The usage of units with high reduction in the casting and rolling module would allow to improve the quality of the mill products due to intensive processing of bulk continuous cast slabs along the section and obtainment of homogeneous fi ne-grained metal structure, as well as to increase the cross-section of the continuous cast slab. The analysis of the formation causes of nonmetallic inclusions and liquates in the axial zone of thick-plate steel was carried out. The analysis of the deformation unevenness along the slab height during the reduction of large continuous cast slabs was performed at mill 5000 of JSC “Magnitogorsk Metallurgical Plant”. The design is described and the technological possibilities for defi nition of the cyclical deformation are presented for the preliminary deformation of continuous cast slabs. The technology is described and the parameters of the strikers for preliminary deformation of large continuous slabs were determined. The experimental study results of the deformation process of continuous cast slabs of steel 45 and steel 12Cr18Ni10Ti are given. The evaluation of the structure of continuous cast metal in the process of reduction of continuous cast billets at a cyclic deformation facility was carried out. The main parameters of the installation for preliminary deformation of large continuous cast slabs were determined. The technological possibilities of the installation for cyclic deformation were stated in terms of the essential improvement of the quality of sheet blanks. Based on the analysis of technological possibilities, it was proposed to use the cyclic deformation installation in the continuous casting line for preliminary reduction of large continuous cast slabs in order to fully adjust the speed of continuous casting and cyclic deformation and provision of the one-pass reduction with the degree of deformation 45 – 90 % to obtain a good casting structure along the slab cross-section. It was suggested, when using the installation in the line of a continuous casting machine, to perform reduction of continuous cast slabs using the heat of the cast metal, thereby substantially reducing the energy consumption in the technological process of producing the sheet blanks. The use of a cyclic deformation installation in the lines of thick-plate and wideband mills for preliminary deformation of heated slabs in one pass is proposed, which will improve the quality of sheet blanks and reduce the number of passes in rolling mills.

The high-energy impact on the material surface is used for the intensifi cation of surface diff usion saturation of steel. The article describes the process of microarc thermochemical treatment in which a steel product was immersed in a container fi lled with coal powder, and was heated by passing electric current. Microdischarges are formed in a powder environment. They are concentrated around the product and create a region of gas discharge. This leads to surface heating of the product and the surrounding powder environment. The pyrolysis of coal in a container formed a carbon-containing environment, which enables to carry out carburizing of steel. In addition, there is a possi bility of formation of carbide type surface due to the simultaneous diff usion of carbon and alloying element. Its source is a conductive coating containing the powder of diff usant. The authors have investigated the possibility of forming the coatings of carbide type by diff usion saturation of low carbon steel with vanadium. The cylindrical samples of steel 20 with a diameter of 12 mm and length 35 mm were used. The powder of low carbon ferrovanadium was used as the source of diff usant. The current density on the surface of the samples was 0.53 A/cm² , the temperature was increased from ambient to 1250 °С. To study the structure and phase composition of the diff usion layer optical microscopy, scanning electron microscope with energy dispersive microanalysis system, X-ray phase analysis, atomic force microscopy, microhardness analysis were used. After treatment for 3 min it was detected the formation of the diff usion layer with thickness of 170 – 180 μm. The basis of the diff usion layer is a solid solution of vanadium in α-iron with a vanadium concentration of 3 – 4 wt. % and the ratio of the number of atoms in the unit cell is 9:1, corresponding to α-Fe9 V with microhardness of 8.0 – 9.0 GPa. The layer base comprises the multiple nanoscale carbide inclusions, as well as carbides of the VC_0.863 type with the size up to 10 microns with vanadium concentration about 64 wt. % and microhardness of 21.65 – 25.75 GPa, undergoing the atomic ordering with the formation of the cubic V₈ C₇ superstructure.

