Obrabotka Metallov / Metal Working and Material Science
ISSN (print): 1994-6309, ISSN (online): 2541-819X Founders: Novosibirsk State Technical University; Limited Liability Company Novosibirsk Scientific-Production Commercial Firm "Mashservispribor" Editor-in-Chief: Anatoliy A. Bataev, Doctor of Sc. (Engineering), Professor Frequency / Access: 4 issues per year / Subscription Included in: White List (3rd level), Higher Attestation Commission List, RISC, Scopus, Web of Science Core Collection
Новосибирский государственный технический университет
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Machining performance evaluation of eco-friendly copper oxide-based nanofluids in turning operations
Introduction. There is a growing demand for eco-friendly cutting fluids in machining due to their non-toxicity, sustainability, high performance, and ability to improve surface quality. These fluids support green manufacturing practices and promote a safe working environment. Copper oxide-based nanofluids offer the combined benefits of enhanced heat transfer, increased safety, and reduced tool wear and cutting forces. The purpose of the work. This research focuses on evaluating the performance of copper oxide-based cutting fluids in turning processes to support sustainable and eco-conscious manufacturing. The study investigates the turning of SS 304 steel using varying concentrations of copper oxide nanofluids. The methods of investigation. In this study, the turning process was tested under various machining conditions using different concentrations of copper oxide nanoparticles (0.3 %, 0.6 %, 0.9 %, 1.2 %, and 1.5 %). Corn oil was selected as the base oil, and the copper oxide nanoparticles were dispersed in the corn oil to prepare the nanofluid. Machining trials were conducted under different lubrication environments: dry, wet, minimum quantity lubrication (MQL), and nano-enhanced MQL (nMQL). A comparative study was performed to assess cutting temperature and cutting forces. Results and discussion. The results showed that the use of 1.2 % copper oxide nanofluid led to significant reductions in cutting force and cutting temperature, by approximately 17.54 % and 29.53 %, respectively, compared to traditional dry and wet machining environments. Furthermore, the nanofluid was observed to form a protective film at the tool-workpiece interface, reducing tool wear. These findings highlight the potential of copper oxide-based green cutting fluids to improve turning operation efficiency and promote environmentally sustainable practices.
Copyright (c) 2025 Manikanta J.E., Ambhore N., Murthy K.B., Thellaputta G.R., Agrawal D. https://creativecommons.org/licenses/by/4.0
Research and analysis of electrical discharge machining in the manufacture of products from heat-resistant alloys: a literature review
Introduction. In modern mechanical engineering, there is a growing trend toward the development and implementation of novel heat-resistant alloys with enhanced physical and mechanical properties. Electrical discharge machining (EDM) is a promising method for manufacturing products from these new-generation heat-resistant alloys. This paper presents an analysis of current research in the field of EDM of heat-resistant alloys. The primary focus is on analyzing output qualitative and quantitative indicators in relation to input parameters — machining mode and conditions. The key factors influencing the efficiency of EDM are considered, including machining parameters and the composition of the working fluid and electrode material. This analysis of current research is intended for specialists in the field of heat-resistant alloy machining, developers of EDM technologies, and researchers working to improve manufacturing methods for aircraft engine components. The purpose of this work is to conduct a literature review of existing research on modern methods for ensuring and improving the efficiency and quality of electrical discharge machining (EDM) of heat-resistant materials. The methods of investigation involved a theoretical analysis of current research on electrical discharge machining of heat-resistant alloys. Results and discussion. A literature analysis was conducted, and it revealed that current strength and pulse duration are the main technological parameters determining the quality of the processed surface and the material removal rate. The effectiveness of using modified working fluids (with graphene and carbon nanotubes) during heat-resistant material processing to improve surface quality was confirmed. It is of particular interest to conduct experimental studies on the influence of adding various material components to the working fluid to improve surface quality indicators after complex pulse electrical discharge machining (CPEDM) and to assess the impact of these alloying materials on the surface layer of heat-resistant materials.
