In the present work, we study the possibility of application of a special calibration of the working rolls containing calibration sections of limited length, in the process of radial shear rolling of alloys of the Co-Cr-Mo system and its influence on the parameters of the process and formation of the microstructure. The results of computer simulations demonstrate that the proposed calibration enables one to decrease the radial force applied to the roll by 12–25

The article presents a novel technique for performing high reduction radial shear rolling (HRRSR) of aluminum alloy bars. For this purpose, rolls with a special calibration were developed, including a high reduction section and a roll feed angle of 20°. The proposed process was investigated using FEM simulation, first. The temperature, stress-strain state, and force parameters analysis showed that the proposed method can produce defect-free bars with a natural gradient microstructure. Afterward, the experimental alloy Al-3Ca-2La-1Mn (wt

Radial-shear rolling technology (RSR) is a modern, effective technique for obtaining structured semi-finished and final bar products from various metals and alloys, including hard-to-deform ones. Due to design features (feed angle 18-20 degrees, rolling angle 0-12 degrees, taper angle of roll 10 +/- 2,5 degrees) implemented in the RSR equipment (mini-mills) and unique trajectory-deformation conditions, the possibility of obtaining ultrafine-grained functional-gradient structure is realized. At the same time, mini-mills are characterized by compactness and versatility of working tools, which allows to reduce labor costs and follow the concept of lean production. This article reviews the industrial application of technology and equipment of RSR and scientific and applied research in this direction by various scientific groups, outlines the elements of theory, as well as the main stages of development and implementation. The reviewed publications indicate the demand for and prospects of application of RSR technology for obtaining products with a unique combination of properties.

In this paper, tensile and hardness tests of nanonickel matrix composites were conducted after rolling. We found that the fracture strength of the foil increased significantly after rolling, while the hardness of the foil decreased and then increased with the increase of rolling passes. The hardness of the rolled composites was less than that of the unrolled composites, which is a special phenomenon, and the foils obtained by cross-rolling had slightly higher hardness values than those obtained by unidirectional rolling. Variations in matrix grain size and the high density of nanoscale twins were the underlying causes of the variation in material hardness, and the presence of multiple twins within the material was responsible for the higher hardness of the cross-rolled foils.

В работе исследована возможность применения специальной калибровки рабочих валков, имеющих калибрующий участок ограниченной длины, при многопроходной радиально-сдвиговой прокатке сплава системы Co–Cr–Mo и проведена оценка ее влияния на параметры процесса и формирование микроструктуры. Результаты компьютерного моделирования показали, что предложенная калибровка позволяет сократить радиальное усилие на валок на 12–25% и перепад температур в очаге деформации между центром и поверхностью на 5–7%. При этом отмечается снижение цикличности процесса на 20% и повышение уровня максимальных сжимающих напряжений на 10–15% в сравнении с традиционной конфигурацией валков. При экспериментальном опробовании предложенной калибровки отмечено стабильное протекание процесса прокатки, полученный пруток не имел внешних и внутренних дефектов. Анализ микроструктуры показал некоторое различие в среднем размере зерна на переднем и заднем концах прутка, а также в центральной и приповерхностных его областях вследствие различных температурно-деформационных условий прокатки. Экспериментальные данные подтвердили возможность радиально-сдвиговой прокатки высокопрочного сплава системы Co–Cr–Mo с коэффициентом вытяжки до двух даже при существенном снижении температуры поверхности прутка. This study investigates the potential application of a specialized calibration of work rolls, which has a limited-length calibration section, during the radial-rolling rolling of Co–Cr–Mo system alloys and its impact on process parameters and microstructure formation. The results of computer simulation showed that the proposed calibration allows to reduce the radial force on the roll by 12–25% and the temperature difference in the deformation zone between the center and the surface by 5–7%. At the same time, the process cyclicity is reduced by 20% and the level of maximum compressive stresses is increased by 10–15% in comparison with the rolls’ traditional configuration. The experimental testing of the proposed calibration showed stable rolling process, the obtained bar had no external and internal defects. Microstructure analysis showed some difference in the average grain size at the front and rear ends of the bar, as well as in it’s central and near-surface areas due to different temperature and deformation conditions of rolling. The obtained experimental data confirmed the possibility of radial-shear rolling of high-strength alloy of Co–Cr–Mo system with elongation ratio up to 2 even at significant reduction of bar surface temperature.

