The growth in metal intensity of industrial production and the volume of consumption of finished metal products determine the relevance of development and research of energy efficient technological processes aimed at reducing costs by reducing the number of operations while maintaining product performance. In mechanical engineering, the problem of obtaining blanks with increased dimensional and geometric accuracy and complex configuration is solved by using a common method of investment casting. Expansion of the use of such technological approach to produce blanks in mechanical engineering is hindered by a number of physical phenomena associated with the thermal expansion of investment and ceramic materials, which leads to an increase in the product final cost. A significant number of defect-forming factors can be eliminated by applying an innovative solution consisting in the formation of porous removable models by compacting mixtures based on waxy materials. This solves the problem of material shrinkage and increases the crack resistance of ceramic molds, which significantly reduces the share of machining in the overall volume of technological operations. Technical tests of the new method have revealed the reason why the machining of castings cannot be completely eliminated at present. The problem mainly lies in elastic response of compacted material of the model mixture, which, in some cases, affects the increase in the compacts size. This paper considers the effect of initial packing of spherical-shaped elements simulating one- and two-component model mixtures on the stress-strain state of a powder body subjected to unilateral compaction in a rigid cylindrical matrix to technologically justified density values. The results of the experiment are presented in the form of stress-strain relations. Preferable conditions of compact formation with minimal values of elastic response of the compacted material are considered.

Roll pass design of shape rolling rolls is considered from the standpoint of system analysis within “UrFU concept of optimal roll pass design” created in the Chair “Metal Forming” of the Ural Federal University. Roll pass design as a technological system can be changed in two methods: 1) changing the structure of the system which corresponds to a change in the groove shape; 2) changing the control of the system, which corresponds to changing reduction through the pass in the grooves, that is, by changing the reduction mode. Roll pass design that compose of the definite grooves and realize the definite reduction mode, which assures of optimal properties of preassigned objective function depending on the specified parameters, is considered optimal. General conception of two-stage optimization of roll pass design: consistent conduct of optimization of roll pass design scheme (first stage of optimization) and mode of reduction (second stage of optimization), was considered in previous reports. Procedures of formation of optimization space for first stage – space of virtual schemes of roll pass design generated by the special generator and set of all possible types of grooves that can be used at this particular stage of rolling, were also described. To calculate the objective function of the optimality criterion of the roll pass design scheme, the authors introduced the concept of “space of grooves efficiency”. Formation of this space is carried out using a formalized procedure for expert evaluation of the degree of influence of various permissible forms of grooves used in roll pass design on the diverse technological, economic and other characteristics of a particular rolling mill. The objective function is calculated as variance of integral performance indicators of the grooves included in the roll pass design relative to the hypothetical “ideal” groove with the best values of the selected performance indicators. The roll pass design scheme corresponding to the minimum value of the objective function is considered the best.

The purpose of this work was to analyze the effect of a heat-insulating insert, as well as the flow rate and temperature of natural gas on the processes occurring in blast channel of an air tuyere. The paper analyzes the results of industrial and numerical experiments obtained by different researchers on the use of various methods for increasing the completeness of combustion reaction within the air tuyere of natural gas (NG) fed into it: increase of NG flow rate; increase of NG temperature; the use of heat-insulating inserts installed in the inner glass of the air tuyere. Using the Ansys Fluent software complex, the effect of a heat-insulating insert and increase in NG flow rate on the temperature and composition of gases leaving the tuyere of blast furnace no. 5 of PJSC Severstal was studied. It was found that with an increase in NG flow rate from 0.283 to 0.328 kg/s, the temperature of the gas medium at the tuyere outlet decreases by 6 °С for the variant without an insert and increases by 3 °С for the variant with it. When studying the effect of a heat-insulating insert and increase in NG temperature (in different combinations) on the processes occurring in a tuyere, it was found that temperature of the gaseous medium at the tuyere outlet in case of using a heat-insulating insert without NG heating is slightly higher than when NG is heated to 200 °С without inserts. However, the effect of NG heating in the presence of an insert is significantly higher than without it – there is mutual amplification of two factors influencing the completeness of NG combustion within the tuyere, accompanied by protection of the tuyere inner nozzle from burnout.