Copyright (c) 2025 Shlykov E.S., Ablyaz T.R., Blokhin V.B., Muratov K.R., Osinnikov I.V. https://creativecommons.org/licenses/by/4.0
ANFIS modeling of turning Al7075 hybrid nanocomposites under compressed air cooling
Introduction. Hybrid metal matrix composites (HMMCs) are increasingly used in the aviation and automotive industries due to their low density, high stiffness, and exceptional specific strength. Among aluminum MMCs, Al7075-based composites are gaining wider acceptance. Continuous research and development in this field focuses on improving the durability and performance of these advanced materials. Purpose of the work. Machinability of Al7075 is a significant challenge because the abrasive reinforcement phase causes rapid tool deterioration, increased machining forces, and a poor surface finish. Moreover, the industrial focus on green manufacturing has led to a shift from traditional coolant-based machining to sustainable alternatives. In this context, researchers have optimized machining performance using advanced technological advancements and techniques. However, limited work is reported on modeling the machining performance of Al7075 nanocomposites during turning under compressed air cooling. Methods of investigation. Manufacturers can gain a better understanding of increasing the effectiveness of turning processes for Al7075 nanocomposites by creating a comprehensive model. Therefore, this work models the machining performance of hybrid Al7075 nanocomposites during turning under compressed air-cooling conditions with an artificial neuro-fuzzy inference system (ANFIS) to predict tool wear (TW), surface roughness (Ra), and cutting force (Fc) as a function of process parameters. Results and discussion. In this work, an ANFIS model was developed to predict the machining performance considering the effect of process parameters such as cutting speed, feed rate, and depth of cut for different Al7075-based nanocomposites. These nanocomposites were prepared using silicon carbide (30–50 nm) and graphene (5–10 nm) nanoparticles as reinforcements by the stir casting process. Reinforcement materials affect the mechanical and physical properties of composites. For engineering applications, SiC and graphene are preferred reinforcements with distinctive features. ANFIS models were developed to predict Ra, Fc, and TW based on the experimental results. The Sugino method was used to represent fuzzy rules and membership functions, as it utilizes weighted averages in the defuzzification process and offers better processing efficiency. The MATLAB ANFIS toolbox was used to design and tune fuzzy inference systems. The developed ANFIS model predicts machining responses effectively and offers a practical approach for optimizing process parameters with high reliability. The results of this research show good agreement between the experimental results and the predicted ANFIS outcomes, with an average prediction error below 8%. Specifically, the ANFIS model yielded errors of 5.1% for Ra, 13.45% for Fc, and 7.92% for TW. The model exhibited excellent agreement with experimental data, demonstrating high prediction accuracy and generalization capability. 3-D graphs are plotted for a better understanding of the effect of process parameters on Fc, Ra, and TW for different nanocomposites. The findings affirm the efficacy of compressed air cooling in improving machinability while minimizing environmental impact. Furthermore, the developed ANFIS model serves as a reliable tool for optimizing turning parameters for Al7075 composites, supporting the advancement of green manufacturing strategies. This research warrants further investigation into the application of ANFIS in machining processes, specifically exploring various metal matrix composite types and rigorously assessing the long-term effects of compressed air cooling on both environmental sustainability and tool life.
Copyright (c) 2025 Chinchanikar S., Patil S., Kulkarni P. https://creativecommons.org/licenses/by/4.0
Milling of a blank from austenitic stainless steel AISI 321, deposited using wire-arc additive manufacturing (WAAM)
Introduction. Wire arc additive manufacturing (WAAM), due to its “design as manufacturing” characteristic, is gradually becoming one of the most promising technologies. However, at present, there are no comprehensive comparative studies on the microstructure and mechanical properties of deposited samples made from austenitic stainless steel at different locations of the sample. In addition, their machinability remains insufficiently investigated. The purpose of this study is to compare the microstructure and mechanical properties of samples made of austenitic stainless steel ER321 (analogues – AISI 321, 0.08% C-18% Cr-10% Ni-Ti) obtained by the WAAM method at different locations within the sample and to assess their machinability by the magnitude of the components of the cutting force during end milling and the roughness of the machined surface. The properties and microstructure of samples obtained by wire-arc additive technology are investigated, and milling forces are investigated. The effect of the feed on the components of the cutting force and the roughness of the machined surfaces during conventional milling of ER321 steel workpieces using 12 mm diameter cemented carbide end mills with a wear-resistant AlTiN coating applied by physical vapor deposition (PVD) is determined. Research methods. The content of elements and the solidification pattern in various parts of the workpieces were determined using X-ray microanalysis. The microstructure of the samples was studied by a metallographic method. Stress-strain diagrams were obtained by tensile tests, and the microhardness of the samples was also measured. In comparison with the pattern of conventional milling of rolled workpieces, a pattern of changes in cutting forces and surface roughness was established depending on the feed rate during milling of deposited workpieces. Results and discussion. During deposition, ferrite with a vermicular morphology is primarily formed in the lower region of the sample, whereas austenite with a dendritic ferrite structure is observed in other regions. The microhardness values of the deposited and rolled samples are close, averaging around 230 HV0.1. The ultimate tensile strength of the rolled samples is 666 MPa, which is approximately 40 MPa higher than that of the deposited samples. During milling of the deposited workpieces, the lateral cutting force acting perpendicular to the feed direction is greater, and the surface quality is poorer. During milling of deposited workpieces, the lateral cutting force acting perpendicular to the feed direction is greater, and the surface quality is poorer. During milling of deposited workpieces, the feed force acting in the feed direction is greater under high feed rates.
Copyright (c) 2025 Zhang Q., Klimenov V.A., Kozlov V.N., Chinakhov D.A., Han Z., Qi M., Ding Z., Pan M. https://creativecommons.org/licenses/by/4.0
Mathematical analysis of the titanium alloy surface profile under various modes of electromechanical treatment
Introduction. Currently, many mathematical approaches exist for approximating surface profile curves. Most employ volumetric mathematical expressions to describe surface profile parameters after various types of processing. Purpose of the work is to select a mathematical apparatus that is simple enough from an engineering perspective to approximate the surface profile of VT22 titanium alloy samples after surface plastic deformation (SPD) and various electromechanical processing (EMP) modes, with the possibility of eliminating random technological errors. The paper investigates the effect of EMP modes using alternating and direct current at densities of 100, 300, and 600 A/mm2, considering both the application of force by the deforming tool-electrode (150 N) and its absence (10 N), on the surface geometry of VT22 titanium alloy samples. The electromechanical processing of metal alloys used in this work can significantly change the geometric profile, structure, and operational properties of the surface. Its distinctive feature is the creation of both microdeviations (roughness) and macrodeviations and relief (waviness, “oil pockets”, build-ups from metal surfacing to the repair size) on the surface. Research methods. Profilometric analysis was performed using a PM-7 device, followed by processing of the roughness measurement results using the fast Fourier transform (FFT) on the surface of a cylindrical sample made of VT22 titanium alloy with a diameter of 16 mm after electromechanical rolling with an tool-electrode, previously subjected to semi-finish turning. The error of the model curves of the surface profile was estimated using the Pearson correlation coefficient (R). Results and discussion. The use of high-density direct current helps to obtain a surface with a high relative support length of the profile (98.8%), a low arithmetic mean deviation of the profile (1.9 μm), and an average step of profile irregularities (56 μm). Based on the FFT, the considered modes of electromechanical processing contribute to the formation of profile waviness with different pitch and height. The greatest correlation is observed for modes 2, 4, and 9 (R > 0.7), while the lowest correlation coefficient was noted for EMP with a direct current density of 100 and 300 A/mm2 (modes 5 and 6, R < 0.25).