This study investigates the superplastic deformation of a cold-rolled Ni/Graphene Oxide composite foil, with a particular emphasis on the mechanism that enhances the two-dimensional ultra-thin phase graphene oxide (GO). The findings reveal that intergranular fracture takes place due to a larger plastic strain in the radial direction than in the tangential direction. Furthermore, the reinforcing phase GO tends to become fibrous after rolling, with the fiber direction oriented along the radial direction. The size of matrix grains surrounded by GO does not significantly increase at high temperatures. However, during stretching, the formed voids expand along the matrix and both ends of the GO. The formation and aggregation of voids increases the likelihood of high-temperature tensile fracture of the foil, ultimately resulting in a lower elongation of Ni/GO after rolling when compared to the original foil. The two-dimensional flexible reinforcement phase tends to transform from sheet-like to fibrous. When an external force is applied, it causes the multi-layer stacked GO to appear tense, which is visually observed for the first time.

The deformation behavior and microstructural evolution of a Co–28Cr–6Mo alloy during uniaxial compression tests have been analyzed. The tests are carried out at 1000, 1100, and 1200°C and strain rates of 1, 10, and 50 s–1 using a Gleeble 3800 machine. Deformation resistance curves are obtained and the peak stresses are determined. The deformation behavior of the alloy is characterized by an increase in the flow stress with the strain rate and by its decrease with increasing temperature. The peak stress is recorded at higher strains when the temperature decreases or the strain rate increases. Deformation in the temperature range of 1000–1100°C is accompanied by strain hardening and partial dynamic recrystallization. After deformation at 1200°C, the microstructure of specimens consists of equiaxed recrystallized grains, and the microhardness does not depend on the strain rate. At the same time, an increase in the strain rate at 1000–1100°C leads to a slight decrease in the microhardness. The data obtained can be used for selecting deformation conditions for the Co–28Cr–6Mo alloy using industrial metal forming methods.

This paper describes the analysis of temperature field of workpiece during radial shear rolling (RSR) of biomedical Co-28Cr-6Mo alloy. In the process of hot metal forming, the temperature distribution in the deformation zone has a significant influence on the quality and properties of the final product. In some cases, the deformation within a narrow temperature range is required to provide the desired properties. To obtain data on change in temperature, the computer simulation of RSR was carried out using finite element method. According to simulation results, the temperature distribution of bar depending on the variable process parameters such as temperature of workpiece, rotary velocity of rolls, elongation ratio, diameter of workpiece, and temperature of tool was evaluated. It was determined that the most significant parameters influencing on the distribution of the temperature field are the workpiece heating temperature and the rolling speed. The RSR process makes it possible to effectively manage the distribution of temperature field due to selecting technological parameters and, thereby, control the formation of the alloy structure. The data obtained can be useful for developing the modes of RSR of Co–Cr–Mo alloy.

Effect of radial shear rolling on the morphology of intermetallic particles, and the mechanical properties of 7075 alloy at different processing temperatures and heat treatment after deformation was investigated. The results were consistent with data on metallographic investigation of phase particle shape, counts, and distribution. It was found that the formation, quantitative distribution, and circularity of particles at the surface and in the centre of the bar depended on the processing temperature and temperature gradient between surface and centre and were defined with a scheme of stresses in the deformation zone. The values of strength properties for all bars obtained by RSR depended on the processing regimes, while plasticity (elongation to failure δ = 14%–20%) increased with the growth of processing temperature. Article highlights Radial shear rolling makes it possible to obtain aluminium alloy bars with a gradient structure and a combination of high strength and ductility. The influence of the RSR method is reflected in the nature of the distribution of dispersive particles in the matrix of alloy. Mechanical properties of bars subjected to the RSR method depend on the initial processing regimes, while the level of plasticity increases with the growth of processing temperature.

A method of obtaining bars from the Al–Mg–Sc alloy by radial-shear rolling (RSR) and its effect on the microstructure and mechanical properties were discussed. After RSR at different temperatures (400, 300, 250 °C), a gradient microstructure forms over the cross-section of the bars. From the surface to the half of radius, initial microstructure transform to an ultrafine-grained dynamically recrystallized structure with equiaxed grains (0.5 to 2 µm) and a well-developed high angle grain boundaries net. Near the center of the bars, a deformed fiber structure of grains with well-developed low angle grain boundaries and an average subgrain size of 5 µm was obtained. The alloy structure has a deep hierarchical arrangement characterized by the existence of submicron size particles and 10–20 nm sized Al3(Zr,Sc) nanoparticles. The mechanical properties (ultimate tensile strength 436 MPa, yield strength 350 MPa) are superior to those of almost all studied deformation methods for this alloy.

