Due to the constant increase in axial loads and the weight of rolling stock intended for passenger and freight heavy traffic, more stringent requirements are being put forward by consumers of rail products. The pearlite-grade carbon steels currently used for the industrial production of rails have high consumer properties, namely, resistance to wear and the formation of contact and fatigue defects, which makes it possible to ensure operability in a wide range of operational and climatic conditions along the entire length of the railway network. An important technical task is to establish the patterns of formation of the microstructure of rails depending on the chemical composition of steel and influence of the structure on properties of the finished products. One of the main parameters determining the structure and consumer properties of pearlite steel railway rails is the size of the interlamellar spacing. Improving the operational stability of rails is one of the main tasks of the specia­lists of JSC EVRAZ ZSMK, the Kuzbass Metallurgical Plant, one of the five largest manufacturers of railway rails in the world. The results of a comparative analysis of chemical composition, size of the interlamellar spacing, as well as the strength and plastic properties of the metal of pearlite-class railway rails are presented. In accordance with GOST R 51685-2022, 90KhAF steel is hypereutectoid in terms of carbon content. As a result of the conducted research, the relationships between parameters of the structure and the physico-mechanical properties of rails, as well as between content of the main chemical elements in steel and the interlamellar spacing of perlite, were established.

The use of investment casting process is aimed at producing castings of complex configuration with increased dimensional and geometric accuracy from a wide range of casting steels and non-ferrous alloys. A number of operations during the implementation of such a process are accompanied by the appearance of defects of a thermophysical nature (shrinkage of the pattern material and its thermal expansion during melting, leading to a violation of the ceramic mold integrity), which, to a certain extent, prevents the expansion of the casting nomenclature. The formation of experimental porous investment patterns by compaction of powders of waxy materials is aimed at eliminating such defects, but, due to the lack of information on the processes accompanying the compaction of waxy powders (in some cases manifested in the elastic response of the material or a change in the strength characteristics of the compacts), requires separate study. It was previously established that the distribution of density values in a paraffin powder compact is provided by directional loading of the compacted material, including in the field of centrifugal forces, which allows obtaining the surface configuration of a body of revolution with a predictable distribution of properties in each of its sections. In this paper, using the example of forming a section of a body of revolution, a comparison is given of the calculated and experimental dependencies of the relative density of compacts (obtained from different fractions of the PS50/50 material) on the stresses arising during their compaction in the field of centrifugal forces, as well as the average values of the density of compacts on the molds rotation speed. Pictures of the stress-strain state of compacts are presented when determining the values of their compressive strength characteristic of various waxy materials. The results of the experiment are aimed at solving the problems of increasing the efficiency of processes for obtaining investment patterns, the configuration of which is a body of revolution, formed by compaction of powdered waxy materials in the field of centrifugal forces.

Starting in 2018, JSC EVRAZ United West Siberian Metallurgical Plant (EVRAZ ZSMK) produced rails of the DT400IK category with increased wear resistance and cyclic crack resistance for heavy traffic and difficult sections of track with steep curves with a radius of less than 650 m. The method of transmission diffraction electron microscopy was used to study the structural and phase states and defect substructure at different distances (0, 2, 10 mm) from the “wheel – rail” contact surface along the central axis of symmetry of the rail head (tread surface) and along the radius of rounding of the rail head (fillet) of differentially hardened long rails of the DT400IK category made of hypereutectoid steel after long-term operation on the experimental ring of Russian Railways (passed tonnage of 187 million tons). Based on the obtained structure parameters, the quantitative estimates were made of the dislocation substructure and main strengthening mechanisms (strengthening of the pearlite component, incoherent cementite particles, grain boundaries and subboundaries, dislocation substructure and internal stress fields) in various morphological components and in the material as a whole, forming the additive yield strength in the studied steel. A comparison of the quantitative parameters of the fine structure and contributions to strengthening on the tread surface and fillet was carried out. It was established that near the “wheel – rail” contact on the tread surface the prevailing morphological component is the subgrain structure, in the fillet – a ferrite-carbide mixture (completely destroyed pearlite). Strength of the rail head metal depends on the distance to the “wheel – rail” contact surface. It is shown that the main streng­thening mechanisms on the tread surface are strengthening by internal stress fields, in the fillet – strengthening by incoherent particles.

