International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this paper, a comprehensive analysis of the process of natural gas reform in MIDREX technology was carried out, which was aimed at optimizing this process in order to increase hydrogen yield, reduce the specific consumption of natural gas and minimize the risks of soot formation. The paper also calculates the thermal balance, combined steam-carbon dioxide reforming (SMR + DRM). Based on the conducted studies, optimal reforming modes were determined: gas outlet temperature ~915-920°C; H2O/C ~1.8; increased CO2 fraction. Switching to an optimized reforming mode reduces natural gas consumption by 5.5%, increases H2 output by 6.4%, and reduces CO2 emissions due to better energy efficiency and H2 addition potential. The results obtained in this work are useful for upgrading existing Midrex installations in the direction of decarbonization, including the transition to MIDREX Flex/H2 technologies.

This work is devoted to the development and research of a new technology for processing bar scrap from 40X steel to obtain high-quality finished metal products in the form of a screw reinforcement profile. The developed technology included two stages. At the first stage, the round-section bar scrap is formed on a radial-shear rolling mill to obtain conventional bars of the desired diameter and create initial conditions for the formation of an ultrafine grained gradient structure in the resulting screw profile. The second stage is the direct production of a screw profile with a gradient ultrafine-grained structure on a combined installation. Metallographic studies have shown that after the implementation of the second stage of obtaining a screw reinforcement profile, a gradient structure is observed in 40X steel, with equiaxed grains, the size of which lies within 1.2-1.4 μm in the peripheral region and to a greater extent with elongated, directional-oriented grains in the central region of the resulting reinforcement.

Despite the rapid development of metallurgical processes for the production of semi-finished products aimed at improving the modes of smelting, casting and crystallization, a significant improvement in the properties of any cast metal, ensuring its wide application in modern mechanical engineering, is achieved by combined thermomechanical processing of workpieces, combining hot metal forming and heat treatment. The technologies and equipment currently used in Kazakhstan by machine-building manufacturers have long been obsolete and ineffective. A common problem for everyone is the high energy intensity of production, its low productivity and the quality of forgings and blanks produced, which leaves much to be desired. Namely forgings and blanks are the starting materials for the manufacture of highquality tools and technological equipment at mining and metallurgical engineering enterprises. Therefore, the purpose of this work is to develop rational modes of thermal and thermochemical processing of 5KHV2S steel, previously forged in a tool that implements alternating strain in metal, as well as to study the influence of combined thermomechanical processing modes on the mechanical properties of this steel. The studies carried out in this work on the hardness of 5KHV2S steel samples subjected to combined thermomechanical processing showed that the developed technologies contributed to an increase in both total and surface hardness compared with samples not subjected to preforging in a new forging tool that implements alternating strain in the metal.

This work is devoted to the study of a new technology for processing bar scrap – a precision shaft made of Cf53 structural steel (DIN 17212) that has proven its service life and produces high-quality finished metal products in the form of a screw reinforcement profile. The precision shaft used for recycling of its proven service life included two stages: preliminary deformation of the shaft on a radial shear rolling mill to obtain rods of the required diameter and create initial conditions for the formation of a gradient ultrafine-grained structure in the resulting screw profile; direct production of a screw profile with a gradient ultrafine-grained structure on a combined installation. The conducted research has shown that the new combined technological process of rolling bar scrap is feasible in practice and makes it possible to obtain a high-quality finished product from this scrap in the form of a screw reinforcement profile with a gradient ultrafine-grained structure.

Despite the rapid development of metallurgical processes for the production of semi-finished products aimed at improving the modes of smelting, casting and crystallization, a significant improvement in the properties of any cast metal, ensuring its wide application in modern mechanical engineering, is achieved by combined thermomechanical processing of workpieces, combining hot metal forming and heat treatment. The technologies and equipment currently used in Kazakhstan by machine-building manufacturers have long been obsolete and ineffective. A common problem for everyone is the high energy intensity of production, its low productivity and the quality of forgings and blanks produced, which leaves much to be desired. Namely forgings and blanks are the starting materials for the manufacture of highquality tools and technological equipment at mining and metallurgical engineering enterprises. Therefore, the purpose of this work is to develop rational modes of thermal and thermochemical processing of 5KHV2S steel, previously forged in a tool that implements alternating strain in metal, as well as to study the influence of combined thermomechanical processing modes on the mechanical properties of this steel. The studies carried out in this work on the hardness of 5KHV2S steel samples subjected to combined thermomechanical processing showed that the developed technologies contributed to an increase in both total and surface hardness compared with samples not subjected to preforging in a new forging tool that implements alternating strain in the metal.