The global volume of steel smelted in 2016 exceeded 1600 million tons, of which more than 1200 million tons of steel were smelted in the units of converter type. Depending on the number of technological factors, up to 25 kg of fi ne dust forms in the process of smelting of 1 ton of steel, which contains up to 65 % of iron in the form of oxides. The recycling organization of waste generated in metallurgical production makes it possible to reduce production costs by two to three times in comparison with the use of concentrates obtained from natural raw materials and minerals. In the context of solving the recycling problem of converter sludge, the method for conditioning high-moisture wastes was developed and improved, including their non-thermal adsorption dehydration and subsequent thermo-chemical agglomeration. The solid residue of brown coal pyrolysis is used as the adsorbent – a fi ne-grained brown coal semi-coke produced at the pilot plant of the open-pit mine Berezovsky-1. The obtained samples from brown coal char are of highly developed and porous structure and, accordingly, high adsorption capacity and energy properties. The granulo metric composition of the brown coal semi-coke is almost identical to the granulometric composition of the slurry. At the same time, the density of the brown coal semi-coke particles, even if the entire porous space is fi lled with adsorbed moisture, is more than 2.5 times lower than the density of the converter slurry particles. When mixing brown coal semi-coke and converter slurry, the former absorbs moisture, giving the mixture a high looseness, while at the same time the moisture adsorbed in the pores transforms into a bound state and becomes an active participant in oxidation-reduction processes. As a result of the experiments, the new material was obtained – “ferrocoke” containing up to 39 % of Fe_met and up to 49 % of C. The results obtained in the work made it possible to develop an effi cient technology for the utilization of converter sludge with production of a ferrocoke suitable for use in blast-furnaces and steelmaking plants as a coolant and reducing agent, without a complicated mechanical-thermal dehydration and briquetting with a binder.

The main scientific and practical results of improving the efficiency of the vertical collecting chambers for processing the dust of metallurgical industry are described through the development and implementation of a new generation of devices capable to improve environmental protection and working conditions, to reduce the loss of useful product. The authors have analyzed the technical and operational characteristics of the existing precipitators and means to reduce dust emissions into the atmosphere, and modern methods of dust cleaning. The theoretical basis of inertial dust collection was established and the parameters of additional precipitation surfaces were determined, providing output of the dust particles from turbulent laminar flow, to eliminate the secondary dust removal from the apparatus. The authors have described the scientific and technical basis for the selection and development of vertical construction of dust-collecting chamber with fiber curtains and a feasibility study on the replacement of the cyclone dust-collecting chamber. Theoretical study of the mechanism of dust deposition in the dust-collecting chambers and the results of laboratory studies of their efficiency with fiber curtains and inertial deposition of aerosol optic curtain are proposed. It is proved that the verticaldirectional but erasable flow interacting with the top of the disc-shaped partitions reflected flow is redirected in a horizontal direction along radii of chamber’s body at a decreasing rate as the distance from the center to the periphery in the range is from 0.35 to 0.035 m/s. When the performance of the aspiration unit is Q = 7500 m³ /h, diameter of inner curtains is d = 0.5 m, the chamber height H = 3.8 m and the filtration rate of gas through the curtain is 0.35 m/s, the filtration rate through the curtain with 5 m diameter is 0.035 m/ s. The authors have proposed new mechanism of dust deposition in the dust-collecting chamber and the influence of the electric charge of the particle and fiber on the effectiveness of dust deposition in the chamber. The design of a new vertical dust-collecting chamber is described with fibercurtains, in which the radial flow velocity decreases during the transition from one curtain to another, providing conditions for transition from inertial deposition of particles to the diffusion. It increases the collection efficiency of fi ne dust up to 95 % at initial airflow within the chamber of 0.35 m/s.

To produce articles of various confi guration from the metal sheet, a variety of devices are used. One of them is the sheet-bending rolls, which can be classifi ed according to several characteristics: number of rollers (two-, three- and four-rollers), type of the drive (mechanical, pneumatic, electromechanical and hydraulic) and by mutual arrangement of the rollers (symmetrical and asymmetrical). The three-roller sheet-bending rolls are used for the manufacturing of cylindrical, oval and conical shapes by bending of sheet’s metal. Using them, we produce pipes, gutters, air condition lines, shells, barrels and all kinds of covers. The working principle of the threeroller sheet-bending rolls is based on the oppositely directed rotation of the rollers, whereby the grip of the sheet material and bending by a given radius are taken place. To facilitate the sheet feeding and the extraction of products, bent into a closed circle, the three-roller sheet-bending rolls are equipped with the removable and adjustable to clamp front shaft. In the three-roller mill the upper roller’s diameter is about 1.5 times larger than the lower rollers’ diameter. In the process of forming, the rollers are making the reverse movement during which the upper roller may be raised and lowered to adjust the diameter of the moldable workpiece. In this shaping method the extreme small parts of the sheet remain fl at. This defect is eliminated by the bending of billet’s ends at the press or at the rolling mill. In this paper the mathematical method for determining the forces and bending moments at the cold bending of thick steel sheet on the three-roller sheet-bending rolls is proposed. The calculations allow us to determine the support reaction of rollers, residual stresses in the wall of the steel sheet, the proportion of plastic deformation on the sheet thickness and relative deformation of the longitudinal surface fi bers of the sheet under bending depending on the rollers’ radius, pitches bet ween the rollers, magnitude of the sheet reduction by the upper roller, the sheet thickness, as well as the elastic modulus, the yield stress and the hardening modulus of sheet’s steel. The research results can be used at the metallurgical and machine works in production of steel largediameter pipes for main pipelines.