In the article, the tests of the medical alloy Co – 28Cr – 6Mo after homogenization for uniaxial compression at temperatures of 1000, 1100 and 1200 °C and strain rates of 1, 10, and 50 s­^–1 were carried out using the Gleeble System 3800. The stress-strain curves describing the alloy deformation behavior were obtained. The calculations of hot deformation parameters (activation energy, Zener-Hollomon parameter) were performed using three models (power-law, exponential, and hyperbolic sine function) describing the flow stress. The highest degree of convergence was shown by the calculation results based on the power function and the hyperbolic sine function. These models can be used to accurately calculate the flow stress at given temperature and strain rate parameters, or to simulate the deformation process. Also, based on processing maps, the authors developed the deformation-speed modes of hot deformation of the Co – 28Cr – 6Mo alloy. It will make it possible to choose the optimal rolling modes in the future. According to the data obtained, favorable temperature-speed conditions for hot deformation are shifted as deformation accumulates to the region of high temperatures and low strain rates. At the same time, the extremely unfavorable zone with negative values of the ξ-criterion, which appears at e = 0.3 – 0.4, continues to grow quite significantly with an increase in the deformation effect. Hot deformation of the Co – 28Cr – 6Mo alloy at low compression ratios (e < 0.2) is more expedient to perform at temperatures above 1150 °C and strain rates of at least 20 s^–1. With an increase in deformation degree, it is necessary to choose lower strain rates (1 – 5 s^–1) and higher deformation temperature.

The authors investigated tribological characteristics, phase composition of friction surfaces and microhardness of near-surface regions of WC – (Fe – Mn – C) composites with a two-phase (γ + α′) matrix containing 4 % wt. Mn (WC – 80G4), and a single-phase matrix of γ-iron containing 20 % wt. Mn (WC – 80G20) after friction on a disk of high-speed steel at a contact pressure of 5 MPa and sliding speeds in the range from 10 to 37 m/s. The wear intensity of WC – 80G4 and WC – 80G20 increased with increasing sliding speed, while the wear rate of WC – 80G20 at fixed sliding speeds was approximately three times higher than that of WC – 80G4. The values of the friction coefficient decrease with increasing sliding speed in such a way that at fixed sliding speeds the values of the friction coefficient of WC – 80G4 were lower than those of WC – 80G20. The amount of complex oxide FeWO₄ formed during tribo-oxidation of the composites’ worn surface increased with the sliding speed and was directly proportional to the wear intensity and inversely proportional to the friction coefficient values. At fixed sliding speeds, tribooxidation of WC – 80G4 leads to the formation of a larger amount of FeWO₄ on the friction surface, compared to the WC – 80G20 composite. Indentation of worn surfaces with a Vickers pyramid showed that the nature of indentation resistance of tribolayers formed at high sliding speeds (30 m/s and 37 m/s) differs from that for tribolayers obtained at relatively low sliding speeds (10 and 20 m/s), namely, the friction surfaces after high sliding speeds were characterized by a more tough behavior. Measurement of microhardness values of the WC – 80G4 and WC – 80G20 composites obtained after indentation from the friction surface into the depth of the material recorded the fact of hardening of the near-surface regions of the WC – 80G4 composites and, on the contrary, softening in the case of WC – 80G20. Thus, under conditions of strong heating and severe plastic deformation of the surface, structural-phase state of the substrate of WC – (Fe – Mn – C) composites, on which this viscous protective tribolayer is formed, turns out to be a very important factor. It is the two-phase (γ + α′) steel matrix that, under conditions of strong frictional heating, provides the conditions for effective formation of a heterophase composite layer that reduces the friction coefficient and has a high resistance to fracture upon indentation.

