theory of plasticity. [ABSTRACT FROM AUTHOR]

The paper considers principles of combining technology for preparing new powder materials from solid alloy waste by electroerosive dispersion of T5K10 alloy waste in a liquid working medium (water) and compaction technology by spark plasma sintering. It is established by experiment that hard alloys made of electroerosion dispersed T5K10 alloy particles prepared by spark plasma sintering under rapid heating conditions and a short working cycle duration have better physical and mechanical properties compared with industrial hard alloys from which the initial powder particles were obtained due to suppression of grain growth and obtaining an equilibrium state within a submicron grain size. [ABSTRACT FROM AUTHOR]

This paper presents the results of testing under production conditions of the technology of rolling transformer steel strips with edge-drop compensation using a hot-rolling mill (model 2000). The obtained results show the fundamental possibility of edge-drop compensating of hot-rolled strips of transformer steel to reduce the side scrap of the finished strips. [ABSTRACT FROM AUTHOR]

The paper discusses the development of a technological scheme for the comprehensive processing of copper cable conductors with a contact surface coating containing lead. A hydrometallurgical method for removing (leaching) lead from the surface of copper conductors of the cable scrap by using solutions consisting of a mixture of acetic acid and hydrogen peroxide at various process parameters has been investigated. The optimization of the controlled parameters of the process was performed. It has been established that the highest rates of the lead dissolution process are achieved at a ratio of CH3COOH:H2O2 = 2:1. An equation is proposed to describe the dependence of the lead dissolution process on the controlled parameters, such as duration of sample processing, solution temperature, and pH level. The kinetics of lead dissolution in the mixture of acetic acid and hydrogen peroxide has been studied. The equation describing the lead dissolution process at an atmospheric pressure and temperature range of 20–96°C is obtained. A modernized technological scheme for cable scrap processing has been developed and proposed. The scheme includes process operations related to mechanical separation and sorting of the raw materials with subsequent hydro- and electrometallurgical treatment of the resulting product. Moreover, each material recovered according to the proposed scheme represents a finished commercial product. [ABSTRACT FROM AUTHOR]

This article examines a loading scheme for a sheet-mill work roll that places the roll in a plane stress state. This state is completely determined by the stresses in a ring that represents the intersection of the roll’s cross section by a plane which is perpendicular to its axis. As part of preparing data for calculation, the circumferences of the ring are divided into individual elements and the normal and shear stresses acting on these elements are calculated. Formulas are proposed for dividing the arcs that comprise the outer circumference of the ring into discrete sections and determining the average normal and shear stresses for rectilinear boundary elements. Replacing the inner and outer circumferences of the ring by polygons does not violate the conditions required for static equilibrium. An example is given to illustrate preparation of the data and its use in calculations. [ABSTRACT FROM AUTHOR]

The authors review a technology that combines the process of horizontal continuous metal casting with deformation of metal, and describes the principle of operation of the system that implements this technology. The paper provides the results of experimental studies of billets made of aluminum alloy AD1. As shown in the paper, metal products, obtained by casting into a movable wall crystallizer with simultaneous deformation of metal during solidification, have a 40% higher strength and 45% higher ductility compared to metal products obtained by using conventional technologies. The metal products obtained by using the proposed technology are characterized by a fine structure oriented in the direction of billet passing. [ABSTRACT FROM AUTHOR]

As part of the development of critical technologies, it is necessary to search for alternative replacement of components in the compositions of aluminum ligatures, including known modifying additives of scandium and yttrium with other rare-earth and rare elements. Aluminum ligatures with rare-earth metals are widely considered in many scientific papers, but the research on the production of Al-Yb ligatures is limited. In this paper, the authors describe the results of studying the production of ligatures of the aluminum-ytterbium system from ytterbium oxide by aluminothermic reduction, containing nanoscale Al3Yb intermetallic compounds and eutectics in their structure. Serving as crystallization centers, the optimal-size particles of intermetallic compounds provide uniform fine-grained structure in aluminum alloy castings. The relationship has been obtained that enables the maximum transition of ytterbium into the alloy depending on the quantitative and qualitative composition of the reaction mixture and various melting process parameters. The conducted studies have shown that ligatures obtained by aluminothermic reduction of ytterbium oxide with the addition of 5 to 15 wt. % Mg to the reaction mixture have the highest characteristic of ytterbium transition into the ligature. [ABSTRACT FROM AUTHOR]