The paper presents the theoretical and experimental studies to determine the optimal concentration of nanostructured powders in the shielding gas. The objective of this study is the development of a defi nition technique for optimal concentration of nanostructured powders in the shielding gas during welding by consumable electrode in the argon medium. Molybdenum nanopowder (NP Mo) was used to confi rm the calculations used in the experimental studies. The injection of the powder into the weld bath was carried out through the special device. The surfacing of samples was carried out in a pilot plant, which consisted of a welding head GSP-2 with the developed device, the power supply had rated current of 300 A. For surfacing of steel samples (austenitic steel with chemical composition: C – 0.12 %, Cr – 18 %, Ni – 10 %, Ti – 1 %) the welding wire with diameter of 1.2 mm was used (chemical composition: C – 0.12 %, Cr – 18 %, Ni – 9 %, Ti – 1 %,). To ensure the quality of the welded joint during welding, the dimension parameters of dendrites should tend to a minimum. A stable welding process is caused by the transition of electrode metal droplets from the end of the welding wire into the weld bath. Therefore, the volume of the electrode metal droplet should also tend to a minimum. Before the start of the optimization of nanostructured powders concentration in the shielding gas, the eff ect of welding mode parameters by consumable electrode in the argon medium on the microstructure of the weld metal was established. The results of the investigations have shown that the minimum grain size is observed at a current strength of 240 – 260 A and arc voltage of 28 – 30 V. In these modes, the studies were conducted to select the optimum concentration of nanostructured powders in the shielding gas. It was found that the optimum concentration of nanostructured powders-modifi ers in the shielding gas is 20 mg/m of the welded joint. It was established that the use of diff erent concentrations of nanostructured powders in the shielding gas makes it possible to obtain a diff erent microstructure of the weld metal. The most lightly branched dendrites and the equilibrium structure according to the dendrites size are achieved at a concentration of nanostructured powder in the shielding gas of 20 mg/m of the weld. When adding nanostructured powders-modifi ers to a liquid weld bath, the mechanical properties of the welded joints increase as compared to the welding process, without the addition of a powder-modifi er at +20 °C by 7.5 %, at +500 °C by 6.5 %.

The study of structural transformations in nanocrystalline nickel, containing <111> and <100> edge boundaries, under the eff ect of deformation was carried out using the method of molecular dynamics. Nanocrystalline nickel was created in the model by crystallization from a liquid state of the computational block in a plate shape of 1.5 – 2.0 nm thickness, containing specifi cally introduced crystal seeds – cylindrical crystalline areas with the fi xed motionless atoms. When creating the computational block, the cylindrical areas with a crystalline structure were rotated to random or predetermined angles around the central axis of cylinders. It was done so that the fi nal crystal grains after crystallization had edge boundaries between each other. Interactions of nickel atoms were described with the help of many-body potential of CleriRosato, constructed in the tight-binding model. Deformation of the compression or tension was set by changing the interatomic distances along a given axis. The main attention was paid to studying the mechanism of plastic deformation with the participation of grain boundaries and triple junctions. The following questions considered: what is the preferably initiator of the plastic shears: surface or boundary; whether there are manifestations of self-organization in this case; whether the dislocations are generated or mechanism of plastic deformation in the case of nanocrystalline structure is mainly due to grain boundary sliding. In the present study, as a result of the computer simulation it was found that the plastic deformation with the grain size of several nm is performed mainly by the grain boundary sliding without the formation of dislocations and intragrain slip. Herewith the grain boundary sliding in some cases accompanies the grain rotation. Displacements of atoms in the plastic deformation process in these materials were formed primarily from free surfaces: at the tension atomic displacements usually were directed from the surface into the polycrystal, at compression, conversely, toward the surface. As a result of the deformation the recrystallization process proceeded in the simulated nanocrystalline Ni more intensively, defects and excess free volume intensively migrated to the interfaces (grain boundaries and free surfaces).

