No 2 (2025)
Materials science in mechanical engineering
METAL SCIENCE RESEARCH AIMED AT CHOOSING A FOREIGN STEEL ANALOGUE FOR A RACING CAR SUSPENSION MEMBER
Abstract
The relevance of the study is due to the need to solve the problem of import substitution of materials in the automotive industry. The article presents the results of metal research aimed at choosing a foreign steel analogue for the manufacture of suspension parts of a Formula Vostok racing car. The complex of studies included chemical and metallographic analysis, tensile strength tests and hardness measurements. To determine the permissible loads occurring in the suspension guide device members, the method of analyzing the stress-strain state of the loaded assembly with the construction of a 3D model is applied. As a substitute for Italian homologated steel for the manufacture of the suspension guide element, the 20X domestic steel was determined to be the closest in chemical composition. The differences in the properties of the original steel and the substitute steel are related to the peculiarities of their microstructure: high strengthening level of the original steel results from the smaller grain size. Heat treatment in the form of quenching and high tempering (improvement) makes it possible to obtain in 20X steel the strength and hardness closest to the original, with higher ductility.
Science intensive technologies in mechanical engineering. 2025;(2):3-10
3-10
STRUCTURAL AND PHASE TRANSFORMATIONS, MASS TRANSFER, AND TRIBOTECHNICAL CHARACTERISTICS OF GAS-DYNAMIC COPPER-ZINC COATINGS OCCURRING UNDER SLIDING FRICTION
Abstract
The effect of the coating temperature and the displacement of the spray nozzle on the structural and phase transformations in the coating on 40X steel obtained by cold gas-dynamic spraying of a powder mixture of Cu:Zn: Al2O3=35:35:30 (wt%) has been studied. The phase composition of the coating was identified using the method of local X-ray spectral analysis. It was shown that under gas-dynamic spraying there can be five phases garadually occurring in the coating, being formed as a result of solid state transformations under conditions of high-speed impact contact interaction: α - Cu-Zn solid solution; βʹ - CuZn-based solid solution; γ - Cu5Zn8-based solid solution; ε -CuZn3-based solid solution.; η is a solid solution of Zn-Cu. Under sputtering temperatures of 2700and 3600 C, the alpha - Cu-Zn solid solution phase becomes predominant. Tribotechnical tests of a pair of reversible sliding friction steel 40X (coated) – steel SHX15 in an I-20A oil medium have shown that the coupling has high performance at contact pressures of at least 50 MPa. Deformation, diffusion and frictional mass transfer in the zone of contact interaction lead to the realization of the "classical wearlessness" effect, the distinctive feature of which is the formation of a copper-zinc third body with corundum inclusions and capable of direct and reverse coating transfer, providing protection of the surface layers of the friction pair from destruction High wear resistance of the friction pair contacting materials is achieved due to the frictional mass transfer films.
Science intensive technologies in mechanical engineering. 2025;(2):11-22
11-22
Technology and equipment of metal processing by pressure
UPPER BOUNDARY CALCULATION OF ISOTHERMAL YIELD OF A RING BLANK
Abstract
High-strength materials are pressure-treated under isothermal conditions with heating using a hydraulic forging equipment. At the same time, along with strainer- hardening, the workpiece material exhibits viscous properties, i.e. it is viscoplastic. This factor must be taken into account when developing pressing technology, since the power modes of stamping and the maximum possibilities of shaping depend significantly on the speed of the operation. A yield with heating of a ring blank under viscoplastic conditions is viewed. The relations for calculating the force and deformation modes of a ring blank yield under the axial symmetry scheme are proposed. The energy method of balancing the capacities of internal and external forces was used to calculate the power regime. Coulomb's law of friction is adopted on both: tool contact surfaces and the ring blank. The internal force capacities were calculated in the deformation block and on the fracture surfaces of the displacement velocities in accordance with the selected kinematically possible velocity field, including the friction surfaces. The optimization of the velocity field was carried out according to the principle of minimum operating pressure. The assessment of the damage to the material of the blank is carried out according to the energy and deformation criteria of destruction. The calculated results of the yield force and material damage for high-strength aluminum and titanium alloys are presented. It is shown that under isothermal yield of a ring blank, the force decreases at low operating speeds. The damage rate of a number of materials, the behavior of which is described by the energy theory of destruction, decreases with a decrease in the speed of the operation. For materials subject to the deformation theory of fracture, the rate of deformation has no effect on damage, but is determined only by the degree of deformation.
