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In recent years, severe plastic deformation has been one of the most popular methods of increasing the mechanical properties of bars. Obtaining an ultra or nanostructure in such bars provides high strength properties, but also reduces plasticity. This paper shows that gradient structure formation in carbon steel bars gives a simultaneous increase in strength properties and some decrease in plastic properties. A new combined technology is proposed for obtaining gradient microstructure. This technology consists of drawing medium carbon steel bars on a radial-shear broaching mill and subsequent drawing. Bars with 30 mm diameter were strained at room temperature to a diameter of 16 mm in 3 passes. As a result, during three straining cycles, the average value of microhardness in the central zone was 2085 MPa, in the neutral zone was 2505 MPa, and in the surface zone was 2915 MPa. This variation of microhardness confirms gradient microstructure availability. Also there was an increase in strength characteristics almost 2 times, plastic characteristics undergo reduction due to gradient microstructure obtained during straining, but remain at a fairly good level for steel AISI 1045. The validity of the results is confirmed by a large number of experiments using a set of standard and modern research methods, such as optical, scanning and transmission microscopy, EBSD analysis, microhardness changes, fractographic method and tensile tests of mechanical properties, as well as by the results reproduction in the joint use of methods.

The changes in the properties of copper and its alloys as a result of severe plastic deformation (SPD) are reviewed. The literature review shows that contemporary materials science is aimed at solving the problem of producing ultrafine-grained materials with high-angle grain boundaries. With using of the methods of severe plastic deformation, it is possible to obtain so-called bulk nanostructured materials with grain sizes of 0.1–0.2 microns and specific substructures containing the lattice and grain-boundary dislocations. Such structures are characterised by large elastic distortions of the crystal lattice. It is believed that such fine-grained structures should simultaneously provide a high level of plastic and strength characteristics due to special stressed high-angle grains. The article discusses SPD methods such as torsion with shear, equal-channel angular pressing, screw extrusion, all-round forging, rolling with shear, etc. Among the most significant results of SPD, it is worth highlighting the increase in strength, fatigue resistance and elastic properties of the material. These changes make copper and its alloys subjected to SPD very attractive for use in many industries, including electrical engineering, aviation, medicine, etc.

The methods for fabrication of the functionally-gradient materials, which have a high complex of unique mechanical, technological and special properties, when they working on impact, wear, fatigue, experiencing increased cyclic and alternating loads, are reviewed. Considered materials are used in aerospace engineering, energy, and other industries characterized by extremely unfavourable, extreme operating conditions of critical parts, structural elements, and assemblies. Different methods for fabrication of the gradient structures are considered, in particular, the method of severe plastic deformation of metals and the process of active bending of copper. The effect of grain size, texture, and grain-growth gradients on the deformation mechanisms and mechanical properties of gradient- nanostructured nickel, as well as functionally-gradient ceramic materials are studied. The review may be of interest to researchers and scientists in the field of materials science, metallurgy, and nanotechnology.

The publications in the field of cryogenic-technologies’ applications in the processes of the thermal and deformation treatments of metals are reviewed. The most effective fields of the applications of cryogenic liquids and gases for the heat treatment of working tools and metals (titanium, aluminium, and copper alloys) are in the rolling production and heavy engineering in order to improve the product quality, equipment and tool durability, to reduce the impact on the environment and operating personnel. The effects of cryogenic treatment and cooling on the tool life, wear, cutting temperature, surface roughness, dimensional accuracy, and cutting force are considered. As a result, the use of cryogenic processing and cryogenic cooling in machining processes increases the tool life and improves surface roughness as well as reduces the temperature of the machined surface, energy consumption during operation, and, thus, reduces tool wear that contributes to an increase in productivity. The possibility of obtaining and changing the nanostructure of a metal through the cryogenic cooling is also considered. The topic may be of interest for researchers and scientists in the field of metallurgy, materials science, and nanotechnologies.

In this work, finite element simulation of the rolling-pressing process with horizontal and vertical rolls was carried out. To analyze the efficiency of metal processing, the main parameters of the stress-strain state were considered: equivalent strain, equivalent stress, average hydrostatic pressure, deformation force. Aluminum alloy Al6063 was chosen as the workpiece material. For variational simulation, models with a change in the heating temperature of the workpiece and the rolls rotation speed were constructed. The most optimal option is a model in which the workpiece was heated to 100 °C and deformation was carried out at a circumferential speed of the first pair of rolls of 60 rpm. Variants with a single temperature reduction to 20 °C, or rotation speed reduction to 35 rpm also give acceptable results to all the indicators considered. However, rotation speed reduction to 10 rpm makes it impossible to carry out a stable process at any temperature.

