The authors made a brief review of recent publications by foreign and domestic researchers on the structure, phase composition, and properties of films and coatings of five-component high-entropy alloys (HEA) on various substrates and modification of the HEA surface by various types of processing. The main methods of applying films and coatings are considered: magnetron sputtering, thermal sputtering, laser sputtering, and electrodeposition. Particular attention is paid to the deposition of coatings on stainless steels and titanium alloys. The positive change in the tribological, strength properties, and corrosion resistance of film coatings in a wide temperature range is analyzed and possible causes of the observed effects are discussed. The role of solid solution strengthening, formation of fine-grained structure, and the formation of oxide layers enriched with one of the HEA components were taken into account. The authors identified new methods for applying coatings from HEA and subsequent processing. Using Nb and Ti doping as an example, their role in increasing microhardness, wear resistance, and reducing the friction coefficient in coatings were revealed. Electrolytic polishing, electroerosive machining, mechanical polishing and their combination are considered among the methods of HEA surface treatment. A number of works propose a method of powder borating to increase the surface strength and wear resistance of HEAs. The paper considers analysis of works on electron-beam processing as one of the promising and high efficient methods of HEA surface hardening.

The paper presents the results of a study of electroplastic effect in metastable high-alloyed austenitic-martensitic steel in strip form with the thickness of 0.3 mm during plastic deformation with current of different modes and regimes. Choice of the research material is due to manifestation of the TRIP effect in it, caused by martensitic transformation during deformation. The ratio of volume fractions of austenite and martensite in the steel before deformation was 50:50. Deformation behavior of the steel was studied by stress-strain curves and mechanical properties at room temperature in static tension with current by short single pulses of large density, as well as multipulse current with frequency of 1000 Hz and direct current. Microstructure in the initial, before tension, state was investigated by optical and transmission microscopy. It consists of large equiaxed grains of austenite and twinned martensite up to 80 µm in size. Phase composition of the steel before and after tension with and without current was studied by X-ray diffraction. Tensile deformation without current promotes martensitic transformation and increases the volume fraction of martensite from 50 to 82 %. The introduction of single current pulses does not influence the TRIP effect, causes power surges and confirms the occurrence of electroplastic effect. Current mode has a strong influence on manifestation of the TRIP effect, suppressing it at multipulse and direct current and causing a sharp decrease in tensile strength, yield stress, and elongation to failure. Tension with current stabilizes the austenite and reduces content of the formed martensite up to 72 % in multi-pulse mode and up to 50 % when using direct current.

The study concerns the macroscopic localization of plastic strain during uniaxial tension of Hadfield steel (Fe – 13 %, Mn – 1.03 % C) monocrystals. At the easy glide stage, significant differences were noted in the nature of plastic strain macrolocalization. All strain localization patterns observed in these cases can be divided into two types. The first type of strain localization corresponds to nucleation at the upper yield point and to further propagation of the strain front. This gradually transforms the specimen material from an undeformed state to a deformed one. This is most clearly manifested in monocrystals oriented along tensile axes \([\bar{3}77]\) and \([\bar{3}55]\), where the localization of strains is represented by a single zone in the yield area. This strain front passes through the specimen volume only once as a Chernov-Lüders band. In this case, the material flows without hardening until all of its elements have been converted to a strain state. Single strain localization zones are also observed at easy glide stages and the yield point in Hadfield steel monocrystals oriented along tensile axes \([\bar{1}23]\) and \([012]\). In the second type of localization a synchronous movement of several strain centers occurs in the specimen at the easy glide stage. The movement may be unidirectional or counteracting. Further strain of Hadfield steel monocrystals oriented along tensile axes \([\bar{3}55]\) or \([012]\) results in the movement of two strain localization centers at the easy glide stage. In monocrystals oriented along axis \([\bar{1}11]\), the strain localization pattern is represented as four localized strain centers. Consequently, the synchronous movement of strain fronts occurs in the already strained material. The number of active glide or twinning systems in the tensile strain of monocrystals studied can be viewed as a reason for the difference between the two types of macrostrain localization at the easy glide stage and the yield point.

The authors investigated the features of structural-phase state of a composite based on stainless austenitic steel with addition of 25 % (vol.) aluminum bronze. The composite was obtained by electron beam additive technology with simultaneous feeding of two wires. The paper considers analysis of the structural-phase state and mechanical characteristics. The contributions of various mechanisms to the composite hardening were evaluated. It was established that a multiphase structure is formed in the steel – 25 % bronze composite, which consists of 43.9 % austenite, 32.0 % ferrite and 24.2 % bronze. Dispersion-hardened copper particles are isolated in austenite grains, volume fraction of which counts 47 %. Dispersion-hardened NiAl particles with a volume fraction of 20 % are isolated in ferrite grains. Transmission electron microscopy data indicate a coherent conjugation of arrays of dispersion-hardened particles with the matrix. Such a composite structure provides an increase in the tensile strength by an average of 50 % compared to austenitic steel obtained by electron beam additive technology without the addition of aluminum bronze. It was found that the contributions of various hardening mechanisms to yield strength of austenite, ferrite and bronze amounted to 959.3, 972.7 and 408.7 MPa, respectively. Bronze grains do not make a significant contribution to increase in yield strength of the composite, except for its increase due to dislocation hardening. The main contributions to increase in the composite yield strength are made by austenite grains due to grain-boundary, dispersion and dislocation hardening and by ferrite grains due to grain-boundary, solid-solution and dislocation hardening.