An important problem in modern equipment is the friction between metal surfaces in various mechanisms. Friction leads to wear of rubbing parts. To reduce the friction coefficient, it is proposed to treat the surfaces of the rubbing parts with a suspension containing a high percentage (more than 20%) of ultrafine detonation nanodiamond. During such treatment, nanodiamond particles penetrate into the treated substance and create a thin surface layer (up to 1,000 nm, depending on the degree of treatment), leading to a more smooth micro-slip effect, due to which the friction coefficient decreases. The resulting surface layer consists of a metal matrix and diamond nanoparticles embedded in it. The paper shows the results of the surface analysis of a steel part using the optical and X-ray diffraction methods, and provides information about the change in the coefficient of friction of steel parts. [ABSTRACT FROM AUTHOR]

Conventional converting of nickel-containing copper mattes in Peirce–Smith horizontal converters does not conform with the current environmental regulations. A global trend is to change over from conventional batch converting to a continuous converting process producing running slags. The main purpose of the continuous matte converting process is to produce commercial blister copper that would not require oxidation during further anode refining. To minimize the risks of obtaining off-grade blister copper, the Norilsk Nickel Continuous Converting of Copper Nickel-Containing Mattes Project provides for granulation and rapid determination of the composition of converter matte using an on-stream analyzer. Currently, the matte granulation process has not been studied adequately. The objective of this paper is to study the granulation of copper–nickel mattes of variant composition under various process conditions. The effect of the granulated matte composition on water pH has been studied. Noticeable acidification of water used for melt granulation has been found out, which is probably due to the formation of soluble sulfates of non-ferrous metals and sulfuric acid. To minimize the risk of equipment wear, a method for neutralizing the process water with alkali in the granulation unit has been proposed. The time of accumulation of sodium sulfate to the solubility limit in the closed water supply cycle of the granulation unit has been determined based on the composition of granulated mattes. DTA and TGA data for granulated matte samples indicate a decrease in the equivalent diameter of matte granules with increase in the degree of superheating above the liquidus temperature. It has been established that not only the superheating of the melt, but also the pressure head of granulation water–air jet affects the degree of dispergation of the melt. [ABSTRACT FROM AUTHOR]

With its high thermal conductivity and excellent compliance with the requirements, lead-based babbitt is commonly used by manufacturers in structures to be subject to shock loading. Since some lead-based babbitt products have a uniform grain structure, they can be used under heavy loads at low constant rates. Lead-based babbitt is a low-cost alloy; therefore, it can be used for general-purpose machines, line shafting, and machine shops. It can also be used in farm machinery, cement equipment, conveyors, elevators, and metallurgical equipment. One of the most important physical properties of lead babbitt is heat capacity. The paper presents results of studying the temperature dependence of the specific heat capacity and changes in the thermodynamic functions of BLi lead babbitt (PbSb15Sn10Li) doped with lithium in the "cooling" mode in the range of 298.15 to 550 K. For this purpose, the curves of cooling rates of BLi babbitt test samples and a reference sample (lead of grade C00) were processed to derive polynomials that describe their cooling rates. Further, the experimental cooling rates and masses of the reference and test samples were used to establish the temperature dependence of the heat capacity of the alloys and the reference material, which is described by a four-term equation. Integrating the specific heat capacity led to polynomials describing the temperature dependence of changes in the enthalpy, entropy, and Gibbs energy of the alloys. The relationships obtained show that with increasing temperature and lithium concentration, the heat capacity, enthalpy, and entropy of the alloys increase, while the Gibbs energy decreases. [ABSTRACT FROM AUTHOR]

The paper provides brief information about the state of production and use of niobium in steelmaking and about niobium deposits in Russia. Pyrochlore-apatite ores contain a significant amount of phosphorus; therefore, the schemes of their enrichment include a dephosphorization stage, which reduces the niobium extraction into the product, increasing its cost. The possibility of improving the through production scheme, including the enrichment of ores and the smelting of niobium ferroalloy, is shown. The smelting process and the physicochemical characteristics of the used concentrates of the CaO– SiO2–MgO–Al2O3–TiO2–Nb2O5–Fe2O3–P2O5 system have not been sufficiently studied; therefore, thermodynamic simulation of carbothermal and metal-thermal processes of reducing the oxide system components was performed in order to determine the influence of chemical composition of the system, the amount of reducing agent and temperature on the reduction degree of elements, the composition of the metal and oxide phases, and the metal dephosphorization. Thermodynamic simulation was carried out for temperatures of 1400–1700 °C at a reducing agent consumption of 80, 100 and 120% of the stoichiometrically required amount for the reduction of the system leading elements. With the carbothermal method, the phosphorus reduction occurs quite completely at more than 100% of carbon of the stoichiometrically required amount already at 1100°C and above. With the silicothermal method, the influence of temperature and silicon amount on the reduction degree of Nb, P, Ti and the chemical and phase compositions of the alloy is shown. [ABSTRACT FROM AUTHOR]