The nanohardness, Young elastic modulus and defect substructure of the layer surfaced on the low carbon martensite Hardox 450 steel by the high carbon power wires with diameter of 1.6 mm of different chemical composition (containing such elements as V, Cr, Nb, W, Mn, Si, Ni, B) and two times additionally irradiated by the pulse electron beam were studied for the purpose of substantiated selection of coating material corresponding to the product operation conditions and the modes of subsequent electron beam treatment. The formation of the fused layer on the steel surface was carried out in the shielding gas medium containing 98 % Ar, 2 % CO₂ , with a welding current of 250 – 300 A and a voltage on the arc of 30 – 35 V. Modification of the deposited layer was carried out by irradiating the surface of the deposited layer by a high-intensity electron beam in the mode of melting and high-speed crystallization. The load on the inductor was 50 mN. Determination of the nanohardness and Young elastic modulus was carried out at 30 arbitrarily chosen points of the modified surface. The defect structure of the surface modified by of an electron beam of the surfacing was studied by scanning electron microscopy. A multiple increase in nanohardness and Young elastic modulus of the welded layer was revealed during electron-beam treatment according to the base material. It was found that the maximum hardening effect is observed at surfacing by a flux-cored wire containing 4.5 % of boron. It is shown that on the weld deposit surface formed by the wire with 4.5% of boron and additionally irradiated with an intense pulsed electron beam, the formation of a microcrack system on the surface of irradiation was revealed. Investigations of weld deposits, formed by non-boron-containing powder wires, have shown the absence of microcracks on the modified surface after pulsed electron beam treatment. The increase in the strength properties of the deposited layer modified by the electron beam is due to the formation of structures which crystallite sizes vary from tenths of a micrometer to one micrometer and contain second phases (borides, carbides, carbborides). A significant spread of the values of the nanohardness and the Young elastic modulus was established, which was apparently due to the inhomogeneous distribution of the strengthening phases.

The analysis of the research results of temperature dependences of the kinematic viscosity, electrical resistivity, surface tension and density of liquid steels and alloys during heating and the subsequent cooling was performed. The identifi ed characteristics formed the basis for systematization of physical properties polytherms of steels and alloys. It was established that the changes occur in the melt structure during heating up to certain critical temperatures. As a result, the cooling polytherms acquire a diff erent view, more close to equilibrium classical patterns and do not coincide with heating polytherms. The branching of the temperature dependences of the physical properties or hysteresis of polytherms is irreversible only when heating up to a temperature not lower than the critical ones. If these conditions are not met the partial or full return to the primary structure of melt can occur and it has an impact on the value of the polytherms hysteresis. Therefore, the hysteresis value, along with the data on the properties, is a qualitative characteristic of the melt structure and its deviations from the equilibrium and micro homogeneous state. The uniformity of distribution of alloying elements atoms into micro groups or clusters indicates the equilibrium of the structure and uniformity of clusters distribution, diff erent in structure in the melt volume, refl ects its structural micro-homogeneity. In the process of studying the properties of multicomponent metal materials it was found that after melting the change of melt properties at isothermal holding is a typical pattern of damped oscillations. With the increase of temperature the damping mode approaches the aperiodic one, and the relaxation time decreases. The processes responsible for kinetics of isothermal change in the melt properties occur at the micro level. Non-equilibrium industrial metal typically contains inclusions from the initial materials in the form of undissolved particles of graphite in the cast iron, association and aggregation of carbides, nitrides, etc. Bringing such melt into equilibrium state requires a lot of time, normally much more than for the diff usion transfer of atoms within the disbalanced zones. The more complex is the chemical and structural interactions of solid metal, the greater is the separation between the equilibrium and the obtained melt. In such system the new correlations are formed and broken most intensely. In this case the cooperative processes of interaction of new spatial and temporal structures with inherited from the initial materials take place occur, which is refl ected by oscillating dependences of the properties of metal melts. The information about the state of the melt prior to solidifi cation enables a scientifi c foundation for temperature and time regimes of smelting of steel and alloys. Such melt preparation aff ects its capacity for supercooling, the crystallization rate and the formation of eutectic reinforcing phases, elements segregation, dendrites structure and zonal structure of castings, and in general – the quality and effi ciency of steel production.