Copyright (c) 2025 Romanenko M.D., Zakharov I.N., Bagmutov V.P., Barinov V.V., Nguyen M.T. https://creativecommons.org/licenses/by/4.0
Evaluation of the melting ability of oxide fluxes in A-TIG welding of carbon and low-alloy steels
Introduction. Tungsten inert gas (TIG) welding has gained widespread popularity due to its advantages, including effective shielding, a stable arc, easy heat input adjustment, reduced metal spatter, and an attractive weld appearance. However, relatively shallow penetration and low efficiency limit its application. To improve welding efficiency and expand its scope of application, researchers both domestically and internationally have conducted significant studies aimed at increasing the energy density of the traditional TIG arc. This includes activating TIG (A-TIG) arc welding, which utilizes a flux applied to the weld surface. Further investigation of the mechanism for increasing arc energy density in A-TIG welding will allow us to propose new ideas and methods for highly efficient TIG welding technology. The purpose of this study is to evaluate the technological potential of using oxide activators TiO2 and SiO2 to improve penetration efficiency and weld quality of carbon and low-alloy steels. Methods. This work involved comparative A-TIG welding tests. The tests included the use of 3.5 mm and 8 mm thick plates (300 mm × 300 mm) made of unalloyed (carbon) steel St3 and low-alloy steel 0.09 C-2Mn-Si. Welding tests included the use of single-component fluxes in the form of oxides (TiO2, SiO2). All experimental welds were performed under the same conditions, without the use of filler metal (TIG welding), with a current in the range of 10–200 A and a welding speed of 150 mm/min. Arc voltage was maintained in the range of 10.4 V to 12.8 V; heat input was in the range of 0.499 kJ/mm to 0.614 kJ/mm. All welds were subjected to visual inspection of the surface condition and macrostructural studies to determine their dimensions. Results and discussion. Most tests observed significant differences in arc shape compared to traditional TIG and A-TIG processes. Results of A-TIG welding tests on unalloyed and low-alloy steels showed that penetration depth increased slightly in steels characterized by a higher degree of deoxidation and metallurgical purity. Evidently, not every activator was responsible for the increased penetration depth, but the use of TiO2 and SiO2 oxides was undoubtedly beneficial. An arc constriction mechanism is proposed, which is widely applicable to A-TIG welding of steel with various types of fluxes studied. Arc constriction occurs due to the formation of negative ions in the outer region of the arc or due to the flux coating on the surface. Thus, arc constriction increases the current density and heat intensity at the root of the anode. This increases the force and pressure of magnetic constriction, resulting in a strong downward convection flow. The use of silicon and titanium oxides (TiO2 and SiO2) increases penetration depth during A-TIG welding, regardless of steel type and grade. The degree of penetration increase was limited to a range of 40% to 200%.
Copyright (c) 2025 Karlina A.I., Kondratiev V.V., Gladkikh V.A., Vitkina G.Y., Kononenko R.V. https://creativecommons.org/licenses/by/4.0
Optimal milling parameters of 0.12 C-18 Cr-10Ni-Ti stainless steel fabricated by electron beam additive manufacturing
Introduction. Unlike traditional manufacturing processes, additive manufacturing (AM) offers improved efficiency while being environmentally friendly. A significant limitation hindering the adoption of wire-based electron beam additive manufacturing (EBAM) technology is the relatively low quality and high surface roughness of 3D-printed parts. The purpose of this study is to establish the optimal values of milling process parameters (rotational speed, feed rate, and milling width) based on the simultaneous evaluation of the surface roughness of the machined surface and the material removal rate. Methods and materials. This study investigated specimens fabricated using EBAM technology. Uniaxial tensile tests were conducted on an electromechanical testing machine. Cutting forces were determined with a Kistler 9257B dynamometer. Milling studies of EBAM 321 steel workpieces were performed on a semi-industrial CNC milling machine. Results and discussion. It was shown that in order to increase the material removal rate and reduce the cutting force on a milling machine without the use of coolant, it is recommended to increase the milling speed, but not to increase the feed rate. To investigate the relationship between material removal rate and surface roughness relative to milling parameters on a semi-industrial machine (with an average stiffness of the portal frame), multiple linear regression models and nonlinear models based on feedforward neural networks were employed. It was demonstrated that linear regression models are sufficient for predicting optimal milling parameters. However, it should be noted that the study was conducted within a narrow range of gentle machining conditions, with short processing times and without accounting for tool wear. Under these constraints, the optimal milling parameters for EBAM 321 steel were predicted as follows: spindle speed of 4,500 rpm, feed rate S = 404 mm/min, and cutting depth B = 0.43 mm, resulting in a predicted surface roughness (Ra) of 0.648 µm and a material removal rate of 695 mm³/min.
