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The article describes the technology and equipment used at the enterprises of the Russian Federation in 70-90 years in the XX century for the production of bimetallic rods, the basis of the new technology is described, and the designs of mills with multi-roller calibers are presented. New mill designs, patented in the U.S., Japan, Europe and other countries, have a fairly simple design, with the use of multi-roller mills it is possible to use drives from conventional two-roller mills, the presence of radial and axial adjustment of the rolls extends the technological capabilities of the mill, the calibers of different sizes can be obtained on a single set of rolls. On such mills it is possible to obtain sections from low plastic, difficult to deform materials, as well as bimetallic compositions. These products are in high demand in aviation, space, engineering and many other industries, which are strategic directions of the state development.

We propose a technology of hardening of the working surfaces of the rollers of dies intended for the treatment of titanium alloys. The detonation deposition of the WC–10Co–4Cr alloy with a thickness of 600 μm and subsequent fusion of this layer with the help of a laser make it possible to increase the hardness of the working layer up to 1057 HV (> 67 HRC). In this case, the wear resistance becomes more than seven times higher as compared with the case of traditional thermal treatment applied for Kh12MFsteel.

Cold spray is the solid-state process for elaboration of metal coatings and free-standing parts. The absence of material melting during build-up of deposit allows to apply this technology for producing metal composites with innovative properties. The cold spray metal composites could be produced by deposition of composite powders or by simultaneous spraying of powder mixtures. The second approach is considered as the most robust and the simplest one that is important for industrial application. In the present paper, the comprehensive review of the actual knowledge about the formation of metal composite by simultaneous cold spraying of several powders is performed. The main advantages of this approach as well as the issues and the limits are analyzed. The eventual applications of the cold spray composite deposits are also discussed.

This article discusses advanced developments in the field of manufacture of electrical machine brushes. A new method for manufacturing by mixing coke pitch and graphitoplast compositions for making brushes, a new mixer design, and a new graphitoplast composition are presented.

The known designs of the contact heads of the current collectors of trolleybuses with graphite-plastic inserts are analyzed. Designs of new contact heads developed at South Ural State University are presented. Keywords trolleybus, current collector, contact head, carbon composition, insert, electrical resistance, density

One of the methods of local improvement of the wear resistance of aluminum alloy parts is the deposition of hard tungsten carbide-based coatings on the surfaces subjected to intense external influence. This paper is devoted to the characterization of the WC–10Co–4Cr (wt.%) coating deposited on an Al–4Cu–1Mg (wt.%) alloy by the detonation spray method. In comparison with the common thermal spray techniques like High Velocity Oxygen Fuel (HVOF) or Atmospheric Plasma Spraying (APS), the heat input delivered to the substrate during detonation spray is significantly lower, that is especially important in case of coating deposition on aluminum alloys. The paper presents the results of morphology investigation, microstructure, phase composition, microhardness, and cohesive strength of deposited carbide-based detonation spray coating. Results showed that the coating has a porosity less than 0.5% and the carbide grain refinement down to the submicron size during coating deposition was detected. According to the investigation, the variation of spraying distance from 270 to 230 mm does not influence on the coating microstructure and composition.

The paper is devoted to the design of new devices for the production of long-length bars of consumable electrodes for vacuum-arc melting.

Самодурова Марина Николаевна, канд. техн. наук, доцент, доцент кафедры процессов и машин обработки металлов давлением, Южно-Уральский государственный университет, г. Челябинск; mar-samodur@yandex.ru, samodurovamn@susu.ru. Огарков Николай Николаевич, д-р техн. наук, профессор, заведующий кафедрой технологии машиностроения, Магнитогорский государственный технический университет им. Г.И. Носова, г. Магнитогорск; ogarkovnikolai@mail.ru. Платов Сергей Иосифович, д-р техн. наук, профессор, заведующий кафедрой машин и технологий обработки давлением, Магнитогорский государственный технический университет им. Г.И. Носова», г. Магнитогорск; psipsi@mail.ru. M.N. Samodurova1, mar-samodur@yandex.ru, samodurovamn@susu.ru, N.N. Ogarkov2, ogarkovnikolai@mail.ru, S.I. Platov2, psipsi@mail.ru 1 South Ural State University, Chelyabinsk, Russian Federation, 2 Nosov Magnitogorsk State Technical University, Magnitogorsk, Russian Federation

The first devices for preparing workpieces (bars) of refractory metal powders (tungsten and molybdenum) in the form of dismountable steel dies installed in a hydraulic press of special construction with vertical and horizontal cylinders were developed by the American firm General Electric in 1909. This article considers known and new die and device constructions for molding bars from refractory metal powders developed by scientists of Ural scientific schools.

The results of studying the surfaces roughness of rolls, dies, and workpiece are presented and analyzed. Recommendations are formulated on selecting rational surface finishing methods for rolls and dies and methods for preparation of blanks for drawing. The oil absorption capacity of surfaces depending on their roughness caused by the machining method used is determined. The results can be used for choosing surface finishing methods, tools, and materials, depending on the intended metal-forming process.

Analysis is provided for known and new technology and construction of dies for molding gas-saturated powders of tungsten and carbon powder composites made on the basis of YuUrGU scientist inventions. Gas saturation of tungsten powder is connected with the unusually low bulk density equal to 0.06–0.12 of the density of pore-free tungsten, and small powder particle size within the limits of 1–3 μm. High gas saturation of powder composites based on carbon is determined by the high capacity of carbon for adsorption of gas and liquid vapor molecules at particle surfaces.

