The paper describes the possibility of using cored wire for wear­resistant hardfacing containing waste (dust of gas­cleaners) from the production of silica manganese and aluminum. Hardfacing was carried out using a submerged welding tractor made of silica manganese slag produced by the West Siberian Electrometallurgical Plant. The wear rate on the samples was determined on 2070 CMT­1 machine. The method for it is based on change in the sample mass during the disc – pad test. Chemical composition of the deposited metal was determined by X­ray fluorescence method on XRF­1800 spectrometer and by the atomic emission method on DFS­71 spectrometer. The hardness of the deposited layers was measured using METH­DO hardness tester. Evaluation of the quantity of nonmetallic inclusions was made according to GOST 1778 – 70 using an OLYMPUS GX­51 optical microscope. The coefficient of manganese recovery was found at different ratios of components. This coefficient is associated with the reduction of manganese oxide from manganese­containing flux (due to the carbon contained in the cored wire). With a significant excess of carbon in the cored wire from manganese­containing flux, recovery of manganese exceeds 100 %. The process of manganese recovery was determined by filling coefficient of the cored wire, amount of the carbon­containing material in the charge, and carbon content in the electric­arc coating itself. The deposited metal contains non­deformable silicates and point oxides. Contamination by oxide nonmetallic inclusions of the deposited metal is small. The presence of these non­metallic inclusions does not significantly affect the operational characteristics of the deposited layer.

The article presents the results of surface hardening of tungsten­carbide hard alloys carried out using concentrated energy flows. The VK6­OM alloy with a thickness of 20 μm is applied to the hard alloy VK10KS by the method of electric spark treatment. In this case, a surface hardened layer consisting of W₂C is obtained. The hardness of the resulting layer is 22,000 MPa and the friction coefficient is 0.23 (compared to the friction coefficient of the original hard alloy of 0.41); strong but insufficiently wear­resistant base is preserved. In the work, a surface layer on a hard alloy VK10KS with a thickness of 40 μm and phase composition of TiC and W2C was obtained by the method of single­component electro­explosive alloying with titanium. The nanohardness of this layer is 25,000 MPa and the friction coefficient is 0.14. A surface layer with thickness of 3 – 4 μm and phase composition of TiB₂ , TiC, W₂C was obtained on the hard alloy VK10KS by the method of multicomponent electro­explosive alloying with titanium and boron. The nanohardness of the hardened layer is 27,500 MPa and the friction coefficient is 0.10. Applying the technique of separate cathodes, an ion­plasma TiN + ZrN coating (50 % Ti + 50 % Zr) with a thickness of 20 μm was applied to the surface of the VK10KS hard alloy. Nitrogen was used as the reaction gas. The nanohardness of the surface layer hardened in this way is 38,500 MPa and the friction coefficient of is 0.07. Ion­plasma TiN + ZrN coating has good adhesion to the substrate. The use of the proposed methods of surface hardening of VK10KS hard alloy makes it possible to choose one of the hardening methods, based on operating conditions of the carbide tool, to extend its operational life, as well as to save scarce materials (tungsten and cobalt).

The structure, phase and chemical composition of a heat­resistant alloy formed by plasma in a nitrogen medium with subsequent high­ temperature tempering have been studied by scanning electron microscopy and microrentgenospectral analysis. It was found that in the deposited alloy, the main phases are a solid solution of α­iron and carbonitrides based on iron, tungsten, chromium, molybdenum, and aluminum (Fe6W6NC and AlN). High­temperature treatment (four­fold high­temperature tempering at a temperature of 580 °C for 1 h) of the deposited coating leads to an increase in the crystal lattice parameters (from 2.866 to 2.89 Å) and in the sizes of coherent scattering regions (from 25 to 100 nm), and to a decrease in internal elastic stresses (from 1000 to 600 MPa). A pronounced oriented dendritic structure is observed on the deposited surface. After surfacing and high­temperature tempering, the oriented dendritic structure is practically not visible. The distribution of microhardness over the depth of the deposited layer in the state after surfacing is characterized by a significant spread at its high average value on the surface of 4.142 GPa (dispersion 1.0956) and the middle part of the surfacing – 5.153 GPa (dispersion 1.5697). The spread of microhardness values is associated with the complex thermal effect of multilayer plasma surfacing along a helical line and mixing of the substrate material with the surfacing coating. High-temperature tempering leads to an equalization of the microhardness values and an increase in its average value to 5.7 – 6.5 GPa. The nature of hardening of the deposited heat­ resistant metal of high hardness, additionally alloyed with nitrogen and aluminum, was clarified. The main hardening of the deposited metal occurs at high temperature tempering due to an increase in the carbide and carbonitride phases and the formation of fine aluminum nitride.