Copyright (c) 2025 Qi M., Panin S.V., Stepanov D.Y., Burkov M.V., Zhang Q. https://creativecommons.org/licenses/by/4.0
Investigation of the thermal loading during turning of a metal–composite system as a function of cutting speed, feed rate, and depth when machining a thin-walled 2 mm metal shell
Introduction. This paper is devoted to the study of the thermal loading of the turning process for metal–composite systems (MCS) consisting of a thin-walled, additively manufactured metal shell and a metal-polymer filler. The purpose of this study is to investigate the influence of technological turning parameters on the temperature in the cutting zone of metal-composite systems (MCS) with a 2 mm thick metal shell and to determine the permissible machining conditions that prevent thermal degradation of the metal-polymer filler. Methodology. For experimental modeling of the MCS, a hardware-software complex was developed, including a replaceable metal sleeve made of 0.12C18Cr-10Ni-Ti steel, ferrochrome metal–polymer (TU 2257-002-48460567-00), three thermocouples with MAX6675 analog-to-digital converters, and a wireless data transmission module based on an ESP32. The temperature at the metal-metal-polymer interface was recorded in real time. The results were verified using a non-contact method with a FLUKE Ti400 thermal imager (error of 3–5 °C). The experiment was conducted according to a full factorial design 23 + n0 with variation of cutting speed V (m/min), feed rate S (mm/rev), and depth of cut t (mm), including central points for assessing the curvature of the response surface. Results and discussion. Based on the experimental data obtained for the 2 mm shell, a second-order regression model (2T3) was constructed, demonstrating high adequacy. Analysis of the model coefficients showed that the depth of cut t has the greatest influence on the temperature increase, followed by the feed rate S, while the cutting speed V has the least effect within the studied range. Using the model, response surfaces and contour maps were constructed, allowing visualization of safe machining regions that satisfy the constraint T ≤ 170 °C — the heat resistance limit of the metal-polymer. The obtained dependencies provide a basis for standardizing finishing turning parameters for tooling components with additively formed shells and metal-polymer fillers.
Copyright (c) 2025 Lubimyi N.S., Chetverikov B.S., Klyuev S.V., Zagorodniy N.A., Polshin A.A., Maltsev A.K., Bytsenko M.V. https://creativecommons.org/licenses/by/4.0
Modern methods of manufacturing of complex-profile electrode-tools for electrical discharge machining: a literature review
Introduction. Pilot production plays an important role in modern mechanical engineering. Copy-piercing electrical discharge machining (CPEDM) technology has become widespread in machining pilot parts manufactured in flexible production flows. Manufacturing tool-electrodes (TE) is one of the main stages of the CPEDM technological cycle. Purpose of the work. Review of existing studies of modern methods of manufacturing tool-electrodes for electrical discharge machining. Research methods. A literature review of studies in the field of electrical discharge machining devoted to tool-electrodes, carried out mainly over the past 20 years, is presented. Various configurations of structural elements machined using CPEDM technology, as well as TE configurations for their machining, are described. The dependences of the influence of the geometric parameters of the simplest TE configurations on the output parameters of CPEDM are shown. The main groups of TE manufacturing methods are identified. The limitations, advantages, and disadvantages of alternative methods to traditional ones are described. The main trends in the development of modern TE manufacturing methods are revealed. Results and discussion. Based on the literature review of modern research in the field of electrical discharge machining, current trends in the development of tool-electrode configurations are presented, and problems in the manufacture of complex-shaped tool-electrodes using traditional methods are identified. It has been established that among the alternative methods for manufacturing tool-electrodes, investment casting, powder metallurgy, and additive methods are of greatest interest to modern scientists. It has been shown that each method has its own advantages and disadvantages, confirmed by a number of studies. The following current areas of development of complex-shaped tool-electrodes and methods for their manufacture are highlighted: topological optimization of tool-electrodes, use of modern high-tech casting methods; expansion of the range of tool-electrodes materials with improved electrical discharge properties; optimization of powder metallurgy modes, FDM printing, and selective laser melting; increasing the thickness and quality of tool-electrodes coatings obtained using rapid prototyping technologies.
Copyright (c) 2025 Ablyaz T.R., Osinnikov I.V., Shlykov E.S., Muratov K.R., Blokhin V.B. https://creativecommons.org/licenses/by/4.0
Investigation of the effect of process parameters on photochemical machining of SS316l for manufacturing vascular stents
Introduction. Photochemical machining (PCM) is a non-traditional machining method capable of developing burr-free and stress-free biomedical components. A stent is a small meshed tube used to remove blockages and open blood passages in arteries and veins. SS316L is one of the recommended materials for stents due to its biocompatibility and machinability with photochemical processes. Vascular stents are made from metal mesh, fabric, silicone, or combinations of materials. The purpose of this work is to investigate the effect of process parameters on the PCM process during the machining of SS316L and to manufacture an SS316L stent as a substrate using photochemical machining. The manufactured stent is used in larger arteries, such as the aorta, to provide a stable channel for blood flow. Methods of investigation. The process parameters for the photochemical machining process were optimized using the Taguchi method with an L9 experimental array (DoE). The effect of process parameters on responses was investigated using F-values. An ANN was employed as a predictive tool for observing deviations in the responses. Results and discussion. The optimum set of machining parameters was obtained and utilized for manufacturing the vascular stent. A phototool with the required stent strut size was developed using CAD software. Controlled etching with ferric chloride generated the mesh, and laser seam welding was performed to develop the tubular stent for placement in blockages. The dimensions of the developed stent were measured with SEM, and the stent strut size was found to vary from 312 µm to 900 µm.