One of the effective ways to control the properties of copper is to refine its structure to a nano- or ultrafine-grained level, and primarily with the help of severe plastic deformation. At the same time, radial-shear rolling is one of the promising methods for obtaining long-length rods with a gradient ultra-fine-grained structure. It is known from a number of scientific works that one of the main factors influencing the possibility of obtaining an ultrafine-grained structure in various ferrous and non-ferrous metals and alloys is the deformation temperature of these metals and alloys. The aim of the work is to study the influence of the deformation temperature at the radial-shear rolling mill on the microstructure evolution of copper. The following deformation temperatures of copper rods were selected for the planned studies: 20°C, 100°C and 200°C. The conducted studies have shown that the implementation of radial-shear rolling at ambient temperature compared with rolling at temperatures of 100°C and 200°C made it possible to achieve more intensive refinement of the initial structure. And first of all, this is due to the fact that with radial-shear rolling of copper, realized at ambient temperature, there are no dynamic return processes.

The paper presents the results of microstructural studies of 16MnCrS5 steel hypereutectoid structure subjected to reforging under pulsating contact stress loading. It is revealed that the local evolution of the structure in the focus of contact loading has signs of selfimprovement with the transformation of the isotropic morphology of the carbide phase into an anisotropic one with signs of textural riveting. Instead of the initial structure with a uniform carbide phase distribution, signs of textural anisotropy with reinforcement elements of the modified layer high-carbon hypereutectoid zone with carbide inclusions are formed.

One of the effective ways to control the properties of copper is to refine its structure to a nano- or ultrafine-grained level, and primarily with the help of severe plastic deformation. At the same time, radial-shear rolling is one of the promising methods for obtaining long-length rods with a gradient ultra-fine-grained structure. It is known from a number of scientific works that one of the main factors influencing the possibility of obtaining an ultrafine-grained structure in various ferrous and non-ferrous metals and alloys is the deformation temperature of these metals and alloys. The aim of the work is to study the influence of the deformation temperature at the radial-shear rolling mill on the microstructure evolution of copper. The following deformation temperatures of copper rods were selected for the planned studies: 20°C, 100°C and 200°C. The conducted studies have shown that the implementation of radial-shear rolling at ambient temperature compared with rolling at temperatures of 100°C and 200°C made it possible to achieve more intensive refinement of the initial structure. And first of all, this is due to the fact that with radial-shear rolling of copper, realized at ambient temperature, there are no dynamic return processes.

The article describes the concept of a new forging method of circular cross-section blanks in a forging tool, the design of which makes it possible to develop significant alternating deformations in the deformable metal. The results of comparative studies of the microstructure and mechanical properties of AISI-5140H low-alloy structural steel, formed in a new forging tool that implements alternating deformation and in flat strikers are presented.

This work is devoted to the study of the internal defect closure during metal broaching in step-wedge strikers with wedge and depression by FEM in Deform program. A through cylindrical hole with a diameter of 3 mm was considered as an internal defect. At the same time, three variants of the defect vertical location were modeled – in the workpiece center, near the upper face of the wedge and near the lower face of the depression. In all three cases, the internal defect closure is uneven. The most intense defect closure is observed when it is located in the workpiece axial zone. Defects located near the strikers surface zones are not closed well enough. The stress-strain state analysis showed that the defect location affects the distribution nature of stresses and strains along the workpiece section.

A computer simulation of the broaching of the workpiece in step-wedge-shaped strikers of the first and second configurations was carried out by the finite element method. The comparison was made according to the following parameters of the stress-strain state: equivalent strain, average hydrostatic pressure, damage criterion, as well as the deformation force. A comparative analysis of the stress – strain state showed that the second configuration of step-wedge-shaped strikers is the most optimal option for implementing the process of broaching rectangular or square blanks. When using them, a more uniform distribution of the stress state is realized, the deformation processing is sufficiently realized in comparison with the broaching in step-wedge-shaped strikers of the first configuration

The creation and calculation of computer models of various products under load with the properties of UFG materials in the normal and irradiated state was performed. To model the UFG properties of non-irradiated AISI-321 steel, hardening curves were constructed based on the Hall-Petch equation for the base state of the material at a grain size of 1500 nm and for two UFG states (with grain sizes of 700 and 200 nm). To simulate the properties of irradiated AISI-321 steel, plastometric tests were performed using uniaxial compression of cylindrical samples at constant values of the strain rate of 1 s-1 and the temperature of 20°C on the “Gleeble 3800” plastometric unit. Fast neutron fluence with the following values was selected as a variable parameter: 0.5∙1018 n/cm2, 1∙1018 n/cm2, 0.5∙1019 n/cm2, 1∙1019 n/cm2. The maximum operating pressure of 340 MPa was used as a static load. The simulation results showed that for both parts, the use of the material in the UFG state is the most appropriate solution.