A comparative quantitative analysis of the physical mechanisms of hardening of rails surface layers after extremely long­term operation has been performed. The method is based on previously established patterns of formation of structural-phase states and mechanical properties of differentially hardened long­length rails produced by JSC “EVRAZ ZSMK” at a depth of up to 10 mm in the cutting of rails along the central axis and cutting out after the missed tonnage of 1411 million tons. The calculations took into account the volume fractions and characteristics of a particular type of substructure. Increase in microhardness and hardness of the surface layers of the rails subjected to ultra­long operation on the experimental ring of the Russian Railways is multifactorial and is determined by superposition of a number of physical mechanisms. The contributions are estimated due to friction of the matrix lattice, internal phase boundaries, dislocation substructure, presence of carbide particles, internal stress fields, solid hardening, and pearlitic component of the steel structure. Regardless of the analysis direction (along the central axis of the head or along the axis of symmetry of the chip), strength of the rails metal depends on the distance to the surface: it increases as it approaches the top of the head. The most significant physical mechanisms have been established, which provide high strength properties of the metal of the rail head subjected to extremely long­term operation. In the subsurface layer (located at a depth of 2 – 10 mm) of the rail head, the most significant physical mechanisms are dislocation mechanism, due to the interaction of moving dislocations with stationary dislocations (dislocations of the “forest”); in the surface layer of the rail head, substructural mechanism, due to the interaction of dislocations with small­angle boundaries of fragments and subgrains of a nanometer–sized polygon. A comparison with the quantitative values of the rail hardening mechanisms after the missed tonnage of 691.8 million tons was carried out. It is shown that an increase in the missed tonnage in the range of 691.8 – 1411 million tons leads to a significant (1.5 – 2.0 times) increase in strength.

In order to identify bottlenecks in the equipment operation and accumulate data for the development of organizational and technical measures to reduce unplanned equipment downtime, JSC “Vyksa Metallurgical Plant” keeps records of downtime of the main technological equipment. All equipment downtime is recorded by production personnel in the automated analysis system of the workshop. Reliability specialists in the workshops have classified all units into criticality categories, which are presented in the form of a matrix that includes two groups of indicators: 1) severity of the consequences – personnel safety, safety of equipment and environment, production losses, troubleshooting costs; 2) probability of occurrence – high, medium, low, or very low. When determining the criticality assessment of an equipment unit, the most critical case of equipment failure and the worst one are considered. Classification of equipment by criticality categories is used to rank equipment in terms of reliability. The article considers the criteria for operability of machine parts, as well as the main software complexes for strength analysis that exist today. Two have been selected that will be used as strength analysis tools. The analysis of equipment unplanned downtime due to the destruction of parts was carried out on the example of the wheel rolling shop of JSC “Vyksa Metallurgical Plant”, unloaded from the shop automatic analysis system. The authors proposed the directions of application of the selected strength analysis tools and made the strength analysis of equipment parts in order to increase their structural reliability. An assessment of the potential economic effect of introduction of strength analysis tools showed the feasibility of using this innovative approach leading to downtime reduction.