Copyright (c) 2025 Agrawal D., Patil S., Washimkar D., Ambhore N., Agrawal D. https://creativecommons.org/licenses/by/4.0
Prediction of tool wear intensity during machining of titanium nickelide TN-1
Introduction. One of the crucial criteria for evaluating the effectiveness of the chosen strategy for machining blanks is the tool wear intensity. Reducing the intensity of tool wear leads to a reduction in production costs related to cutting tool expenditures and an improvement in overall productivity. The purpose of this work is to reduce tool wear intensity during the machining of a blank manufactured from the shape memory alloy titanium nickelide TN-1. Methods. As part of this research, a complete three-factor turning experiment was conducted on the alloy blank to determine the cutting insert wear intensity over a wide range of cutting conditions. During the tests, the geometric parameters of the resulting chips, specifically thickness and width, were measured. By constructing graphs representing the dependencies of the chip parameters, approximating these dependencies, and assessing the reliability of each approximation, a key parameter was identified for developing a methodology to predict tool wear intensity. Results and discussion. The study demonstrates that for predicting the cutting insert wear intensity when turning a titanium nickelide TN-1 blank, it is advisable to use the dependency on the resulting chip thickness. The established mathematical dependency is described by a system of equations that allows for the determination of the cutting insert wear intensity and the calculation error. The probability of accurately predicting the true value of tool wear intensity within the specified range is at least 87.5% at a 95% confidence level, which indicates sufficient practical accuracy. The essence of the methodology developed within this study for predicting the cutting insert wear magnitude lies in performing a test cut to obtain a chip whose thickness is then used to calculate the wear intensity magnitude and the most probable absolute error based on the established dependencies. Additionally, the study establishes that the wear intensity dependency exhibits a minimum point. This circumstance allowed for the establishment of the minimal possible wear intensity during TN-1 alloy machining, as well as the associated calculation error: δVmin = (0.432 ± 0.096)·10−3 mm−2. For an optimal chip thickness of a = 0.34 mm, the closest tested mode yielding a comparable wear intensity of 0.475⋅10−3 mm−2 is: cutting speed 5 m/min, feed rate 0.2 mm/rev, depth of cut 0.3 mm. The chip thickness for this mode was 0.4 mm.
Copyright (c) 2025 Kisel' A.G., Bobrovskij N.M., Podashev D.B., Tselikov P.V., Kamenov R.U. https://creativecommons.org/licenses/by/4.0
Anisotropy of properties in metal materials fabricated by wire arc additive manufacturing (WAAM)
Introduction. Additive manufacturing (AM) technologies, particularly wire arc additive manufacturing (WAAM), offer a rapid and cost-effective approach for producing complex metal components. However, WAAM can induce anisotropy in the resulting material's physical and mechanical properties. This anisotropy must be considered in design and application to ensure reliable performance in service. The purpose of the work. This study aims to quantitatively assess the anisotropy of mechanical properties in materials produced by WAAM to enhance the reliability of components used in critical applications. Research methodology. Samples were fabricated from low-carbon alloyed steel (0.08 C-2 Mn-1 Si), stainless steel (0.04 C-19 Cr-9 Ni), and aluminum alloy (97 Al-3 Mg) using the WAAM process. These samples were then subjected to mechanical testing to determine their tensile and impact toughness and hardness. Results were compared to those of the materials in the initial state to determine the relative anisotropy of each property. Results and discussion. For 0.08 C-2 Mn-1 Si steel, the tensile strength of WAAM-fabricated samples exhibited minimal variation across different orientations, indicating relatively high isotropy (relative anisotropy of 1.3 %). A relative anisotropy of 33 % was observed for elongation, 21 % for impact toughness, and 16 % for hardness. The 0.04 C-19 Cr-9 Ni stainless steel exhibited a relative anisotropy of 15.1 % for tensile strength, 244 % for elongation, 33 % for impact toughness, and 4% for hardness. The 97 Al-3 Mg aluminum alloy showed a significant relative anisotropy in tensile strength (83.6 %) and relative elongation (513 %) due to differences in the “vertical” direction. Impact toughness exhibited only slight variations (28 %) depending on sample orientation, while hardness can be considered isotropic. In general, hardness demonstrated the lowest relative anisotropy, while elongation exhibited the highest.