Traditionally, structural wire is characterized by a homogeneous microstructure, where the average grain size in different parts of the wire is uniform. According to the classical Hall–Petch relationship, a homogeneous polycrystalline metal can be strengthened by decreasing the average grain size since an increase in the volume fraction of grain boundaries will further impede the motion of dislocations. However, a decrease in the grain size inevitably leads to a decrease in the ductility and deformability of the material due to limited dislocation mobility. Putting a gradient microstructure into the wire has promising potential for overcoming the compromise between strength and ductility. This is proposed a new combined technology in this paper in order to obtain a gradient microstructure. This technology consists of deforming the wire in a rotating equal-channel step die and subsequent traditional drawing. Deformation of copper wire with a diameter of 6.5 mm to a diameter of 5.0 mm was carried out in three passes at room temperature. As a result of such processing, a gradient microstructure with a surface nanostructured layer (grain size ~400 nm) with a gradual increase in grain size towards the center of the wire was obtained. As a result, the microhardness in the surface zone was 1150 MPa, 770 Mpa in the neutral zone, and 685 MPa in the central zone of the wire. Such a symmetrical spread of microhardness, observed over the entire cross-section of the rod, is a direct confirmation of the presence of a gradient microstructure in deformed materials. The strength characteristics of the wire were doubled: the tensile strength increased from 335 MPa to 675 MPa, and the yield strength from 230 MPa to 445 MPa. At the same time, the relative elongation decreased from 20% to 16%, and the relative contraction from 28% to 23%. Despite the fact that the ductility of copper is decreased after cyclic deformation, its values remain at a fairly high level. The validity of all results is confirmed by numerous experiments using a complex of traditional and modern research methods, which include optical, scanning, and transmission microscopy; determination of mechanical properties under tension; and measurement of hardness and electrical resistance. These methods allow reliable interpretation of the fine microstructure of the wire and provide information on its strength, plastic, and electrical properties.

The article analyses the current trends in the development of additive manufacturing (AM) technologies. In recent years, the development of additive technologies is one of the industry priorities. Additive technologies, first of all, make it possible to implement effectively any design and engineering ideas in high-tech industries, such as aircraft construction, engine and engine building, rocket engineering, modern electronic devices, etc. The expansion of the range of materials for additive technologies will facilitate their introduction into mass production. Meanwhile, the development of breakthrough scientific and technical solutions in the field of AT is impossible without new powder materials. Currently, there is an evident fundamental problem, namely, the lack of comprehensive scientific research aimed at developing new powder materials for additive technologies, adapting these materials to the requirements of modern additive manufacturing machines and studying the properties of products obtained by additive technology with various variations of technical parameters.

This article presents the results of research on a new combined process involving multi-cycle wire-drawing and subsequent cryogenic cooling after each deformation stage. For theoretical research, modeling in the Deform software was performed. The analysis of temperature fields and the martensitic component in all models showed that for both considered thicknesses, the most effective option is a low deformation velocity and the conduct of a process without heating. The least effective option is to use an increased thickness of the workpiece at an increased deformation velocity and the conduct of a process without of heating to ambient temperature, which acts as a local cooling of the axial zone of the workpiece with an increase in the workpiece thickness. An analysis of laboratory studies on this combined process revealed that in the absence of intermediate heating of a wire between deformation cycles, 100% martensite is formed in the structure. However, if intermediate heating to 20 °C between deformation cycles is carried out, a gradient distribution of martensite can be obtained. And, since the wire has a circular cross-section, in all cases, martensite is distributed symmetrically about the center of the workpiece.

In recent years, severe plastic deformation has attracted the most attention as a way to improve the mechanical properties of steel bars. Obtaining ultrafine grains and nanostructures in such bars leads to a strong increase in strength properties but strongly reduces their plastic properties. This study shows that the formation of a gradient microstructure allows simultaneous improvement in the strength and plastic properties of carbon steel bars, taking into account the symmetry of the microstructure distribution from the center of machining. A new combined technology is proposed to obtain such a microstructure. This technology consists of drawing bars from medium carbon steel on a radial-displacement rolling mill and carrying out subsequent drawing. Steel bars with a diameter of 30 mm were strained in three passes to a diameter of 16 mm at room temperature. The results show that the average value of microhardness in the center, neutral, and surface areas for the three straining cycles were 1890 MPa, 2335 MPa, and 2920 MPa, respectively. This symmetrical distribution of microhardness confirms the gradient microstructure. Strength characteristics also increased almost twofold: the yield strength increased from 330 to 735 MPa, and the ultimate strength increased from 600 MPa to 1025 MPa. Relative elongation decreased from 18 to 14 MPa, and relative reduction decreased from 40 to 31%, but remained at a fairly good level for AISI 1045 steel. The validity of all results was confirmed through numerous experiments using a set of traditional and modern research methods, which included optical, scanning, and transmission microscopy. EBSD analysis allowed precise positioning of the field of vision for studying microstructural changes across the entire bar cross-section. All of these methods used together, including tensile testing of the mechanical properties and the fractographic method, allow us to assess changes in microhardness and the reproduction of results.