The work is devoted to the study of the possibility of obtaining carbide steel based on powdered high-speed steel 10R6M5 with additives of tungsten (WC) and titanium (TiC) carbides by induction surfacing. The selected compositions of the deposited charge and the proposed composition of the flux based on fused borax with additives of boric acid and a number of oxides satisfy the technology. The developed technology includes a flux, a method of briquetting charge using a piston device that minimizes the movement of ferromagnetic components of the charge under the influence of inductor electromagnetic field during surfacing. Deposited layers of carbide steel based on high-speed steel reinforced with tungsten and titanium carbides were produced and studied. The obtained layers were analyzed using optical and electron microscopy (using a microanalyzer), phase composition of the deposited layers was controlled by the X-ray phase method, and hardness of the layers was measured by the Rockwell method. Addition of tungsten carbide to powdered high-speed steel leads to the formation of ledeburite structure during surfacing, which is characteristic of high-tungsten high-speed steels. An increase in the amount of tungsten carbide in the carbide steel leads only to its partial melting in liquid steel, which helps to preserve the particles of introduced carbides in the microstructure. Titanium carbide added to the carbide steel composition significantly changes the morphology of ledeburite precipitates. According to X-ray phase analysis data, a number of carbides of Me₁₂C, Me₆C, Me₂C and MeC types were observed in the composition of carbide steels, which are characteristic of carbide steels obtained by various methods (plasma surfacing, sintering, impregnation of a carbide frame, etc.). It is shown that hardness of the samples of carbide steels with additives of tungsten and titanium carbides varies from 59 to 63 HRC, depending on the composition and technological modes of surfacing.

The authors studied the tribotechnical behavior of C235 steel under conditions of dry sliding electrical contact with a current density of more than 100 A/cm² at different transformation coefficients of the supply transformer. A decrease in the transformation coefficient leads to a decrease in the wear resistance and electrical conductivity of the contact. Metallographic methods revealed the formation of transfer layers on the contact surfaces. Thickness of the transfer layers does not exceed 20 μm. Morphological patterns of worn contact surfaces on the scale of the nominal (geometric) contact area consist of two sectors, where one sector has signs of melting. X-ray phase analysis has shown that the transfer layers contain more than 70 vol. % FeO. That is why the transfer layers could be represented as a quasi-dielectric medium, where FeO acts as a dielectric. The authors assume that strong self-induction pulses occur in the contact zone, which cause high-density displacement currents. These currents act directly on FeO ions and convert them into a melt. These concepts allow us to assert that the melt consists of atoms or ions of iron and oxygen. A decrease in the transformation coefficient (that is, an increase in the inductance of the secondary winding of the supply transformer) causes an increase in self-induction pulses and displacement currents, which leads to an increase in the amount of FeO melt, its easy removal from the contact area, and a corresponding decrease in the wear resistance and electrical conductivity of the contact. The data obtained can serve as guidelines when choosing wear-resistant materials for high-current sliding contact and, in particular, when defining its design.

Special-purpose alloys based on the Al – Si – Cu system are widely used in various industries, including engine and instrument engineering. The effect of annealing in the range of 100 – 900 °C on microstructure, density, and microhardness of Al – 30 % Si – 50 % Cu alloy was studied. Scanning electron microscopy showed that as the annealing temperature increases, the form of eutectic silicon particles changes and their coagulation occurs. According to the results of microrentgenospectral analysis, change in the eutectic structure is accompanied by segregation of copper in its individual sections. After annealing, there is a slight decrease in density and microhardness of the alloy.