Copyright (c) 2025 Kirichek A.V., Soloviev D.L., Yashin A.V., Silantyev S.A., Aborkin A.V., Novikov M.A. https://creativecommons.org/licenses/by/4.0
Study of tribological properties of silicon bronze in different structural states
Introduction. Silicon bronzes are widely used in critical friction units due to their combination of corrosion resistance, machinability, electrical conductivity, and satisfactory mechanical properties. Electron beam additive manufacturing (EBAM) is promising for the production of complex parts, but it forms a large columnar grain structure, leading to anisotropy of properties and limiting their practical application. Methods of severe plastic deformation (SPD), such as multi-axis forging and rolling, are effective for refining the structure, eliminating anisotropy, and increasing strength. However, their effect on the overall properties of silicon bronzes has not been sufficiently studied. Purpose of the work. The purpose of this study is a comparative analysis of the effect of the structural state of silicon bronze on its mechanical characteristics and tribological properties under dry sliding friction. Research methods. Samples in five structural states were obtained by electron-beam additive manufacturing (1), hot rolling (2), multi-axis forging (3), rolling at room temperature (4), and low-temperature annealing after rolling (5). The structure of the samples was investigated by optical metallography and transmission electron microscopy. Mechanical tests were carried out by tensile testing of double-sided dog-bone samples and Vickers microhardness testing. Tribological tests for dry sliding friction against 52100 steel were carried out with a constant load and speed. During friction, the friction coefficient (FC), vibrations in the normal and tangential directions, and acoustic emission (AE) were recorded. A detailed analysis of the surface and subsurface layer of friction tracks was performed using confocal laser scanning microscopy, as well as scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDS). Results and discussion. The microstructure of the samples after EBAM exhibits large columnar grains, while after hot rolling it shows large equiaxed grains with twins. Multi-axial forging results in the formation of subgrains (lamellae) (<100 nm) with a high dislocation density. Rolling leads to further refinement of the original grains and the formation of elongated submicron grains. Low-temperature annealing forms more equiaxed submicron grains (100–200 nm) with a reduced dislocation density and high-angle boundaries. Samples with a coarse-grained structure have low strength and hardness. After SPD, the strength and hardness increase significantly, and the relative elongation decreases compared to the original material. Low-temperature annealing provides maximum strength with partial restoration of ductility and a decrease in hardness. The smallest and most stable friction coefficient, as well as minimum vibration amplitudes (especially in the tangential direction), were recorded for samples after SPD. The greatest wear occurred for the sample in the as-received condition (hot rolling). SPD reduces wear by 2.1–2.2 times compared to the hot-rolled and EBAM samples. Low-temperature annealing increases wear by 10% relative to the sample after rolling. The predominant wear mechanisms were determined to be: mixed (adhesive-oxidative) for bronze after EBAM; adhesive for hot rolled; and oxidative for samples after SPD. Based on metallographic studies, it was found that the depth of subsurface deformation is maximum for coarse-grained samples (145–155 μm) and decreases by 3.3–4.7 times after SPD. Conclusion. A comprehensive study has revealed a decisive influence of the structural state of 96% Cu-3% Si-1% Mn bronze on its key properties. The use of SPD methods (multi-axial forging and rolling) has proven to be highly effective in dramatically improving the mechanical and tribological properties of silicon bronze, regardless of the original production method (hot-rolled steel or electron beam additive manufacturing).
Copyright (c) 2025 Filippov A.V., Shamarin N.N., Tarasov S.Y. https://creativecommons.org/licenses/by/4.0
Effect of heat treatment on the structure and properties of magnesium alloy MA20 subjected to severe plastic deformation
Introduction. One of the most promising fields for the application of magnesium alloys is medicine. Their key advantages are bioresorbability and a low elastic modulus, comparable to that of human cortical bone (up to 30 GPa). Biocompatible Mg-Zn-Zr-Ce (MA20) system alloys are among the most promising for medical applications. Due to their relatively low mechanical properties, the development of severe plastic deformation (SPD) techniques for forming an ultrafine-grained (UFG) state in bulk billets of the Mg-Zn-Zr-Ce alloy to achieve optimal functional properties requires further research. Analyzing the conditions for forming a high-strength UFG state necessitates considering various strengthening mechanisms, including well-known ones related to the effect of UFG structures. Identifying the deformation and strain hardening mechanisms in magnesium alloys subjected to SPD is also highly relevant. The purpose of this work is to establish the mechanisms of strain hardening and to investigate the influence of heat treatment on the structure and properties of the MA20 magnesium alloy after combined SPD. Research methods. The study object was the MA20 alloy in a UFG state (wt. %: Mg – 98.0; Zn – 1.3; Ce – 0.1; Zr – 0.1; O – 0.5). The UFG state was achieved via a combined SPD process involving ABC-pressing followed by multi-pass rolling in grooved rolls. To study the effect of annealing on the microstructure and mechanical tensile properties, samples were annealed in air at temperatures of 200, 250, 300, and 500 °C for 24 hours. The microstructure and phase composition of the samples were investigated using optical and transmission electron microscopy. Results and discussion. It was established that applying a combined SPD method (ABC-pressing and multi-pass rolling) to the MA20 alloy results in the formation of an ultrafine-grained structure with an average grain size of about 1 μm. This leads to a significant increase in yield strength (σ0.2) to 250 MPa and ultimate tensile strength (σu) to 270 MPa, while simultaneously reducing ductility to 3%. Annealing at 200 °C was found to preserve the UFG state in the MA20 alloy and to lead to a 100% increase in ductility, with an 8% decrease in σ0.2 and a 4% decrease in σu compared to the initial UFG state (non-annealed). Conclusions. It was revealed that the grain boundary (σgrain = 202 MPa) and dislocation (σdis = 69 MPa) strengthening contributions provide the most significant increase in the strength of the UFG MA20 magnesium alloy. For the magnesium alloy in the UFG and fine-grained (FG) states, a critical grain size interval of (1–7) μm was identified, corresponding to a sharp increase in the intensity of change for the calculated contributions of dislocation (dσdis/ dd), grain boundary (dσgrain/ dd), overall strengthening (dσtotal/dd), and dislocation density (dρ/dd). For the coarse-grained (CG) state of the alloy in the grain size range (7–40) μm, these parameters stabilize.