Проведен анализ деформационного поведения и эволюции микроструктуры сплава Co-28Cr-6Mo в процессе испытаний на одноосное сжатие. Испытания проводились при температурах 1000, 1100 и 1200 °C и скоростях деформации 1, 10 и 50 с -1 на установке Gleeble 3800. Получены кривые сопротивления деформации и определены значения пиковых напряжений. Деформационное поведение сплава характеризуется возрастанием напряжения течения с увеличением скорости деформации и его снижением при повышении температуры. Пиковое напряжение зафиксировано при более высоких степенях деформации при понижении температуры и увеличении скорости деформации. Деформация в диапазоне температур 1000-1100 °C сопровождается процессами деформационного упрочнения и частичной динамической рекристаллизации. После деформации при 1200 °C микроструктура образцов представляет собой равноосные рекристаллизованные зерна, а микротвердость не зависит от скорости деформации. В то же время повышение скорости деформации при температурах 1000-1100 °C приводит к незначительному снижению микротвердости. Полученные данные могут быть использованы при выборе режимов деформации сплава Co-28Cr-6Mo с использованием промышленных способов обработки давлением.

The article discusses the main structural features of radial-shear rolling mini-mills and their most common sizes. A generalized algorithm for designing such mills using modern CAD systems is described. The main approaches to the methodology of software adaptive design of models in engineering are listed with their features and differences. In particular, the methodology of horizontal modeling, explicit modeling methodology, and resilient modeling strategy are considered. The article describes the method of virtual squeezes and presents the main geometric scheme of the spatial position of the rollers of the longitudinal profile. The data obtained as a result of the calculations were encoded and summarized in tables. The formulas presented were used in the parametric design of the roller unit of the three-roller mill 30-70 using Autodesk Inventor software. The obtained parametric model, using classical formulas of the virtual squeezes method, allows for automatic reconstruction of the deformation zone for new initial parameters. The developed model is applicable for three-roller mills with working roll angles δ = 5 – 15° and feed angles β = 18 – 22°. The article presents sketches and diagrams of the constructed model for different rolling angles – 5, 10, and 15°. As the rolling angle increases, a noticeable increase in the conicity of the roller is observed. The vector of future research on improving the obtained software model was indicated. Further research on improving the parametric model will include expanding the set of existing parameters to include the frame and full set of roller connections – neck, cover, pressing device, etc.

The study of microstructure and mechanical properties formation of A2024 alloy obtained by the multipass radial-shear rolling (RSR) method is discussed in this article. FEM simulation was carried out that made it possible to evaluate the influence degree of rolling temperature–velocity parameters on the strain state of material. It has been found the increase in rotary velocity of rolls significantly influences on the deformation heating of bar after RSR (predominantly in its surface layer). The combination of rolling temperature–velocity conditions at selection of deformation regime has complex effect on structure and properties formation. The analysis of sizes and distribution of phase particles has shown that the rolling at lower temperatures allowed to increase the mechanical strength due to the more intensive refinement of undissolved Fe-containing phase. The gradual decrease in the rolling temperature in each pass makes possible to achieve the high strength (UTS ~ 430 MPa and YS ~ 255 MPa) while maintaining the ductility level ~ 15%, that are comparable to ones obtained at some severe plastic deformation (SPD) methods.

Ti-Zr-Nb shape memory alloys exhibit a unique combination of properties that make them suitable for bone implants: low Young's modulus, superelastic behavior, superior corrosion resistance, and non-toxicity of all the constitutive elements.In this study, superelastic Ti-19Zr-14Nb (at.%) alloy was subjected to a combination of radial shear rolling at 900°C and rotary forging in a temperature range from 500 to 700°C to form long-length bar stocks for bone implants fabrication.Features of the grain structure, phase composition, mechanical and functional properties of the long-length bar stocks were analyzed using light microscopy, X-ray analysis, as well as during mechanical and functional tests.It was shown that after radial shear rolling at 900°C, a heterogeneous grain structure was formed over the cross-section of the bar stock, and this structure was inherited after the subsequent rotary forging at 500°C.With an increase in the forging temperature, the structural heterogeneity is eliminated and the grain size increases, while the hardness and strength characteristics of the material decrease.After rotary forging at 700°C, the alloy manifests the best combination of structural, mechanical, and functional characteristics.In this state, the long-length bar stock demonstrates a homogeneous grain structure with a certain fraction of a dynamically polygonized substructure of β-phase, a satisfactory strength (UTS ≈ 580 MPa), a low Young's modulus (E ≈ 35 GPa), the high difference between dislocation and phase yield strength (Δσ ≈ 280 MPa), and a relatively large amount of superelastic recovery strain (ε r SE max ≈ 3.1%).