The problem of differences in surface quality exists in the production of amorphous alloy (AA) ribbons by ultra-fast single-roll melt spinning. Structural inhomogeneities that can disrupt the isotropy of properties occur on the side of the ribbons adjacent to the quenching drum. In this regard, there is a need to develop a promising surface modification technology of AA which will not only eliminate roughness, but also controllingly manage the structure along the ribbon depth, as well as selective processing of its individual sections to improve mechanical, magnetic and catalytic characteristics. Application of short-pulse laser systems has great potential for achieving these goals. In this research work, the effect of an excimer ultraviolet laser operating in nanometer wavelength range on the structural evolution, mechanical behavior and morphological changes of the surface of Fe_53.3Ni_26.5B_20.2 AA with varying the pulse number and their frequency were comprehensively studied using profilometry, indentation, optical and transmission electron microscopy methods. It is shown that laser irradiation of the contact matte side of the studied AA ribbon according to the selected mode (100 pulses, f = 20 Hz, E = 150 mJ, W = 0.6 J/cm²) effectively acts upon the surface relief and smoothes out production irregularities (pores, gas lines, scratches, etc.). In addition, the laser processing parameters are established that contribute to the AA structure softening, and therefore improve workability for possible forming, as well as the mode of transfer AA to an amorphous-nanocrystalline state with increased hardness and preservation of the ability to flow shear.

The paper is intended for researchers studying of supercooled metallic melts. It addresses an important theoretical problem: the possibility of establishing local thermodynamic equilibrium at the phase boundary during crystallization from a supercooled melt. Such processes play a crucial role in determining the microstructure of materials during solidification, particularly under rapid cooling conditions characteristic of modern metallurgical and powder technologies. During supercooling, nuclei of a new, solid phase begin to form in the melt. To mathematically describe the growth of such nuclei, it is necessary to specify boundary conditions that define the composition of the adjacent liquid phase. Traditional models assume that local equilibrium can be established near the nucleus and that its parameters can be derived from the equilibrium phase diagram. However, as demonstrated by our study of binary systems, local equilibrium may, in some cases, be fundamentally unattainable. This article presents a theoretical analysis of the conditions under which equilibrium may or may not be established. The analysis considers chemical potentials of the components in both the solid nucleus and the liquid melt. Based on the equilibrium phase diagram of the corresponding macrosystem, one can infer the relative chemical potentials of the components in each phase. It is shown that when the nucleus consists of a single component, local equilibrium is always possible in principle. However, when the nucleus is a solution, equilibrium may only be realized under specific thermodynamic conditions. In such cases, the application of first-kind boundary conditions becomes invalid, and it is necessary to take into account the rates of chemical reactions involved in the interphase transfer of each component.

During the crystallization of liquid metal in a shell casting mold, significant normal stresses occur on its surfaces. On the inner – compressive, on the outer – tensile. They are especially pronounced at the initial moment of cooling time. This can lead to damage to the casting mold, and hence damage to the crystallizing metal casting. It is possible to reduce the level of stress-strain state in the surface layers by applying special annular (temperature) recesses (seams) to the outer and inner surfaces. In this paper, the problem of the influence of temperature seams in inner and outer layers of a shell mold (SM) on the level of its stress-strain state (SSS) during crystallization of a steel casting was formulated and solved. The normal stresses σ₂₂, σ₃₃, which occur both on the inner and outer surfaces of SM at the initial moment of metal casting and cooling of the steel casting, are accepted as a parameter of SM resistance to cracking. An axisymmetric problem for a cylindrical ceramic SM is considered. Based on the formulated objective function, the paper presents an algorithm for solving the problem using the equations of the linear theory of elasticity, the equation of thermal conductivity and the proven numerical method. As a result of solving the problem, the minimum number and locations of recesses on the inner and outer surfaces of SM, ensuring a decrease in normal stresses, were determined. The results of solving the problem are presented in the form of stress plots across the sections of the considered area. The authors analyzed the obtained results of SM resistance to cracking and gave recommendations on the use of the obtained results in various scientific and technical fields.

