The paper continues the previous authors’ works in the field of wet wire drawing. The process of wet fine brass-plated steel wire drawing is considered. The subject of the paper is increase of the wire die wearability. The analysis of various wire drawing tools (hard alloy dies, synthetic diamond dies, natural diamond dies) was carried out for the relevance of its application for small diameter wire drawing. The authors studied the wire die wearability. The research methodology is presented, which include the procedure and conditions for measurements, industrial equipment and type of wire drawing machine. In the paper, the comparative analysis of the experimental data with the results of other authors for similar wire drawing tool was carried out. The authors calculated the main characteristics of the wire die wearability distribution (asymmetry, kurtosis, coefficient of variation). A statistical analysis of the array of experimental data for selection of more than 500 samples was performed. A high correlation of the drawing die wearability with the ratio of breaking stress to draw stress and a weak correlation with the drawing force and stress were revealed. The highest and most stable die life results are achieved when ratio of breaking stress to draw stress has values of 1.9 – 2.5. A formula was proposed for determining the optimal value of the ratio of breaking stress to draw stress, depending on the wire diameter. The formula allows one to determine the maximum die wearability values, depending on the wire drawing schedule. The work results can be used when designing new wet wire drawing schedules using synthetic diamond dies.

The international metallurgical World Steel Association has published new data that reviewing the situation in the global steel market. According to the published data for 2021 the production of steel on the world market decreased by 1 % (to 1.83 billion tons). The reduction in steel production on the world stage is the result of sharp fluctuations in market conditions associated with the pandemic. If it is necessary to urgently increase the volume of rolled metal production, the issues of uniformity of metal heating before rolling, stamping and forging, as well as improving the thermal operation of devices for heating the surface of slabs (which will simplify the design of heating devices, reduce the cost of heating and construction), are still relevant. One way to improve the heating process and increase the production of rolled metal is to use jet heating. This paper shows the results of modeling metal heating with nitrogen jets.

The results of observation of steelmaking oxidation stage at EAF-135 were analyzed with automated control system of the electrical characteristics. There are three main zones in the furnace working space, which differ by the aggregate state of the materials in them: arc discharge, melt and foamed slag. The distribution data of electric power over the furnace zones is given. There is active powers asymmetry of the arcs under single electrodes affected by asymmetry of the short network. It is shown that the main factors impacting the melt and slag resistances are oxygen blow and electrode movement. The authors studied the influence of magnesia flux feeds on the melt resistance. These feeds correspond to a sharp increase and a subsequent gradual decrease in resistance, and the time for assimilation of additives does not exceed one minute. The average electrical parameters of the working space zones are given for the EAF-135 at single heats. A comparison was made of the nature of change in the arc discharge power and the change in the melt temperature. The profiles match of changes in these characteristics to an increase in the arc power corresponds to increase in the melt temperature. An attempt to correlate FeO content in the slag with the arc power did not give a positive result. However, this methodology should be tested under conditions of steel refining in a ladle-furnace unit. It is noted that the parameter control at changing of the electrical parameters of the arc and slag zones due to the overwhelming influence of intense oxygen blast, melt mixing and electrode displacement does not meet the reliability criterion.

A key stage in ferronickel production is sulfate-chlorination roasting, after which and at subsequent stages (up to the final product) exhaust gases are formed in the system accompanied by dust and metal chloride vapors outlet in roasting furnace. Enrichment of wastes during their removal with condensed chlorides indicates a decrease in the efficiency of sulfate-chlorination roasting. Therefore, the control of mineral chlorine in filter sediments is important both from the standpoint of environmental monitoring and evaluation of the technological process efficiency. In order to determine mineral chlorine in dusty waste during the ferronickel production, a quantitative chemical analysis procedure based on the ionometric method was developed in the testing laboratory of the South Ural Nickel Plant. This paper proposes a procedure for estimating the results uncertainty in determining chlorine in the sample. It consists of the following steps: compiling a mathematical model to determine the chloride-ion mass fraction, estimating the input quantities in the mathematical model and their uncertainties, estimating the output quantities in the mathematical model and their uncertainties, budgeting for uncertainty, determining the expanded uncertainty and presenting the results. The paper considers the results of calculating the total expanded uncertainty in determining the chloride-ion mass fraction – U(X_Cl– ) = ±9.4 % (kp = 2, P = 95 %) – for the samples with chlorine mass fraction from 0.4 to 0.8 %. Application of the proposed methodology in calculating uncertainty ensures reliable results in determining chlorine in dusty wastes of ferronickel production, which has a positive effect on the technological process and environmental monitoring efficiency.

The method of electric arc metallization has both undeniable advantages and some disadvantages. For example, there is a burnout of alloying elements and a high content of oxides in the applied coating. Aerosol fluxing during metallization can solve this problem and neutralize the negative oxidative effect of interaction of the applied metal with air oxygen. This article discusses an effective method to improve physical and mechanical properties of an electrometallization coating using aerosol fluxing. The essence of this method is introduction of an aerosol together with compressed air into a torch of molten metal. This aerosol consists of an aqueous solution of the chemical inorganic materials. Such the aqueous solution is poured into a hydrodispergator, which is connected to the air channel of the metallizer. Aerosol fluxing makes it possible to deoxidize and ligate metal during electric arc metallization. As a result, the physical and mechanical properties of the metal increase. The paper considers the results of topographic studies of electrometallization coatings. Formed coatings have a structure with grain sizes from 200 to 2500 nm and also have pronounced and subtle grain boundaries. Aerosol fluxing with electric arc metallization forms a coating with finer-grained structure, which increases their strength. It is established that formed coatings have a finer-grained structure and increased strength when using aerosol fluxing during electric arc metallization. Metallographic studies showed that the thickness of the electrometallization coating varies from 2490 µm to 2586 µm. The use of aerosol fluxing during electric arc metallization does not significantly affect the coating thickness. The microhardness of electrometallization coatings was studied. This study showed that the use of aerosol flux consisting of Na₂CO₃, Na₃AlF₆, Na₂B₄O₇ during metallization increases microhardness of electrometallization coatings by 1.6 – 1.9 times.