The Co–28Cr–6Mo medical alloy after homogenization is tested in uniaxial compression at temperatures of 1000, 1100, and 1200°C and strain rates of 1, 10, and 50 s–1 using the Gleeble System 3800. The stress-strain curves describing the deformation behavior of the alloy are obtained. Using three models (power-law, exponential, and hyperbolic sine function) describing the flow stress, hot deformation parameters are calculated (activation energy and Zener–Hollomon parameter). The results of calculations based on the power-law and hyperbolic sine functions show the highest degree of convergence. These models can be used to accurately calculate the flow stress for given parameters of temperature and strain rate or to simulate the deformation process. Also, based on processing maps, the strain-rate modes of hot deformation of the Co–28Cr–6Mo alloy are developed, which will make it possible to select the optimal rolling modes in the future. According to the data obtained, as strain accumulates, the favorable temperature-rate conditions for hot deformation shift to the region of high temperatures and low strain rates. In this case, the extremely unfavorable zone with negative values of the plastic flow stability criterion ξ, which appears at values of the deformation parameter e = 0.3–0.4, continues to grow quite significantly with increasing strain. Hot deformation of the Co–28Cr–6Mo alloy at low compression ratios (e < 0.2) is more appropriate at temperatures above 1150°C and strain rates of at least 20 s–1. As the degree of deformation increases, lower strain rates (1–5 s–1) and higher deformation temperature should be used.

Radial-shear rolling of VT-6 alloy billets with flat and profiled ends is performed on 14–40 and 10–30 minimills. The experimental rolls are simulated using the DEFORM finite element analysis computing environment. When moving from the end of a billet along its axis, the difference in the values of hardness (HV) and deformation intensity is shown to be significantly smaller in a billet with profiled ends than in a billet with flat ends.

The article describes the development and pilot-scale testing of the technology for producing bars of the D16(T) aluminum alloy by radial-shear rolling from continuously cast billets with a diameter of 72 mm in several passes. The actual dimensions of rolled bars were within the ±0.16 mm tolerance for all bar diameters, which significantly surpasses the GOST 21488-97 requirements. According to the results of tensile tests, the values of ultimate strength, conventional yield strength, relative elongation and relative reduction were determined. Ultimate strength and relative elongation requirements specified by regulatory documents for the D16(T) alloy were met with a total elongation ratio of more than 4.2. In terms of plastic properties, the obtained bars surpass the GOST requirements by 2.1–2.5 times in the entire range of elongation ratios investigated starting from 2.07. At the same time, there is an increase in the relative elongation by 5.7–6.8 times in comparison with the initial cast state. The microstructure and morphology analysis conducted for secondary phases showed that with a decrease in the bar diameter (with an increase in the total elongation ratio), the average particle size of the α(AlFeMnSi) phase insoluble in the aluminum matrix decreases, which is a consequence of deformation processes developed during rolling. Additional grinding of inclusions during deformation processing can significantly reduce the possible negative effect of the insoluble phase on the mechanical properties of resulting bars, in particular on the plasticity properties. The microstructure analysis showed that bars after rolling and heat treatment are free from cracks, looseness, delamination, and other defects and meet the requirements of GOST 21488-97.

The article discusses the features of radial shear rolling (RSR) of the aluminum alloy Al–Mg–Sc. The modeling of the RSR process by the finite element method in the QForm 3D program with variation of the elongation ratio per pass and the rolling speed has been implemented. On the basis of the results obtained, a study of the temperature field of the rod in the deformation zone has been carried out taking into account the cyclic deformation and the configuration of the flow trajectories. It is found that changes in the temperature field of the rod in the deformation zone are determined by the difference in the trajectory flow of the metal in the surface layers and in the axial zone. When the elongation ratio is varied from 1.6 to 2.4, heating occurs inconsistently from the center to the surface. The largest increase occurs for an area that is approximately 0.3 R from the surface. For the axial zone, the temperature change in the deformation zone occurs smoothly and with an insignificant temperature difference of 5–10°C. The temperature on the surface of the rod has the greatest temperature fluctuations, which are explained by deformation heating and simultaneous contact with a cold roll during each deformation cycle. With a decrease in the rolling speed, a picture of the distribution of the temperature field of the rod in the deformation zone is observed, when the temperature of the central layers exceeds the surface temperature. Because of the long contact time of the rod with the roll, the surface temperature fluctuates up to 40–50°C with each deformation cycle. With an increase in the rolling speed, the amplitude of temperature fluctuations on the surface decreases, and the deformation heating increases. The obtained data on the relationship of controlled technological parameters with a change in the temperature field of the rod can be useful in the design of technological modes of rolling.