The movement specifics of a germ with complex shape on the pelletizing disk in production of iron-ore pellets are considered. As a result of the analysis of the forces acting on the cubic germ during its roll on the charge scull (CS) in the conditions of plastic deformation, a mathematical model was build that allows the optimal parameters of the pelletizer to be determined for the production of pellets based on the technology of a forced germ formation. Two particular cases of germ stability on the pelletizer CS and the conditions for the over-coming of the stability associated with the formation of a roll are considered. The germ stability, or conversely, its roll is determined by the horizontal position of its mass center relative to the support edge located across the probable direction of the roll. If the line of the acting force (gravity force) moves behind the support edge and the reference plane, a force moment will be generated which will lead the germ out of the stability state and form a germ roll. The first special case of germ stability on the inclined plane is the absence of a roll on the CS with a minimum value of the centrifugal force corresponding to the location of the germ in the central areas of the pelletizing zone or to operation of a working element with a low rotation speed (n  <  3  rpm) . A more general case of the transition of the germ from the state of stability into the roll regime on the inclined plane of CS is the work of the pelletizer when centrifugal force is relatively high (n  >  3  rpm) and location of the germ in peripheral areas of the working zone of the pelletizer. For these cases the conditions for germs roll on the CS in the pelletizer working zone and correcting measures in the conditions of plastic deformation during the corners and edges crushing are formulated. The features of the germ movement in the working zone of the pelletizing disk are shown. The conditions for correcting the regime of forced germ formation are provided, and the measures are indicated for the purposeful impact on the crushing factor of a germ. It was established that for the organization of the regime of a germ roll with complex shape the angle of disk inclination to the horizon should be set depending on the frequency of its rotation and the crushing factor of germs.

Nanopowders (NP) based on cobalt have significant prospects for use in various fields of science, engineering, industry and medicine.In this work the authors have studied the kinetics of the production of metallic cobalt nanopowder by hydrogen reduction of oxide material Co₃O₄ in an electromagnetic field, and with an energy-mechanical processing (EMP) in eddy layer created by ferromagnetic bodies subjected to such field.Cobalt oxide Co₃O₄ NP was obtained by thermal decomposition of the hydroxide compound Co(OH)₂ chemical-precipitated from 10  % aqueous solutions of nitrate cobalt Co(NO₃)₂ and sodiumhydroxide NaOH under the conditions of pH  =  9 and t  =  20  °C. The production of metallic cobalt nanoparticles by the hydrogen reduction of Co₃O₄ NP was carried out on the apparatus of eddy layer (AED) of UAP-3 model modified with an internal heating furnace and a flow reactor. The amplitude value of induction of magnetic field inside the reactor was 0.16  T. The experimental temperatures of the reduction process were chosen based on the result of a thermogravimetric analysis (TGA) of the initial cobalt hydroxide sample. The kinetic parameters of hydrogen reduction processes under linear heating and in isothermal conditions were calculated using the Freeman-Carroll and McKewan models, respectively. The authors have found a decrease in the rate of obtaining Co nanopowder in the electromagnetic field (up to 14  % at 250  °C) due to the decrease in the adsorption ability of hydrogen atoms on the surface of the formed metallic nanoparticles. EMP in the eddy layer leads to an increase in the reduction rate by 4  –  5 times due to the effect of mechanical activation of the material. The properties of the initial material and the obtained products were investigated using the methods of thermogravimetry, X-ray diffractometry, electron microscopy and measurement of the specific surface area by low-temperature nitrogen adsorption. It was shown that reduction of the samples in the electromagnetic field facilitate the formation of more finer-dispersed Co nanoparticles, than in the case without the field. The EMP in the eddy layer leads to the aggregation of the formed metallic nanoparticles and the formation of granules of micron size.