The results are provided for research and also development of mill technology and construction with fourroll passes for rolling small section nickel-base superalloys. The design of roll passes, mechanical property test results for rolled bars of nickel-base superalloys at 20°C and working temperatures of 850–950°C, and indicators of stress-rupture strength are provided.

Titanium alloy product manufacturing is traditionally considered to be a rather difficult task. Additive manufacturing technologies, which have recently become quite widespread, can ensure the manufacture of titanium alloys products of an arbitrary geometrical shape. During this study, we have developed a methodology for manufacturing titanium alloys products using additive technologies on FL-Clad-R-4 complex of laser melting of metals by combined Selective Laser Melting (SLM) and Direct Metal Deposition (DMD) methods. Ti&ndash, 6Al&ndash, 4V and Ti&ndash, 4Mo&ndash, 1V alloys were used for the manufacture of samples. We studied the microstructure of the obtained details and measured the microhardness of the samples. We discovered a gradient of the structure throughout the height of the details walls, which is connected with the peculiarities of thermal cycles of the technology used. This affected the microhardness values: in the upper part of the details, the microhardness is 10&ndash, 25% higher (about 500 HV) than in the lower part (about 400 HV). Products made according to the developed technique do not have visible defects and pores. The obtained results indicate the competitiveness of the proposed methodology.

Drop and rotary forgings of molybdenum or tungsten rods and wire rods requires a great number of operations accompanied by significant losses in expensive metals and low quality of half-finished products. Therefore, it is of great importance to develop new effective methods as well as the appropriate equipment for high-quality treatment of molybdenum, tungsten, and their alloys. The paper presents one of the methods—multi-pass rolling with multi-sided reduction of powder sintered blocks. Intensive three- or four-sided reduction of the block leads to a favorable strain-deformation conditions at the point of the applied deformation allowing to obtain the appropriate scheme of that state of the material. As a result, the plasticity of the rolled material increases and its cross-flowing slows down. High plasticity of the material allows to increase the degree of multi-sided reduction of rods or stocks and, therefore, to reduce the total number of treatment operations, to reduce the losses of metals, and to improve the quality of rolled products and their mechanical characteristics. Slowing down the cross-flowing of the metal during multi-sided reduction of its blocks in the process of rolling allows for a more effective deformation, low energy consumption, and cut number of block passes. Thus, four-sided reduction gives the most favorable scheme of the strain-deformation state of the material under the condition of multi-sided, nonuniform reduction of the blocks in the process of rolling.

This work is devoted to the study of the microstructure and the properties of the Cu-W composite coatings deposited using cold spray technology. This process allows fabrication of high-quality coatings on large surfaces of different types of materials. The technology is widely used and investigated due to technological simplicity, wide range of sprayed materials and operating temperatures. However, there are some technological problems which appear when materials with low melting temperatures are sprayed. During softening, the particles adhere to the nozzle walls and block spraying. By the way, it is possible to solve the problem adding some ceramics particles to the spraying mixture of powders. As a result, the formed coating will have better mechanical properties and the technological problem will be solved. The analysis of the general results of the microstructure studies and experiments, and comparison with other coating methods are given. Moreover, the experimental procedure of samples preparation and used equipment are given. It is shown the microstructure before and after heat treatment of the samples sprayed, microhardness measurements, thermal conductivity measurements.

The Russian and foreign technology used since the beginning of the last century to industrially produce collector profiles made of copper-cadmium bronze is characterized by low productivity, large losses of metal, and semifinished and finished products of inferior quality. The technology includes casting and pressing ingots obtain semifinished products of trapezoidal, square, or rectangular cross section, which are then rolled or drawn to obtain billets for subsequent final drawing. The pressing and rolling or drawing of the trapezoidal semifinished products is accompanied by bending of the ribs and twisting of the product, and the quality of the finished profiles is compromised by their curvature. The authors have developed new methods and equipment for rolling collector profiles in tapered rolls to avoid the formation of such defects. Results are reported from tests of the methods, which involve rolling in tapered rolls with intersecting axes.

The compressibility of bars and hydraulically forged workpieces made of tungsten and molybdenum is studied during rotary swaging and rolling in mills with two-, three-, and four-roll passes. The compressibility of molybdenum MCh bars and hydraulically forged molybdenum M-MP workpieces is investigated during rotary swaging and rolling in three- and four-roll passes. The compressibility of tungsten VA and VL bars and hydraulically forged tungsten V-MP workpieces is investigated during rotary swaging and rolling in three- and four-roll passes. The compressibility of the hydraulically forged tungsten V-MP workpieces is analyzed under two- and four-roll pass rolling conditions.

Development of high-speed workpiece stamping technology for objects of domestic designation from iron-based powders is analyzed. Results of experiments performed by the authors are discussed for cold high-speed stamping of objects such as bushes with a conical section made from iron powder grades PZhV3 and PZhV4 followed by sintering, and also by high-speed stamping of these objects. A die construction and methods for preparing workpieces of the bush type with a conical end section proposed by the authors are protected by patents.

The industrial technology which has been used since the beginning of the last century to make products from tungsten powders is still complicated and involves multiple operations. The technology is time-consuming because engineering studies that determine the parameters of the operations of compacting, sintering, welding, and shaping the tungsten compacts need to be performed before the first large batch of commercial products can be made. A factorial experiment showed that these operations can be made less labor-intensive by constructing regression relations for the density of the powder, sample weight, and the forces in the compaction process. New designs of molds have been developed together with a new method of compacting tungsten powder.

Data are provided for particle shape, component and grain size composition, for information about the connection of compact density with compaction pressure for powder materials with special properties based on tungsten and carbon.