The paper studies the evolution of microstructure and mechanical properties of copper wire during a new combined straining process. The main point of the technological process is to strain the wire in a rotating equal-channel step die and subsequent drawing. The die rotates around the wire axis and thereby creates tension due to equal-channel angular pulling and twisting in the die. Transmission electron microscopy and EBSD analysis, as well as tensile testing and microhardness determination investigated the strained copper wire. Ultra-fine grain gradient microstructure with a high component of high-angle grain boundaries was obtained as a result of straining. The tensile strength of the strained copper wire compared to the unstrained one increases more than twice from 302 to 635 MPa, and the yield strength increases from 196 to 406 MPa. The use of such hardened copper wire in construction will reduce the weight of the structure due to the reduction of diameter.

A traditional use of high cumulative reduction ratios is not effective for manufacturing wire with high performance and mechanical properties, since cold plastic deformation reduces the wire diameter, while hot deformation has its own limitations. Thus, thermomechanical treatment of rolled steel has a huge potential to reduce costs and improve product quality when used in the construction industry. Such processing allows metalworking industries to increase the economic effect due to a more complete satisfaction of the requirements for the mechanical properties of finished rolled products. The article developed a new technology for thermomechanical processing of stainless steel wire, consisting of preliminary heat treatment to obtain an austenitic structure and traditional drawing followed by cryogenic cooling. As a result of such treatment, an ultrafine-grained structure was obtained, consisting of a mixture of austenite and α-martensite, with high strength and plastic properties. To analyze the features of the obtained microstructures, modern methods of metallographic analysis were used, such as scanning electron microscopy, transmission electron microscopy, and analysis of backscattered electron diffraction patterns. The microstructure is obtained after deformation at both temperatures and consists of a mixture of α-martensite and austenite. A structure with an average grain size of 0.5 µm was obtained by drawing using cryogenic cooling, and a microstructure of 1 µm was obtained at room temperature. The results obtained allow us to expect an increase in the performance and durability of stainless steel wire, which can be used for various purposes.

This study describes the evolution of the microstructure and mechanical properties of bimetallic aluminum-copper rods during straining by Equal channel angular pressing-drawing (ECAP-drawing). The study was conducted by means of a transmission electron microscope, EBSD analysis, tensile tests and determination of microhardness. The paper shows that an ultrafine-grained copper-aluminum composite with a gradient structure is formed during straining by ECAP-drawing. Microhardness of copper shell during 4 cycles of straining by ECAP-drawing increased from 57 to 165, and hardness of aluminum rod increased from 25 to 75 HV. This is associated with grain refinement and hardening of their boundaries by increasing the density of dislocations. Tensile test diagrams analysis has shown that straining leads to an increase in strength properties of bimetallic wire by 2 times, and as a result the plastic properties are also reduced by almost 2 times, but remain at a level applicable for further use. Application of such bimetallic rods in construction will allow reducing specific quantity of metal per structures without reduction of strength properties.

The development of ferrous metallurgy is mainly due to the requirements of the leading metal-consuming industries to improve the performance properties of structural steels to increase the permissible loads, to reduce metal consumption and improve the reliability of machines, structures, main gas pipelines, etc. With significant volumes of rolled metal production, reducing energy consumption and consuming raw materials during its production also come to the fore. In this regard, important and relevant works are the works aimed at creating the fundamentals of metals science and the development of new technologies that allow manufacturing the products with the required combination of properties directly in the rolling mill stream (excluding subsequent heat treatment) by purposefully controlling the processes of structure formation, as well as expanding the areas of the practical application of such technological schemes (in terms of brand and size assortment, rental destination, etc.). Such an approach makes it possible to increase the competitiveness of metal products determined by the achieved combination of metal characteristics, while reducing the cost of its production.