The article solves the problem of determining thermoelastic stresses in calibrated strikers in a unit of combined casting and deformation during production of hollow steel billets using the calculation methodology developed by the authors. The authors substantiate the relevance of determining thermoelastic stresses in insulated strikers when compressing the wall of a hollow billet and at idle run when cooling the strikers with water, and describe the striker geometry to produce a hollow billet in one pass. The paper considers the initial data and temperature boundary conditions for calculating the temperature field of the striker during production of hollow billets in a unit of combined casting and deformation. The boundary conditions are given to determine the striker temperature as well as the values of heat flow and effective heat transfer coefficient. The results of calculating the temperature fields are performed in four sections and are presented for characteristic lines and points located on the striker contact surface and in the contact layer at a depth of 5 mm from the working surface. Dimensions of the finite element grid are given to calculate thermoelastic stresses in calibrated strikers using the finite element method with ANSYS package. The authors determined the magnitudes and patterns of distribution of thermoelastic stresses in a calibrated striker when compressing the wall of a hollow billet and at idle run when such a billet is produced in one pass in a unit of combined casting and deformation. Based on the calculated temperature values and the magnitude of the maximum compressive thermoelastic stresses on the contact surface of the strikers, it is proposed to use a pipe billet as a material for making strikers.

The authors investigated the microstructure and mechanical properties of the samples obtained by the method of wire electron beam additive manufacturing (WEBAM), and their machinability by milling forces using the Taguchi method. Grains of previous austenite and annealed martensite were observed in the samples in various directions. The grains of the previous austenite grow along the surfacing direction and exhibit a pronounced orientation. On the lateral surface of the sample, the grains of the previous austenite are columnar, their hardness is approximately 505 HV_0.1. On the upper surface of the sample, the grains of the previous austenite are isometric, their hardness is approximately 539 HV_0.1. The degree of transformation into martensite varies in different parts of the sample. In the part close to the lateral surface, martensite is shallower and the previous austenitic grain boundaries are not observed. Its hardness is approximately 514 HV_0.1. In the lower part of the sample, due to multiple thermal cycles, martensite decomposes, while its hardness is low and is approximately 480 HV_0.1. In the upper part of the sample, martensite and the previous austeni­tic grain boundaries are observed, the hardness is approximately 513 HVelectron beam additive manufacturing, microstructure, hardness, machinability, martensitic stainless steel, Taguchi method. Due to the high hardness of the sample during climb milling, a stronger impact of the cutting edge on the sample leads to an increase in cutting force. Due to the low plasticity of the sample during conventional milling, a decrease in the volume of material pressed into the back surface of the tool leads to a decrease in cutting force. As the feed rate to the tooth increases, deformation of the material increases, the temperature increases, which leads to a decrease in the material strength. Reducing the material strength slows down the growth of cutting force.

Development of metallurgy provides for further increase and improvement of steel production volumes through the introduction of various advanced resource- and energy-saving technologies. The main and most universal control actions that affect the course and technical-economic indicators of the process are inextricably linked to the optimization of technology parameters which is focused on achieving the best results in the field of productivity, product quality and reduction of resource costs. This is achieved through the regular monitoring and analysis of key indicators, as well as making necessary adjustments to process management. A successful combination of these factors contributes to maximizing the production efficiency and increasing the competitiveness of products on the market. To calculate the process static parameters, it is advisable to use the resources of mathematical modeling and development of an instrumental system. When creating a static calculation model, the electric steelmaking process was considered as a complex thermodynamic system into which condensed and gaseous input media enter, and the final products are metal, slag and gas. Calculation of the static modes of the electric steelmaking process is carried out on the basis of calculations of material and thermal balances based on the laws of mass and energy conservation relative to the components of a heterogeneous system. The solution of the optimization problem based on formal methods involves selection of various criteria and setting a system of restrictions (requirements for metal composition; ranges of change in the cost of components of charge materials and system state parameters; compliance with the law of mass conservation at the level of fluxes, substances and elements; compliance with the law of energy conservation). A feature of the developed method of mathematical modeling and optimization of the electric steelmaking process is the systematic solution of a set of interrelated optimization problems to determine the optimal conditions for the processes in the metallurgical system and the optimal solutions for implementation of electric smelting technology.