Copyright (c) 2025 Luginin N.A., Eroshenko A.Y., Prosolov K.A., Khimich M.A., Glukhov I.A., Panfilov A.O., Tolmachev A.I., Uvarkin P.V., Kashin A.D., Sharkeev Y.P. https://creativecommons.org/licenses/by/4.0
Effect of laser radiation wavelength on the structure and functional properties of TiNi alloy during UV laser treatment
Introduction. The widespread use of TiNi-based functional alloys in medicine requires targeted management of their surface properties, such as wettability and biocompatibility. One of the promising methods for surface modification is laser treatment, especially in the UV range of the spectrum. The efficiency of UV laser treatment is due to the high photon energy, strong absorption by metals, and the shallow depth of the thermal effect zone. The purpose of this work is to investigate the effect of UV laser radiation wavelength (266 and 355 nm) on the structural and phase state, chemical composition, and wettability of the TiNi alloy surface, with the goal of subsequently controlling the material's functional properties. Materials and research methods. TiNi surface modification was performed using a pulsed Nd:YAG laser operating at wavelengths of 266 and 355 nm in ambient air. The modified surfaces were analyzed by scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). Microstructure, elemental composition, and phase composition were analyzed by X-ray diffraction (XRD). Wettability was estimated using the sessile drop method. The free surface energy, along with its dispersive and polar components, was then calculated from the contact angle data using the OWRK method. Results and discussion. UV laser treatment, varying parameters such as laser radiation wavelength and scanning speed, was found to induce changes in the morphology, elemental composition, phase composition of the surface layer of TiNi alloy samples, and their surface properties. Following UV laser treatment at wavelengths of 266 and 355 nm and low scanning speeds (V = 200 and 500 µm/s), single microcracks or microcrack networks resulting from thermal exposure were observed on the specimen surfaces. The oxygen content on the TiNi surface increased by a factor of 5 to 18 compared to the initial state after UV laser treatment. Furthermore, the phase composition of the TiNi alloy underwent noticeable changes, with titanium oxide phases being detected on the surface after laser exposure. The higher-energy photons (λ = 266 nm) resulted in a more pronounced change in the surface morphology and properties of TiNi compared to the 355 nm radiation under identical treating conditions. UV laser treatment significantly increased the surface hydrophilicity: the contact angle decreased from ≈75° in the initial state to ≈25° and ≈11° after treatment with 355 and 266 nm radiation wavelength, respectively. Additionally, an increase in the free surface energy of the TiNi specimens was observed, primarily due to a significant increase in the polar component.
Copyright (c) 2025 Sablina T.Y., Kandaurova M.Y., Zyatikov I.A., Panchenko Y.N. https://creativecommons.org/licenses/by/4.0
Effect of Zr, Sc, and Hf additions on the microstructure formation of cast ALTEK alloys
Introduction. Aluminum alloys of the Al-Cu-Mn system, alloyed with 23% copper and 1–2% manganese (ALTEK), are distinguished by heat resistance and high mechanical properties due to the formation of nano-dispersed particles of the Al20Cu2Mn3 phase. When exposed to high temperatures (up to 400°C), the particles block the processes of polygonization and recovery, hindering the movement of grain boundaries. A promising direction for improving these alloys is the modification of the cast structure with transition metals (TMs). An insufficient content of TMs does not provide a modifying effect, while an excessive amount leads to a reduction in strength due to the formation of a large number of coarse intermetallic particles. The subject of this work a ALTEK alloys alloyed with Mg, Zr, Sc, and Hf. The purpose of the work is to determine the optimal concentrations of scandium, hafnium, and zirconium required for effective modification of the cast structure of ALTEK alloys during complex alloying. The effect of complex additions of transition metals (Zr, Sc, Hf) on the formation of the cast structure of Base0.15Zr0.05Sc0.05Hf, Base0.1Zr0.14Sc0.16Hf, Base0.1Zr0.2Sc0.16Hf, and Base0.1Zr0.25Sc0.16Hf alloys is investigated in comparison to the base alloy. The research methods were optical and scanning electron microscopy, and X-ray diffraction analysis. Results and discussion. Modification of the grain structure in alloys with a scandium content of less than 0.20% is not observed, and the average grain structure size is 350 μm. The addition of scandium in the amount of 0.20% and 0.25% leads to a decrease in the average grain diameter to 41.8 μm and 29.7 μm, respectively. Scanning electron microscopy showed that particles of the Al6Mn and Al2CuMg phases are present in all the alloys studied. Particles of the Al3(Sc,Hf,Zr) phase are found in the Base0.1Zr0.2Sc0.16Hf and Base0.1Zr0.25Sc0.16Hf compositions. X-ray diffraction analysis revealed the Al20Cu2Mn3 phase and small amounts of Al6Mn and Al2CuMg in the base alloy and in the Base0.1Zr0.25Sc0.16Hf alloy. The structural modification is explained by the precipitation of primary Al3(Sc, Zr, Hf) particles. Application of the results. The obtained results are promising for the development of new materials for the manufacture of aerospace products. Conclusions. The addition of 0.20–0.25% scandium with a zirconium content of 0.1% and hafnium of 0.16% is the most effective.