The work focuses on modeling of processes occurring in the mold with a new patented cooling system in continuous casting machine, in particular, at temperature drop in metal of the stock and in the wall along the height of the mold, on which quality of the resulting billet depends. In the review, works are referred in which slag- forming mixtures (SFM) are investigated that affect heat flow from stock metal to the mold. Foreign authors put emphasis on “soft” cooling of the mold by selection of the SFM. Improvement in process of stock metal cooling in the mold is primarily aimed at improving quality of slab surface, increasing resistance of the mold and increasing productivity of machine, which, according to several authors, can be achieved by mathematical modeling of the process. The problem of mold cooling depends directly on convective motion of liquid steel in the mold, which is considered in a number of works of foreign authors. Use of the principle of heat pipes operation in cooling system of the machine mold, in particular, using porous material with water and air operating medium, as well as the question of liquid droplets evaporation on nanostructured super-hydrophilic surfaces, draws attention of researchers. Cooling of the mold at metal casting speeds of more than 7  m/min, accompanied by an increase in heat flux density, is an urgent task and is considered by a number of authors. Interrelation of the main parameters of the process is determined using Rayleigh dimension theory. Temperature gradient in metal of the mold wall is determined as the main parameter, depending on casting speed (time of stock metal forming in the mold), properties of poured metal (heat capacity, heat conductivity), thermal conductivity of the mold wall, and temperature drop in molded metal. Exponents for similarity criteria are determined taking into account available experimental data on dependence of heat flux density on accepted speed of steel casting, steel parameters. The ratio ∆t_c  /t_c (where ∆t_c is an average temperature difference across the wall thickness, tc is an average value of a wall temperature) for the mold with the existing and the new (patented) cooling system allows us to determine temperature difference in metal of the billet, which in two compared cooling systems of the mold comprises ∆t_м1  =  450  °С and ∆t_м2  =  231  °С, and the ratio – ∆t_м1/Δt_{м 2} is 1,95  times. Decrease in metal temperature drop ∆t_м2 indicates more “soft” cooling of the mold with a new cooling system.

The results of barium-strontium carbonatite application in metallurgy for modifying and refining iron-carbon alloys are generalized. It  is proposed to use bariumstrontium carbonate in welding fluxes manufacturing. BSK-2 barium-strontium modifier produced according to TU1717-001-75073896-2005 by “NPK Metalltekhnoprom” LLC of the following chemical composition: 13.0–19.0%ВаО, 3.5 – 7.5 % SrO, 17.5– 25.5 %СаО, 19.8– 29.8 % SiO₂, 0.7– 1.1 %MgO, 2.5– 3.5 % K₂О, 1.0– 2.0 %  Na₂O, 1.5– 6.5 % Fe₂O₃, 0 – 0.4 % MnO, 1.9–3.9% Аl₂O₃, 0.7–1.1% TiO₂,16.0 -20.0% CO₂ was applied. Technology of manufacturing a flux agent containing 70% of barium-strontium carbonatite and 30% of liquidglass is proposed. Several compositions of welding fluxes based on silicomanganese slag were tested. Flux agent was added in an amount of 1, 3 and 5%. Technological specifications of welding under investigated compositions of welding fluxes are determined. X-ray spectral analysis of chemical composition of the investigated fluxes, slag crusts and weld metal were carried out, as well as metallographic investigations of welded joints. Principle possibility of barium-strontium carbonatite application as refining and gas-protective additive for welding fluxes is shown. Application­ of barium-strontium carbonatite provides reduction of weld metal conta­ mination with nonmetallic inclusions: non-deflecting silicates, 1D oxides and brittle silicates, and also increase desulfurizing ability of welding fluxes. Introduction of barium-strontium carbonatite into fluxbased on silicic and manganese slag in an amount of up to 5% provides ferrite-pearlitic structure of the weld metal of Widmanstatten orientation, while the grain size slightly reduces from no.4 to no.4, no.5.