The paper draws attention to the existing problem of the formation of a defect in the form of a carbide network in cast high-speed steels, which makes products made of such material susceptible to brittle fracture during their operation. The paper also points out high hardness of the particles of pulverized high-speed steel powders, which is why compact products made of these powders are currently obtained by a technologically complex method of hot isostatic pressing. As an alternative to such a powder, a powder mixture of R6M5K5 grade steel is considered, which contains a diffusion-alloyed spongy powder based on tungsten, molybdenum, cobalt, and iron, and can be compacted by cold pressing. A study of the structure of a billet made of such mixture and sintered at 1,000°C revealed the formation of fine-sized carbides, which takes place inside the iron matrix both between and within the grains. Such carbides have a needle-like and flaky shape. Their presence has a positive effect on the hardness of the products. The structure of a billet made of a smaller-fraction powder and sintered at 1,200°C was denser and had finer grains; however, carbides were larger in size and were located as separate inclusions in the structure. It is noted that by selecting the optimal particle size distribution of the powder mixture, compaction pressure, temperature, and soaking time during sintering and subsequent heat treatment, it becomes possible to obtain high-density blanks with fine-grained homogeneous structure. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the distribution of thickness and mechanical properties along the length and width of hot-rolled strips of electrical anisotropic steel. The results obtained contribute to understanding the reasons for the manifestation of instability in the process of subsequent cold rolling of anisotropic electrical steel strips. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental and analytical testing of the ternary Ge–In–Sn system. Experimental part includes results of the corrosion resistance, microstructure, hardness and electrical properties of the selected ternary Ge–In–Sn alloys. The prepared alloys were tested using X-ray powder diffraction (XRD) method, scanning electron microscopy with energy dispersive spectrometry (SEMEDS), hardness and electrical conductivity tests. For the obtained values of hardness and electrical conductivity, a mathematical model was used in order to determine the properties of the alloy in the entire range of the composition. The results of the Brinell hardness test show that the Ge80In10Sn10 ternary alloy has the highest hardness of all tested ternary alloys, 254.2 MN/m2. While, results of the electrical conductivity test show that the Ge10In10Sn80 ternary alloy has the highest conductivity of all tested ternary alloys and the highest corrosion resistance. Calculated isothermal section at 25°C, were confirmed with XRD and EDS results. [ABSTRACT FROM AUTHOR]

Based on experimental studies aimed at the analysis of the dimensional characteristics of electroerosive powders obtained from T5K10 hard-alloy waste in lighting kerosene, this paper presents the high efficiency of the use of electro dispersion technology, which provides, at low energy costs, the production of new powder materials of spherical and elliptical shapes suitable for industrial use. Essentially, the particles of hard-alloy powder obtained through the electro erosive dispersion of T5K10 hard-alloy waste in kerosene have dimensions from 0.25 to 125 microns with two pronounced peaks of 15 and 45 microns. [ABSTRACT FROM AUTHOR]

This paper presents the technology of producing, in vacuum arc furnaces, master alloys based on nickel and rare refractory metals (rhenium, ruthenium, and hafnium) of ReNi-1, RuNi-2, and HfNi10 grades. The technology involves the use of metal powders as initial components, which are pre-compressed into tablets and degassed in a vacuum electric resistance furnace. Though this process, an ultra-low content of gas impurities in the master alloys is provided, which increased their manufacturability when introduced into the melt and contributed to the quality improvement of the smelted cast heat-resistant nickel alloys. Alloys ZhS32, VZhM4, and VKNA-1VR, melted using the developed master alloys, have high chemical composition stability, low levels of harmful impurities and gases, and consistently high levels of mechanical properties, which comply with the requirements of technical specifications and alloy certificates. [ABSTRACT FROM AUTHOR]

The paper analyzes the results of studying the specifics of various methods for obtaining nickel aluminide (NiAl) powder. The problems hindering the widespread use of nickel aluminide (NiAl) in modern aircraft and engine construction are reviewed. It was found that the main problems preventing the widespread industrial use of nickel aluminide (NiAl) have to do with practically zero plasticity of the material during pressure treatment and difficulties associated with machining parts made thereof. However, this problem can be solved by using powder metallurgy technologies, when a practically finished product is formed that requires minimal amounts of subsequent machining. Within the framework of the conducted studies, the quality criteria of the obtained powder particles were determined, which include their sphericity, stability of the resulting particle sizes, absence of defects in the form of pores, absence of satellites on the surface of the powder particles, presence of a finely dispersed dendritic structure of the material of the obtained particles, etc. Several methods of obtaining spherical particles of nickel aluminide (NiAl) powder have been investigated in terms of obtaining the highest quality raw materials, namely: spraying the melted billet with a high-temperature inert gas flow (gas atomization method), centrifugal atomization of the melted electrode (PREP method), and melt spinning using a perforated crucible. It was determined that the optimal way to obtain high-quality NiAl powder material is the PREP method. In the course of the conducted research, it was proved that the main parameter of the process of centrifugal atomization of the melted electrode, affecting the quality of the resulting powder particles, their diameter and the value of the dendritic parameter of their microstructure, is not so much the current (I) as the rotation speed of the melted electrode (n). The optimal values of the electrode rotation speeds were determined to be as follows: n ≈ 15,000–16,000 rpm at I ≈ 1,000–1,500 A. [ABSTRACT FROM AUTHOR]