Science intensive technologies in mechanical engineering. 2025;(2):23-29
23-29
Technologies of mechanical processing of workpieces
ABRASIVE WEAR PRODUCTS TRANSPORT DURING TITANIUM SCRATCHING AND ABRASION
Abstract
Buried abrasive tool wear products on the surface of critical titanium alloy products become a fatal defect that can significantly reduce the service life of the unit due to intense abrasive wear of the contacting surfaces and the formation of fatigue cracks. Using the example of single grain cutting, it is shown that as a result of micro-piercing of an abrasive material, metal transport to the contacting surfaces of the grain decreases and wear products are introduced into the treated surface. When grinding with tools made of superhard materials, the possibility of monitoring and controlling this process by X-ray spectral analysis is limited resulting from a significant error in determining small concentrations of light elements. In order to measure the parameters of the wear products transport of an abrasive material, a method based on the analysis of polished surfaces images obtained in backscattered electrons is proposed. Based on the results of the elemental analysis, the composition of the wear products and the measurement errors of the transfer parameters under grinding with silicon carbide and cubic boron nitride (CBN) wheels, namely the number and area of buried particles, were determined. The share of structured crystals of abrasive materials for silicon carbide wheels is 80% and for CBN disks is 70%, including 20% corundum crystals (filler).
Science intensive technologies in mechanical engineering. 2025;(2):30-39
30-39
Technologies of electromachining and combined processing
PROBLEMS AND SOLUTIONS OF COMPOSITE MACHINING BY ELECTRO-DIAMOND METHODS FOR MATERIALS BASED ON ZIRCONIUM DIBORIDE
Abstract
Problematic issues related to the development, machinability and application of new high-strength ceramic materials are viewed. Such materials possess high hardness comparable to the hardness of abrasive materials. Therefore, it makes difficult to produce such materials using traditional techniques. To solve this problem, we have proposed the modernization of the PP 600F machine with the implementation of combined electro-diamond processing of high-strength ceramic materials with diamond wheels on a binder metal. The modernization provides for the development of special components and structures of a current collector, a cathode for straightening a circle, a circuit for a technological current source and constructive solutions for automatic control of the straightening current. Based on the results of the study, rational cutting modes have been established to guarantee the quality of products made of high-strength composite materials. The experiments were performed with standard techniques using optical and electron microscopy. The tasks were solved taking into account the study of diamond wheels flow density on a metallic binder, as well as forces, power, cutting temperature, defects on the surface of the grinding wheel and the machined product. The solution for controlling the cutting capacity of a grinding wheel and the conditions of their operation in the self-sharpening mode is shown. Based on the stabilization of cutting power, the self-sharpening mode of diamond wheels on a metallic binder and grinding modes are switched on:Vgwh = 35 m/s; Spr = 0.5.1.5 m/min; Spr = 0,5…1,5 m/min; Spop = 0,02…0,05 mm/dv.stroke ipr = 0,2…0,6 A/cm2; itr = 4…6A/cm2. Using the example of grinding zirconium diboride with an A C 6 diamond wheel with a grain size of 125/100 in these modes, it guarantees the absence of micro, macro cracks, and the roughness of the machined surface within 0.2…0.4 microns.
Science intensive technologies in mechanical engineering. 2025;(2):40-48
40-48