The paper considers the study of the features of structure and phase transformations in high-strength, resistant to carbon dioxide corrosion, complex alloyed steels of martensitic, austenitic-martensitic and martensitic-ferritic classes with 13 – 17 % Cr. Influence of the alloying on crystallization and solid state phase transformations was revealed in the temperature range of hot deformation and heat treatment using thermodynamic modeling and experimental study. The effect of quenching temperature on the phase composition and microstructure was analyzed as a result of X-ray diffraction phase analysis, optical and transmission electron microscopy. It was found that increase of nickel content leads to growth of retained austenite fraction resulting in significant decrease of yield strength along with high tensile strength and elongation. To obtain predominantly martensitic microstructure in martensitic-austenitic steel, the multistage heat treatment is proposed including quenching, intermediate annealing for precipitation of dispersed carbides and tempering forming final mechanical properties. The composition of precipitated carbides was evaluated by X-ray microanalysis. The results of the tensile test for steels with martensitic and martensitic-ferritic microstructure showed that required strength grade (σ_0.65 ≥ 862 MPa; σ_в ≥ 931 MPa) was reached after heat treatment including quenching and tempering. Multistage heat treatment including quenching, intermediate annealing and final tempering was resulted in required strength properties of high-nickel martensitic-austenitic steel with 15 % Cr.

The article presents the results of analysis of evolution of the defective substructure of rail steel pearlite with lamellar morphology under deformation by uniaxial compression. The strain hardening of the studied steel under such deformation has a multistage character. Deformation of steel is accompanied by fragmentation of pearlite grains, which intensifies as the degree of deformation increases and reaches 0.4 of the studied foil volume at ε = 50 %. Fragments formed in ferrite plates are separated by low-angle boundaries. It was established that the average sizes of ferrite plate fragments decrease from 240 nm (ε = 15 %) to 200 nm (ε = 50 %) with an increase in the deformation degree. Fragmentation of cementite plates was revealed. It was found that the size of the fragments varies within 15 – 20 nm and weakly depends on the degree of steel deformation. Fracture of cementite lamellae, proceeding by their dissolution and cutting by mobile dislocations, was discovered. Carbon atoms that have passed from the crystal lattice of cementite to dislocations are carried out into the interlamellar space and form particles of tertiary cementite, the size of which is 2 – 4 nm. In the process of steel deformation, an inhomogeneous dislocation substructure is formed, which is due to the deceleration of dislocations by cementite particles. It was found that an increase in the deformation degree is accompanied by a decrease in the scalar and excess density of dislocations, which may be due to the escape of dislocations into low-angle boundaries, as well as their annihilation. It was established that the sources of internal stress fields are the interfaces between pearlite grains and colonies, cementite plates in pearlite grains, particles of the second phase located in the volume of ferrite plates.

The objective of the research was to identify transitional diffusion layers in the steel wire – brass coating system. Brass wire is used in the production of steel cord. Such wire made from steel 80 by dry drawing, two-stage deposition of brass coating (Cu + Zn) and subsequent diffusion annealing was used for this research. The chemical composition was studied using a TESCAN Vega3 SBH scanning electron microscope with an Oxford Instruments attachment for X-ray microanalysis (MRSA). To obtain maps of the elements distribution, the overlay of the received frames was used. The authors studied chemical composition of the brass coating of steel wire for steel cord by spectra; the copper concentration gradient was determined; iron content in the coating and copper content in the steel core were revealed. The presence of a transitional diffusion layer from a brass coating to a steel core on a wire for wet drawing with a diameter of 1.67 mm and 1.85 mm was determined in two parts with different thicknesses of a brass coating in opposite sections (maximum and minimum). A map of the elemental distribution of Fe, Cu and Zn is shown, as well as a general map of overlay of Fe, Cu and Zn content; graphs of the elements’ content for two studied cross-sections are presented. It was established that the transition diffusion layer has gradient transition in concentrations of Fe, Cu and Zn, which characterizes good connection of the brass coating with steel. Diffusion layer of a brass coating of a steel wire with a diameter of 0.30 mm, produced by wet drawing of a steel wire with a diameter of 1.67 mm, was studied. An image of the coating was obtained by overlaying frames. Thickness of the coating together with the diffusion layer was determined, the average value of which is 1.4 µm with an apparent coating thickness of 0.5 µm.

The authors investigated the intensity of heating of a moving strip of thermally thin metal on a finite length section by a system of attacking neutral gas jets. The article is devoted to solving the problem of creating a system for heating a strip of moving metal by attacking jets of neutral gas by estimating the intensity of heating a metal strip using mathematical modeling methods. The main options for heat treatment of sheet metal are named. The article describes the differential heat conduction problem and its subsequent simplification, considering the assumptions made to obtain an effective calculation algorithm; the empirical relations selected for calculating local and average values of heat transfer coefficients; and the basic parameters for variant calculations. For comparative modeling, a 20m-long section was considered, where a strip entering with a temperature of 500 °С is heated by neutral gas with temperature of 800 °С. The results of calculating the dependence of average cross-sectional temperature of the strip on its movement speed (in the range from 0.1 m/s to 2 m/s) at two values of the gas flow velocity (20 m/s and 40 m/s) are presented, on the basis of which the authors concluded that acceptable heating intensity is achieved only at low speeds of the strip, and the gas flow rate (in the considered range) is not a reserve for a significant increase in this intensity.