The article considers the question of nucleation sites during phase transitions, which, even for thoroughly studied martensitic transformations, remains an essential one. Generality of shear nucleation and nucleation site for diffusion (normal) and martensitic transformations is discussed. Specific aspects of nucleation have been studied through surface relief observation of 30KhGSA and U12 steel and technical iron by means of high-temperature metallography, and also by microstructural study of the initial stages of phase transformations of porous sintered steels with carbon content of 0.40 and 1.57  %. Pictures of austenite origin from low-angle and large-angle boundaries are presented, which testify to shear mechanism of its formation. Numerous acts of ferrite nucleation at γ-phase grain boundary are shown for both slow and fast cooling, which forms the morphology of the acicolar (Widemanstatten) ferrite. In 30KhGSA and U12 steels martensite is formed along the grain boundaries, although other nucleation areas, for example, such as packing defects, inclusions, special dislocation configurations, are not excluded, but they are not preferential. In samples­ of porous steel, predominant growth of twin crystals of martensite from pores takes place. The obtained experimental data on embryos of austenite and ferrite indicate a shear mechanism of nucleation at the initial stage of diffusion transformations, which subsequently is replaced by normal growth mechanism with formation of equiaxed grains. It is concluded that, despite the differences in phases nucleation nature and conditions, acts of nucleation in all cases occur in the same way, and the differences­ begin at the stage of growth. It is shown that shear nucleation can start from grain, subgrains boundaries and also from free surfaces (for example,­ pores in sintered steel). Nucleation in these places is facilitated by relaxation of transformation stresses and liberated part of the grain-bound-ary energy. Revealed rhomboidal morphology of martensitic­ crystals formed on pores can be explained by the fact that nucleation from free surface occurring under conditions of minimal influence of elastic fields of the surrounding matrix encourages implementation of general regularities of martensitic crystals growth.

Currently, there is a difficult situation in the production of ferronickel  –  the reserves of rich nickel ores end, and well-developed and established classical production schemes do not provide economically efficient processing of poor oxidized nickel ores. It seems promising to use for this raw material new highly efficient and economical processes for the production of primary metal using orecoal briquettes, for example, the ITmk3 process or the smelting process in an oxygen reactor. To study the applicability of the solid-liquid-phase carbothermic reduction process for ore-coal briquettes for poor oxidized nickel ore, the conditions were used most simulating industrial conditions-the discharge of a briquette of industrial size (diameter 24  mm, height 30 – 35  mm, weight 20  –  30 g) in conditions of the furnace hot zone with a temperature of 1500 °С. The briquette surface temperature was measured with the «Pyrovision  M9000» thermal imager, and the gas phase analysis was performed using a «Gasochrom-3101» chromatog­ raph. It has been experimentally established that the temperature of the briquette varies according to the same logarithmic law. Under the assumed assumption – formation as a result of reduction in the gas phase of carbon monoxide alone and taking into account a logarithmic increase in the heating rate of the sample, the experimental procedure allows to determine the rate and degree of reduction as a function of time, the total reduction time, compositions of the produced metal and slag, order of the reaction, the activation energy and limiting stage of the process. Experiments with various types of reductant and different briquette compositions at a temperature of 1500 °С have been carried out. It is shown that the process proceeds in a mixed mode with simultaneous control by internal mass transfer and chemical reaction. The optimal conditions for the solid-liquid-phase carbothermic reduction of oxidized nickel ore are determined: the type of reducing agent is semi-coke, the concentration of the reducing agent in the briquette is 5  %; fractions of components are less than 1  mm; process temperature is 1500 °С; the recovery time is 12  minutes. By varying the content of reducing agent in the briquette, it is possible to obtain ferronickel with a nickel concentration of 5 % to 22 %.

The article considers the process of elastic-plastic transition in welded samples from low-carbon steel. Two methods of manualarc welding with a consumable electrode are used: traditional fixed arc and pulse welding with controlled heat input. It is shown that both methods are identical with respect to the obtained structural characteristics and mechanical properties. In both cases, a stretched elastic-plastic transition is observed by the nucleation and propagation of the Luders bands. However, depending on the welding method, it is realized in different scenarios. When using traditional welding with a stationary arc in a loaded sample, the Luders band nucleus is formed in the weld metal first in the form of diffuse deformation localization regions that fill the seam and transfer it to a plastically deformed state. Movable fronts of the band are finally formed in the heat-affected zones and pass into the base metal. The velocities of fronts and their morphology are identical to those of fronts in similar objects of similar steel. In the case of pulsed arc welding, the nucleation of the Luders bands occurs at a distance from the weld seam at the clamps of the loading device. Up to the heat-affected zones, the morphology and the velocity of the fronts correspond to the data for the parent metal. At the fusion boundary, the front stops and forms the nucleus of a new band that sprouts into the weld metal. This new band first transforms the weld metal into a deformed state, and then creates a movable front in the opposite heat-affected zone. The velocities of the fronts in the deposited and base metals differ by an order of magnitude. The welded seam determines the process of nucleation of the Luders band. The explanation of different scenarios of elastic-plastic transition is offered depending on the welding method. When using the traditional method of welding with a stationary arc in heat affected zones, the local long-range stresses are much higher than in the base metal, so here, as a relaxation process, the band originates. In the case of pulsed arc welding, these stresses are higher in the base metal, where the Luders bands originate. The obtained data can be used to justify the parameters of the heat-and-power equipment test.