One of the main engineering industries is the processing of metals by pressure. Its purpose is the formation of products from metal blanks of simple forms. An important role in this case belongs to the technology of sheet rolling. The solution of issues related to the choice of optimal modes of sheet rolling is relevant for specialists in the field under consideration. The process of rolling metal products is special, since the contact stresses can exceed the deformation resistance of rolled metal by several times. The tasks of predicting the quality of products, taking into account the prevention of sheet metal continuity defects, as well as the study of technological operations reliability of rolling process are associated with the solution of industrial and scientific problems in this area. Domestic and foreign researchers have noted a significant influence of external friction in the deformation center on the technological parameters of rolling process and quality of the resulting metal products. It is known that rolling is impossible without external friction between metal and roll. The reduction of friction provides an opportunity to increase the economic indicators of sheet rolling, and the rolling production technology itself has significant opportunities for further improvement. Technology of sheet rolling in the conditions of hydrodynamic friction mode allows modeling of friction conditions in the deformation zone. Taking into account the hydrodynamic effect of lubrication allows us to assess the influence of technological factors on the conditions of contact friction during metal pressure treatment and to control the rolling process. Regularities of the flow of liquid Newtonian lubricant are investigated, taking into account features of the deformation zone geometry during sheet rolling. Pumping capacity of the lubricating wedge during rolling is determined, which allows us to explain the regularities of lubrication influence on friction conditions. As an example, the results of calculation of the lubricant pressure depending on the rolling speed are presented. The rolling speeds that provide a liquid friction mode are given. The obtained relations allow us to estimate the influence of contact friction on technological parameters of sheet rolling and can be used in technological calculations of this process

The well­known energy­efficient method of crushing in a single­roll crushing machine with smooth rolls, in which a complex stress state is created in the destroyed piece, has a significant disadvantage – low productivity due to a limited degree of crushing. In order to increase productivity, single­roll crushing machines are equipped with stop blocks on the roll, which ensure the forced supply of the destroyed material to the crushing zone. The maximum possible number of stop blocks should be installed on the roll, and the condition of guaranteed feeding of the piece into the fracture zone must be met. The developed mathematical model allows one to calculate the maximum possible number of stop blocks, which ensures guaranteed nipping of the original piece into the destruction zone.

The theoretical substantiation was carried out for increasing the efficiency of converter gases afterburning in the unit with a two­tier supply of multi­pulse oxygen jets and combustion of CO to CO₂ in the channel flow of gases leaving the reaction zone. The authors made the thermodynamic analysis of the process of exhaust gases afterburning in converter cavity when using two­tier oxygen lances for refining. It is shown that when oxygen gas jets are blown through the upper­tier nozzles with a flow rate of 10 – 40 % of the total minute flow rate, a sufficiently complete afterburning of carbon monoxide CO is not provided. The limiting factors are the uneven amount and disorganized output of the CO formed in the reaction zones during various operation periods, low efficiency of mixing the waste stream with high­speed gas jets and an excessively excessive amount of oxygen supplied for afterburning, insufficient mixing of the components of the gas phase and low reaction rate. It is shown that when the conditions are provided for CO afterburning to the concentration ratio in the gas phase, temperature of the exhaust gas in the converter cavity can increase from 1800 to 2000 K, then the thermal effect of the exothermic reaction decreases. The amount of oxygen injected for CO afterburning must correspond to the residual carbon content in the metal at m³/min ≈ 100 [С_ост ] %. Excess of oxygen in the gas phase and presence of a significant amount of neutral gas significantly reduce the utilization rate of the generated heat in the unit.

It is known that the maximum heat losses in a water­cooled tuyere of a blast furnace are in the blowing channel. An effective way to reduce them is to install a heat­insulating ceramic insert. Such inserts installed in the inner cup of air tuyeres for the blast furnace no. 5 of PJSC “Severstal” reduce heat losses through the tuyere by 30 %, and inserts, which, in addition, insulate most of the inner surface of the snout part, further reduce heat losses through the tuyere by 26.2 %. The ANSYS software was used to study the effect of design parameters on thermal processes in a blast furnace tuyere with heat­insulating insert. To make the simulation more realistic the entire air tuyere, including water­cooling circuit, was considered as the modeling object. Protrusion of the insert into the blowing channel by 2 mm improves the mixing of natural gas and blast, promotes gas combustion, which leads to an increase in heat losses through the blowing channel and a decrease in resistance of the insert. To increase durability of the insert and reduce heat losses through the blowing channel, it is justified to use an elongated insert with a thickness varying from 13 to 8 mm in the blowing direction, which does not protrude into the blowing channel, having an angle between the normal to the side of the inner cup and the axis of the hole for natural gas supplying about 30°. It is shown that to obtain the maximum heat content of the blast, which is influenced by the combustion of natural gas and heat losses with cooling water in the blowing channel, it is preferable to have an elongated insert of variable thickness, varying from 10 to 8 mm in the blowing direction, and axis of the hole for natural gas supply perpendicular to the wall of the inner cup.