Two series of steel samples with a copper content of 0–9 wt.% were obtained. The first series is a hypereutectoid steel with varying copper content. The structure of the samples of the second series contains graphite formed as a result of modification inside the mold with 0.15 wt.% of silicocalcium. The paper shows the change in the form of graphite with an increase in the copper content in steel. Particular attention was paid to the structure of the particles of the ε-Cu phase. The study presents a scheme for the formation of a structure inside large particles of the ε-Cu phase. By reducing the solubility of iron in copper inside the ε-Cu phase during crystallization and cooling of the particles of the ε-Cu phase, the formation of three types of particles based on iron is anticipated. The results of the influence of copper on the following mechanical properties are shown: hardness, ultimate strength under uniaxial static tension and compression. [ABSTRACT FROM AUTHOR]

The paper presents the results of a project performed under the conditions of the Re Alloys plant for the production of aluminum ferrosilicon having a silicon and aluminum content equal to 55–75 and 4–20 wt%, respectively, in a six-electrode submerged arc furnace equipped with two 7.75 MVA transformers. The experience of development and incorporation of the aluminum ferrosilicon smelting technology into the industrial activity of the plant is recounted. Additionally, the paper describes the results of the work carried out within the framework of the project on the selection of charge materials, in particular, waste raw materials with a high Al2O3 content, as well as the optimization of both the charge composition and the technological mode of the submerged arc furnace in order to maximize the degree of aluminum and silicon extraction into the finished alloy. [ABSTRACT FROM AUTHOR]

Sintered parts obtained using traditional and new raw materials are widely used in the industry. The latter include partially alloyed powders. Sintering is one of the most important and complex technological operations in alloy production. The product properties depend on the correct choice of the sintering parameters. The paper discusses the growth patterns of the contact surface during sintering of powder steels, and also defines the criteria for the development of high-quality bonding depending on the sintering process conditions. [ABSTRACT FROM AUTHOR]

The paper presents a procedure for carrying out quantitative structural-phase analysis (CSFA) based on the results of X-ray diffraction studies and measurement of specific volumes. The CSFA procedure was applied to constructing the phase composition diagrams illustrating structural changes in steels due to the exposure to an external magnetic field during quenching. The changes in the phase composition and distribution of carbon, caused by the magnetic field effect, result in an increased degree of martensite decomposition according to a two-phase mechanism, occurrence of fine carbon delamination, and formation of highly dispersed carbide phase particles, leading to the creation of a structural state, characteristic of steel after an ordinary quenching and low-temperature tempering. [ABSTRACT FROM AUTHOR]

A growing demand for structural materials with a set of unique characteristics, enabling the use of products under increased mechanical loads, elevated temperatures or chemically aggressive environments, is becoming a global trend in the industry, and especially in the field of metal-intensive manufacturing. These materials include intermetallic compounds based on metal aluminides. Materials of this nature are widely used as coatings to increase the service life of the products, reduce their weight and consumption of alloying materials. However, low ductility of such materials determines their low demand for products designed for use under the impact or alternating loads. The paper analyzes advantages and dis-advantages of intermetallic materials containing aluminum, modern methods of their use, and prospects for extending their applicability for the production of new metal products. [ABSTRACT FROM AUTHOR]

Obtaining the desired characteristics of products having complex geometry from compositions comprising powdered dissimilar materials used in the formation of consumable patterns allows the scope of application of specific precision casting methods to be extended. It is established that, when forming compacts having complex configurations using a mixture of wax and water-soluble components, it is impossible to achieve the distribution of properties in the volume of the final product, which determines the change in the geometry of compacts as a result of the elastic response of compacted material. The issue associated with the elastic response of such compacted material can be solved in an experiment, establishing the influence of the initial packing and compacting parameters of wax elements on the stress-strain state of the compact. In the paper, the research results represented as experimental polynomial dependences of stress on deformation in compacted bodies with various initial packing options, deformable plastic and elastic elements, are presented. The means of controlling the dimensional and geometric parameters of the final compacts from wax model materials obtained in the process of uniaxial compaction by regulating its stress-strain state are presented. [ABSTRACT FROM AUTHOR]