In this paper, the authors propose a model of electroerosion destruction of composite electroexplosive coatings of W – Cu, Mo – Cu, W – Cu – Cu, Mo – Cu – Cu, Ti – B – Cu, and TiB₂ – Cu systems underspark erosion that occurs when electrical contacts are opened. The model is associated with the evaporation of electrodes under the influence of heat flow, which arises from sparking when electrical contacts are opened. In constructing this model, the resistance of electrical contacts during the tests was in the range from 40 to 50  μΩ. The model was constructed in the framework of the problem of heating a half-space by a surface normal pulsed heat source uniformly distributed over an area of a certain radius and with certain duration of action. Distribution of the pulse energy in time was approximated by a rectangular pulse. The heat equation was solved in a cylindrical coordinate system for a plane instantaneous source with allowance for a finite time of the pulse. The vapor pressure of the metal was determined from the surface temperature. The calculations were carried out at a voltage of 380  V, a current of 3  A, a spark discharge time of 150  μs and a radius of the contact spot of a spark discharge with a surface of 152  μm. As a result, there were determined: the surface temperature of electrodes from pure metal, the surface temperature of electrodes from composite coatings, the depth of the evaporation layer of electrodes from pure materials, the loss of mass of the composite coating after a single discharge pulse, the relative change in the volumetric electroerosion resistance of electrodes from pure materials, durability of electrodes from pure materials, relative change in volumetric erosion resistance of electroexplosive composite coatings and the relative change in mass spark resistance of electroexplosive composite coatings. The partial composition of the elements­ included in the composite coating was calculated. The obtained results are in good agreement with the experimental results, especially in the W – C – Cu, Mo – C – Cu and Ti – B – Cu ternary systems. Comparison with data from the literature has a fairly good degree of correlation. Deviations for the binary W – Cu, Mo – Cu systems have causes in the model approximations.

Evolution of carbide phase in surface layers of volume (passed gross tonnage 500 and 100  million tons) and differentially hardened rails (passed tonnage – 691.8  million  tons) to a depth of 10  mm along the central axis and along the rail head fillet was studied by means of transmission electron diffraction microscopy. The grains of lamellar perlite, ferrite-carbide mixture, structurally free ferrite are analyzed. The flow of two complementary mechanisms of transformation of carbide phase of steel in the surface layers during the rails operation was identified: mechanism of cutting cementite particles and their subsequent­ transfer into the ferrite grains or plates volume (in perlite structure); mechanism of cutting and following dissolution of cementite particles, transition of carbon atoms to dislocations (into the Cottrell­ clouds and the dislocation centers), transfer of carbon atoms within dislocations to the volume of grains (or plates) of ferrite, with the following repeated formation of nanoscale cementite particles. A  fragmented dislocation substructure is formed instead of former plates. Fragments boundaries decorate places where cementite-α phase interphase boundaries used to be. The main reason for dissolution of cementite is that it is energetically more preferable for carbon atoms to be on dislocation centers and on subboundaries than in cementite lattice. Binding energy of carbon atom-dislocation is 0.6  eV, for carbon atom-subboundary bond it is 0.8  eV, while in cementite it is held by 0.4  eV. Formation of elastoplastic stress fields is detected, concentrators of which are intra and interphase boundaries between grains of ferrite and perlite, cementite and ferrite plates of perlite colonies, particles of globular cementite and ferrite. The main sources of curvaturetorsion of metal lattice of rails metal are intraand interphase bounda­ries­ of grain separation of ferrite and perlite, cementite and ferrite plates of perlite colonies, particles of globular cementite and ferrite. Approaching to the rolling surface, number of stress concentrators and amplitude of internal fields of longrange stress are increasing.