A new composition of the powder wires based on the C – Si – Mn – Mo – V – B and C – Si – Mn – Cr – Mo – V doping systems represented by steels 40GMFR and 40Kh3G2MF was developed. The influence of alloying elements in the composition of C – Si – Mn – Mo – V – B and C – Si – Mn – Cr – Mo – V powder wires on the size of the martensite needles was studied, as well as the primary austenite grain size and the contamination of the weld layer with non-metallic inclusions. The infl uence of the structure on the strength and durability of the deposited metal was defi ned. It is shown that an increase in the content of carbon and alloying elements, in particular chromium, in the composition of the welded steel contributes to the formation of a structure with a medium-carbon fi ne-grained martensite and a small volume fraction of δ-ferrite. It provides reduction in size of the primary austenite grain and decrease in the contamination degree of the deposited layer with non-metallic inclusions. The established improvement in the structure aff ects the hardness increase up to 22 % and the decrease in the abrasion rate of the deposited layer up to 34 %. The chemical composition of samples welded with a fl ux-cored wire of C – Si – Mn – Mo – V – B system is characterized by a lower content of carbon and alloying elements compared to a 40Kh3G2MF steel, which causes the formation of low-carbon martensite in the structure after surfacing. It was established that a signifi cant increase in the content of carbon, manganese, chromium, vanadium and molybdenum in 40GMFR welded steel provides a structure with fine needle and medium needle martensite, reduces the size of the primary austenite grain and the contamination level of the deposited layer with non-metallic inclusions, in particular, non-deformed silicates. Changes in the micro structure are accompanied by an increase in hardness up to 16 % and a decrease in the attrition rate of the deposited layer up to 20 %. As a result of a comparative analysis of the two studied systems of powdered wires, it was found that it is more eff ective to use C – Si – Mn – Cr – Mo – V wire for surfacing mining equipment, since the content and ratio of alloying elements in steel of type 40Kh3G2MF contributes to obtaining a dispersed martensitic structure with an insignifi cant volume fraction of δ-ferrite, which provides high hardness and wear-resistance of the deposited layer.

The article considers a promising combined method for increasing the production effi ciency of the section rolling profi les – rollingdivision with the use of non-powered dividing tool, the experience in the use of which in the conditions of production has shown high effi - ciency of this direction in terms of reducing the cost of the fi nished product. The dependences, which allow to defi ne the frequency separation, and high-speed conditions when deciding industrial introduction of process technology of rolling-separation on current continuous small-section mill 250. The existing experience of implementing the rolling process-separation model of continuous small-grade mill 250 has been reviewed, which allowed to reveal the peculiarities in the distribution coeffi cients of drawing and changing speed conditions for groups of stands. It was found that on the basis of capacity of rolling equipment on the mill, it is advisable to carry out the longitudinal separation of the workpiece into two bands in the fi nishing group of stands, and changes in the total coeffi cients of drawing and rolling speed on rolling groups were also identifi ed. The article presents data on changes in the machine time for reinforcing the profi le no. 10, no. 12, no. 14 in connection with the development of technology in the process of rolling-division, which in turn contributed to increasing eff ectivelySTI production of existing continuous small-section mill. Proven in the industry values of the total coeffi cients of drawing and rolling speed on rolling groups can be determined from the shown illustrations. In addition, the study process was carried out for experimental – industrial rolling of rebar no. 8 under conditions of continuous light section mill 250-1 of the rolling shop of JSC “EVRAZ ZSMK”. The authors have compared the coeffi cients of drawing and rolling speed in the production of rebar no. 8 on the continuous wire mill 250 and a continuous small-section mill 250 from the same piece – square 100 mm. The results are provided in the illustration, which shows that the use of the rolling process-separation allows to use four stands less than at the rod mill at production of rebar no. 8 at a small-section mill.

Development of mathematical models of coal-ore pellets burning process was executed on the conveyor machine. The problems of heat transfer between gas and material in the transversally blown dense laye r are considered. The description is given for the following aspects: the phenomena of drying and cooling of materials (inclu ding by air-and-water mixture), oxidation processes of ore constituents of pellets, dissociation of limestone and burning of fuel constituents of material. Equalizations of the engineering mathematical models of iron oxides recovery and burning of fuel granules and of heating of machine’s fi re grate (carts) are resulted. When calculating the development of physicochemical transformations in the volume of the pellet, it was assumed that any chemical reaction from the surface of the granules of a particular component proceeds over the entire inner and outer surfaces of the pellet, and the process potential (the diff erence in the concentration of gaseous reactant) is a function of the pellet’s radius, the diff usion coeffi cient of reagent in micropores of the pellet. At the same time, the response in the individual pellet is frontal, and the completion degree of the process can be expressed through the radii of unreacted pellet volumes. Among all physicochemical phenomena accompanying the process of calcination of coal-ore pellets, this mathematical model directly takes into account only the main ones, which are refl ected in the material balance and can be verifi ed experimentally. Finite-diff erence approximation of equations of the mathematical model together with the expressions for calculating the thermophysical characteristics of heat carriers, heat and mass transfer coeffi cients, thermochemical and kinetic constants, etc. have formed the basis of a numerical model of a conveyor burning machine that produces metallized pellets. The implementation of this model in the particular case is presented in the article.