Copyright (c) 2025 Levagina A.A., Aryshenskii E.V., Konovalov S.V., Rasposienko D.Y. https://creativecommons.org/licenses/by/4.0
Study of abrasive wear resistance of flux-cored wires during surfacing on high-manganese Hadfield steel
Introduction. Austenitic high-manganese steel is commonly used in various railway and mining components, such as crusher plates, where high impact and abrasive resistance and sliding wear resistance are required, as it exhibits a unique combination of high toughness and high work-hardening ability. Therefore, it is important to understand the behavior of wear-resistant materials such as austenitic high-manganese steel under impact and sliding wear. However, this steel has a limitation: it develops its high work-hardening ability only under high impact loads and high-stress conditions. Alternatively, various hardening methods, surfacing, or replacement with low-carbon, high-alloy steels and high-chromium cast irons are used. The purpose of this study is to evaluate the abrasive wear resistance of flux-cored wires during surfacing on high-manganese Hadfield steel. Methods and materials. This study examines surfacing wires whose main alloying elements are chromium, vanadium, and tungsten. The chemical composition of the surfaced samples was determined using a BRUKER S1 TITAN portable X-ray fluorescence analyzer for metals and alloys. A Duramin-40 AC3 hardness tester (STRUERS APS, Ballerup, Denmark) was used to measure Rockwell hardness. 1.1% C-13% Mn steel demonstrated an initial bulk hardness of HRc = 23 ± 3. Specimens for microstructural study were selected from cast and surfaced samples. The microstructures were examined by optical microscopy after etching in 2.5% nitric acid solutions, rinsing in methanol, and immersion in 15% HCl solution. Impact abrasive wear tests were conducted on a DUCOM (TR-56-M3) impact abrasive wear testing machine (made in India). Results and discussion. An analysis of a cross-section of a 1.1% C-13% Mn steel specimen after abrasive wear testing revealed crack propagation beneath the surface of the part, with no visible connection to the surface, indicating that cracks initiated both at and below the surface. The microstructure of the surfaced layers, rich in finely dispersed boron carbides dispersed in the martensitic matrix, combined with a lamellar molybdenum boride phase, suggests that the material surfaced on Hadfield steel may possess higher hardness and wear resistance than the base material. Industrial tests of surfaced beaters revealed that the dominant wear mechanisms are micro-cutting, pitting, and micro-fracture (chipping and micro-indentation). Based on the results of the studies of surfacing materials, it can be concluded that wires with chromium content in the range of 3–6% have the characteristics for applications requiring high abrasive wear resistance in the mining industry.
Copyright (c) 2025 Karlina Y.I., Konyukhov V.Y., Oparina T.A. https://creativecommons.org/licenses/by/4.0
Development of an assessment method for pickup formation on furnace rolls
Introduction. During the recrystallization annealing of cold-rolled electrical and automotive steels, the formation of pickups on the surface of furnace rolls presents a significant issue, as they lead to surface damage of the steel strip in the form of indentations. The focus of the present study is the evaluation of this defect. Methods. To this end, a laboratory-based methodology was developed to assess the tendency of furnace rolls to form pickups. The method replicates the contact interaction between the furnace roll and the steel strip under real annealing conditions, taking into account the applied contact pressure, a temperature range of 700–900 °C, the (H2–N2) furnace atmosphere, and a humidity level arising from the presence of oxygen adsorbed on the steel strip. To validate the method’;s reliability, a comparative analysis was conducted between pickups formed on the roll surface after industrial operation and those generated under laboratory conditions in the contact zone between steel samples made of roll and strip materials. The analysis employed optical microscopy, X-ray diffraction, and scanning electron microscopy. Results and discussion. The study confirmed that the developed methodology produces pickups on the specimen surfaces with morphology, chemical composition, and phase structure closely resembling those observed on the furnace rolls. A comparative assessment of the pickup formation rate between a typical furnace roll material (EI 283 steel) and a NiCrAlY coating applied by plasma spraying revealed that the pickup formation rate for the EI 283 steel was an order of magnitude higher. The validated methodology can thus be used to evaluate the effectiveness of strategies aimed at mitigating pickup formation on furnace rolls under long-term high-temperature contact conditions.
Copyright (c) 2025 Bersenev K.A., Puzanov M.P., Chernov A.A., Korobov Y.S., Karenina L.S., Khudorozhkova Y.V., Makarov A.V., Davydov D.I., Kinzhebaeva G.M. https://creativecommons.org/licenses/by/4.0
Structure and properties of coatings based on refractory elements obtained by the method of non-vacuum electron beam surfacing
Introduction. The development of modern industry requires materials capable of withstanding high temperatures and loads while maintaining functionality and performance. Traditional materials, such as 0.4 C-Cr structural steel, are widely used in mechanical engineering and are inexpensive. However, ordinary and low-alloy steels are subject to intense oxidation when exposed to temperatures above 400°C. To improve the performance of structural steels under high-temperature conditions, the development of effective methods for modifying their surfaces is an an urgent task. The purpose of this work is to develop a technology for creating high-temperature oxidation resistant surface layers on 0.4 C-Cr structural steel. For this purpose, the non-vacuum electron beam surfacing method was used, employing powder materials based on refractory elements: niobium, molybdenum, and boron. Materials and methods. In this study, modified layers were formed on 0.4 C-Cr steel using non-vacuum electron beam surfacing of Nb-Mo-B powder composites. The following research methods were used: optical microscopy, scanning electron microscopy, X-ray diffraction analysis, microhardness testing, high-temperature oxidation testing, and oxidation reaction kinetics determination. Results and discussion. The modified layers, which were 2.0–2.3 mm thick, exhibited a gradient structure consisting of molybdenum-doped niobium carbide present as dendrites and irregularly shaped crystals, as well as eutectic colonies based on the same carbide and α-Fe and α-(Mo,Fe) solid solutions. X-ray phase analysis identified the following phases in the modified layers: (Nb,Mo)C carbide and α-Fe and α-(Mo,Fe)-based solid solutions. The surfacing with Nb, Mo, and B resulted in the formation of layers on the surface of 0.4 C-Cr carbon steel that are 2.9 times harder and 3.9 times more temperature oxidation resistant than those of the unmodified steel.
Copyright (c) 2025 Bushueva E.G., Nastavshev A.E., Skorokhod K.A., Domarov E.V., Mishin I.P. https://creativecommons.org/licenses/by/4.0