The main components of metallurgical slags are iron compounds, which are extracted by reduction smelting. The process of obtaining various products based on iron and slags of different compositions (alumocalcium self-crumbling, etc.) can be implemented in several ways. It is important to use a mode of smelting and cooling of the alumocalcium slag formed during melting in the furnace that ensures its most complete spontaneous crumbling and high rates of extraction of REM from it. Synthetic slags having a phase composition similar to industrial samples after the smelting of iron ores were selected for the experiments. The simulated samples correspond to the dicalcium silicate primary crystallisation region on the ternary phase diagram of the CaO – SiO₂ – Al₂O₃ system. After crumbling, the slag was subjected to sieve analysis using a mechanical sieve. Slags with a silicon modulus k = 2.0 that actively crumbled during cooling were used in the experiments. A higher silicon modulus results in a lower crumblability. It was established that it is impossible to precisely limit the composition areas of the crumbling slags at specific cooling rates. The studies showed that the crumblability of slags improves when moving towards the centre of the dicalcium silicate region. The composition of the slags is close to the composition of the points located in the area bounded by the lines 2CaO·SiO₂ – 2CaO·Al₂O₃ and 2CaO·SiO₂ – 12CaO·7Al₂O₃ on one side and by the lines of the silicon modulus no higher than 2.85 – 3.00 on the other side. The granulometric composition is almost independent of the cooling rate. The temperature mode from smelting to cooling affects the crumblability of the slags.  The most promising are slags with a silicon modulus in the range of 2.85 – 3.00 close to the phase triangle 12CaO·7Al₂O₃ – 2CaO·SiO₂ – 2CaO·Al₂O₃.

The article presents the results of evaluation of the impact of teeming method and rate on solidification and formation of the axial zone of large ingots. The research is based on a physical simulation. With this aim a laboratory-scale plant (a crystallization mould) was designed and built which enabled to visualize and monitor solidification and structural formation of the model ingots. Sodium thiosulphate (crystal hyposulphite) – Na₂S₂O₃·5H₂O was used as a modeling solution. Matching of the processes in the model and in real industrial conditions of ingot teeming was assessed with similarity criteria obtained on the basis of the dimension theory with consideration of the physical and chemical processes in the ingot during its teeming and crystallization. Two methods – downhill casting and uphill casting – were used to teem the melt into the mould. During teeming the geometry and technological parameters of the model ingots remained unchanged while the teeming rate was altered. Length and medium width of the model ingot axial zone were measured. The thermal profiling of the surface of the mould model was monitored over the entire period of solidification to evaluate the thermal field alteration while the ingot was teemed and crystallized. Thermal imaging processing made it possible to observe temperature changes of the surface of the model mould from top to bottom for downhill cast ingots teemed at different rates. The results obtained demonstrate that teeming rate has a noticeable impact on the axial zone length. It was established that a decreased rate leads to an increased directionality of crystallization and improvement of the ingot axial zone structure.

The paper considers results of the analysis of operability of the transporting equipment at agglomeration shops of the Ural metallurgical enterprises. It was established that during long-term operation of the hopper car for transportation of hot agglomerate, dust settles on its walls, growths of accumulated dust are formed, and the effect of vaulting occurs. Due to compaction and increase in dust layer, useful volume of the hopper car decreases which in turn leads to the need to carry out dangerous work to clean the dust directly inside the hopper car. Manual labor is used for this purpose. Such works are very dangerous for human health due to high dust content and high injury risk. In order to eliminate the problem of vaulting and accumulation of dust on the car walls, it is proposed to use the installation of two vibrating devices of the “False wall” type together with a vibrating neck (vibrating beam). The vibrating element of the device is a plate that is mounted on the inner wall on flexible suspensions (round link chain). Rubber shock absorbers are installed between the plate and the hopper wall, which are used as rubber-fabric conveyor belt. A vibrator is mounted to the plate through the support post, and the transmission of vibrations to the agglomerate is carried out using a vibrating hump, which is welded to the plate (false wall). Introduction of the designed device ensures reduction of unplanned downtime of the hopper cars team and rejection of hazardous to human health work related to the bunkers cleaning. The economic calculation confirms feasibility of the ongoing measures for reengineering of hopper cars in the conditions of agglomerate production at metallurgical enterprises.

The article reveals one small page from the history of development of metallurgical science and technology in the Soviet Union. We describe the establishment of scientific contacts between American and Soviet metallurgical scientists in the second half of the 1950s. The successes of the  USSR in the space race demonstrated to the Western countries the real scientific and economic power of the country, showing the unconstructiveness of the policy of isolation and the benefits of economic cooperation. American specialists discovered the high level of development of metallurgical science and technology in the USSR. Ural Polytechnical Institute (UPI) was one of those universities visited by American guests. This article is devoted to this page of the history; it is a  continuation of the authors’ material published earlier.