Based on dynamic model of multi-motor drive of continuous casting machine (CCM) coolers, mathematical model is formed andevaluation of low- frequency dynamic processes occurring in the drive is performed. Model of the coolers drive is an eight-mass dynamic system with elastic connections between masses. Description of links takes into account presence of gaps and damping properties in them. Active load in dynamic model is described by mechanical characteristic of hydraulic drive. The cooler moving beams and cooling metal mass are regarded as reactive loads. Motion of all masses of the model is described through the system of second-order differential equations. Integration of differential equations was carried out by Runge-Kutta method. To analyze influence of various­ factors on loads that arise in cooler drive, a software program was written. Evaluation of dynamic processes in the CCM cooler drive shows that dynamic component of load in the elements of machine for vertical displacement of mobile beams is of a significant value. Dynamic response factor K_d in the drive elements reaches 2.2  –  2.3. Analysis of the factors influencing dynamic processes in the cooler drive reveals that the optimum ratio of masses of metal located in cooler and moving beams of the cooler is close to 1.6  –  1.7. The minimum dynamic coefficient is close to 1.5. The nature of change in drive dynamics due to viscosity of working fluid of hydraulic drive is smoothly decreasing linear dependence with a minimum corresponding to fluid viscosity value of 4·10–5   m2/s. Speed of vertical displacement of the moving beams of the coolers also affects dynamic processes that arise in their drive. At the same time, the dynamic response factor is higher with the higher speed. Within the limits of change in speed of movement of the moving beams of the cooler referred to in the paper, K_d varies from 2 to 2.2. Dynamic model of multi-motor hydraulic drive of cooler of a walking-type used in the work makes it possible to analyze low-frequency dynamic processes occurring in hydraulic drive. As a result, it be comes possible to identify degree of influence of various design and power conditions of operation of hydraulic drive on low-frequency oscillations in it and, to develop optimal design solutions in terms of its operability using calculating tool.

The issues of using highly efficient technologies in the production of pipes on the piercing press of a pipe press installation are considered. The existing basic and perspective directions of intensification of deformation modes in the processes of metal forming using active controlled high-frequency vibrations are analyzed. It was established that, due to insufficient study, vibration processes do not find wide application in the production of seamless pipes. By analyzing and synthesizing a number of known fundamental studies, it has been shown that favorable conditions for metal deformation can be achieved by using high-frequency vibrations. It was revealed that the operation of the pipe billet piercing on the piercing press is accompanied by considerable losses to overcome the forces of technological resistance, characteristic for the process of deformations unevenness throughout the volume of the processed metal. Some previously unknown phenomena that arise during the implementation of existing technologies for pipe billets piercing have been established, which required the creation of new mathematical models of such processes that adequately reflect the conditions of the process of piercing or expanding the billets on modern piercing presses. A mathematical model of the dynamic wave processes arising in the processed metal is made. For the quasistationary process of pipe billet piercing differential equations of wave formation are obtained at the corresponding boundaries of the zones of the deformation center, characteristic for the plastic zone and the zone with cracking in the pierced metal. The parameters of the wave propagation boundary in the pierced pipe billet on the conjugate fronts of the plastic zone with the zone of crack formation are determined. It was established that deformations and stresses in the pierced metal depend on the rate of expansion of characteristic waves at the interface of contact with technological tools. A highly effective innovative technology of vibration piercing of a pipe billet on a piercing press of a pipe-rolling mill is substantiated. The features of realizing the technology of active controlled vibration piercing of the pipe billet on the piercing press of a pipe-rolling mill are determined. It is shown that the use of high-frequency oscillations on the press contributes to a significant increase in the efficiency of the technological process of piercing or expansion of pipe billets. The choice of rational parameters of high-frequency vibrators (amplitude-frequency characteristics), built into the system, resulted in a noticeable decrease in the energy-strength parameters du­ ring the piercing of the pipe billet and a significant improvement in the quality of the produced sleeves.

Explicit algorithmic normative model of technological line operation was developed, technically possible and normative values of work cycles and line productivity were calculated. Normative digital prototype of operation of coppering unit was designed, taking into account a number of lines, a number of wire “threads” used on each of them for calculation of multivariate technically possible and normative values of the system’s productivity.