For smelting of high-quality metal for transport purposes, it is necessary to limit the content of harmful impurities in it, including dissolved gases. For example, hydrogen content in the finished product should not exceed more than 2 ppm. In order to obtain low residual hydrogen content in steel in the converter shop of JSC EVRAZ NTMK, the transport metal is processed at circulating vacuuming plants. Circulating vacuum degasser is the last stage of steel processing before casting on continuous casting machine, so it is important to study and improve the technological processes in it. To investigate the physico-chemical processes occurring in this metallurgical unit, a hydrodynamic model of the system circulating vacuum degasser – steel ladle was created. Based on theoretical calculations and experiments conducted on a physical model, the main dependencies between the structural and technological parameters of the metallurgical unit were determined. The resulting equation makes it possible to determine the rate of metal circulation in vacuum chamber depending on gas flow rate supplied to inlet snorkel and its inner diameter at circulating vacuuming plants designed for metal processing in steel ladles with a capacity of 140 – 180 tons. Theoretical calculations were confirmed by practical smelting in a steelmaking unit. It is shown that during the wear of lining of the inlet snorkel vacuum chamber, in order to obtain stable residual hydrogen content, it is necessary to make changes in the technological process of vacuuming. Additionally, rational technological parameters of steel processing at the circulating vacuuming plant were determined on the basis of theoretical calculations.

Technological features of powdered reagents injection into the melt using a submersible tuyere were investigated for the research and development of the main provisions of rail steel out–of-furnace treatment in a ladle-furnace. Authors analyzed the characteristics of influence of a directed heat flow through the tuyere conditional separation wall from metal to two-phase gas-powder flow under purging conditions. Using numerical methods, were determined the parameters of influence of the submersible tuyere surface temperature on characteristics of the transporting gas, concentration of the powder and its density, and on characteristics of the gas-powder flow, including the aerodynamic drag coefficient, pressure of the transporting gas, difference in phase velocities, equivalent diameter, and particle shape coefficient. The obtained experimental results show that at the same flow rate of the transporting gas, more significant heat flows, ensuring stable operation of the blowing device, are created by using a lighter gas (nitrogen), while the diameter of powdered particles does not affect the amount of heat transferred from the tuyere wall to the transporting gas. It was established that when using submersible tuyeres and heating the gas–powder flow to a temperature of 500 – 600 °C, the strength of the interfacial interaction changes by 2 to 10 times depending on the particle shape coefficient, concentration of the injected powder, pressure of the transporting gas, difference in phase velocities and density of the powder.

Metallurgical, construction and mining industries are based on the process of grinding various materials. The main method of primary preparation of raw materials is crushing of the extracted ore. Up to 4 % of the world’s electricity production is spent annually on crushing rocks to obtain the necessary fraction of material, and for a single mine, the share of energy consumption for crushing can reach 50 % of the annual volume. In addition to spending electricity directly on rocks destruction, some of it is spent on creating a power reserve for a crushing machine (hereinafter referred to as a crusher) due to the fact that currently there is no single method of theoretical calculation of the power of its electric drive, no single method of determining energy costs for rocks destruction. It is known that raw materials extracted from different deposits have different physical and mechanical properties, which has a significant impact on the grinding process. However, difference in power of electric drive of crushing machines is due to the difference in their standard sizes, and the geography of their application is taken into account by the creation of the above-mentioned power reserve. The above factors have a negative impact on the operating costs of metallurgical industry enterprises. The article discusses some designs of crushers in which the destruction of the crushed piece occurs as a result of complex stress state. New design of a cone crusher with stops is proposed, which allows reducing energy costs for crushing materials. Due to the presence of stops and simple kinematics of the working body movement, reduction in the power necessary for the destruction of pieces of brittle materials, regardless of their properties, is achieved. At the same time, in crushed pieces destroyed in a cone crusher with stops, it is possible to create a shear stress state, in which theoretically a reduction in power required for crushing brittle materials is achieved by 2 times in comparison with compression crushers. The conditions of occurrence of shear stress state in crushed pieces during their crushing in a cone crusher with stops are described. The authors give recommendations for the reconstruction of these conditions.

The stress state (SS) of multilayer shell mould (SM) is significantly influenced by its morphological structure, its variants, and the connections between the contacting layers. The purpose of this work is to establish the effect of sliding without friction of one of the layers of SS relative to the neighboring contacting layer on SS of the multilayer SM. The process of determining the stress-strain state (SSS) in the SM is modeled when it is filled with steel, in which there is a surface between the layers, where one layer of the SM is completely sliding relative to the adjacent neighboring layer. The task is to find the geometric location of a given surface by thickness of SM from the condition of the formulated objective function with the corresponding system of constraints. The construction of the mathematical model is based on equations of the linear theory of elasticity, the equations of thermal conductivity, solution of which is carried out by a proven numerical method. In the axisymmetric formulation, a complex three-component system is considered: liquid metal, solid metal, ceramic SM. Solid metal and SM are considered to be isotropic. Crack resistance of the SM is estimated by the stresses arising in it. On contact with the support filler (SF), it is possible to move the SM surface from the SF during the liquid metal cooling. In this case, the contact problem is solved – reassignment of the boundary conditions. An algorithm for solving the problem is compiled. The results of numerical modeling are displayed graphically in the form of plots. A detailed analysis of the obtained results was carried out. The inconsistency of manufacturing such a multilayer mould is shown. The results of the research can be useful in calculations of other functional multilayer shell systems.