Known technologies of diffusion molybdenum saturation of steel products are characterized by a number of disadvantages. The article presents the investigations of the diffusion saturation process of molybdenum by microarc chemical-thermal treatment technology. The steel sample has been dipped into the coal powder and heated by electric current. Ammonium molybdate has been used as a source of diffusant. The standard change of Gibbs energy has been calculated to identify the most probable chemical reactions. The authors have defined temperature intervals of reduction reactions of molybdenum trioxide with the formation of molybdenum dioxide and atomic molyb denum. An experimental verification of the results has been made. Carbide coating has been received with the thickness of 80 – 150 microns with a microhardness of 13.5 to 15.0 GPA.

The discrete analog of diff erential equation of heat conduction allowing applying irregular computational net for the mathematical modeling of continuous casting was proposed. This method of meshing allows taking into account the distribution of temperature gradients in the model. It improves accuracy of the approximation and adequacy of the computation results. The mathematical model of crystallization and shrinkage of slab in CCM mold was developed. Application of irre gular computational net allowed using the elements of size of 1 – 2 mm in modeling. The researches of slab cross-section profi le distortion under the influence of the mold were conducted on the basis of this model. Calculation of the geometrical profi le allows to specify the conditions of the thermal and mechanical interaction of the solidified shell with the mold walls and to solve the task of determination of optimal mold taper of CCM, ensuring reduction in number of slabs aff ected by surface and subsurface cracks.

The problem of stationary heat exchange in the blast furnace smelting zone irrigated with melt, considering features of process of a fi ltration of pig-iron and slag through coke nozzle is formulated. It is shown, that in this zone there is a simultaneous heating by gas of streams of coke, pig-iron and slag, each of which is in a heat exchange condition among themselves. The processes of mutual heat exchange are carried out as convection and radiation. Convection provides heat interchange among gas and all the heated up materials, and also between slag and coke as slag fl owing down on coke partially coats its surface. Radiant heat exchange develops between coke, pig-iron and slag. Its intensity increases with the growth of temperature of heated up materials. It is fi xed, that mutual heat exchange among streams of coke, pig-iron and slag in an irrigated zone of a blast furnace makes considerable impact on formation of a temperature fi eld in this zone. The knowledge of thermal eff ects distribution of chemical reactions of direct restoration of iron, silicium and manganese are necessary for calculation of heat interchange in the fi eld of bosh and a blast-furnace well on height of an irrigated zone and a fraction of a surface of the coke, coated with slag.

The article is devoted to the development of the analytical design procedure of solidifi cation and cooling of large-tonnage bloom ingot. As the analysis result of the reference model and the received solutions, a universal way has been worked out to calculate the mode of solidifi cation and cooling of ingot in the industrial conditions from the casting to charging into the cell of soaking-pit furnace. The satisfactory matching with the results of the industrial experiment has been shown when using the analytical nomogram-graphical method of the calculation. The way of calculation allows defi ning the total time of ingot solidifi cation and the surface temperature in the process of solidifi cation, condition of crystallization front in a set moment of time, duration of cooling of the overheated melt and other parameters. When using the analytical and nomogram-graphical method of the calculation, the preparation technology of industrial bloom ingot to the heat has been improved, as well as corrected the operating heating mode of ingot with the increased heat content (liquid kernel), which has been tested and implemented in industrial conditions. Realization of the mode has shown the heating time reduction of ingots and the decrease of fuel rate.

The article gives the thermodynamic assessment of the probability of hydrogen removal processes from the welded metal during welding under fl uoride fl ux in standard states at the temperature range 1700 – 2200 K. Na3AlF6 ж , ЅіО2 ж , SiF4 г , NaAlO2 тв , Na2SiO3 ж , CaF2 ж , CaSiO3 тв , Н2 г , SiF2 г , HFг , О2 г , SiFг , Ng have been selected as the standard states for substances reagents. As the result of calculation of standard Gibbs energy and the equilibrium constants of the reactions, it has been determined that the reactions of direct interaction between fl uorine agents of slag with hydrogen and oxygen in metal are the most probable reactions of the interaction with cryolite. In more complex mechanism of interaction involving in the reactions, except fl oriental, silica slag and the possible formation of an intermediate product SiF4 г , process of interaction with the fl uorite is more probable. The calculations have shown the feasibility of using Na3AlF6 compounds with fl uorite for hydrogen removal in submerged-arc welding. The calculations have formed the basis for the development of new compositions of fl ux-additives, protected by patents of the Russian Federation.

The paper presents the researches at the temperatures of 1873, 1923, 1973 К and duration of 5 – 30 min of carbidization of briquetted monocharges, consisting of microsilica, formed at the production of silicon and its alloys and diff erent carbon deoxidizers: brown coal and coal-mine semi-cokes, coke fi nes and coke dust. It has been established that the highest indicators are reached at carbidization with the use of brown coal semi-coke of Berezovskii deposits of Kansk-Achinsk basin: the yield of silicon carbide is 97.00 – 97.62 % at its content in the products of carbidization of 82.52 – 84.90 %. The optimum temperature-time conditions and the indicators of carbidization have been defi ned, namely: the temperature of 1923 – 1973 К at the duration of 20 – 15 min. The dominant phase in the products of carbidization is silicon carbide of a cubic structure (β-SiC). As a result of chemical enrichment, the content of SiC in carbide is 90 – 91 %, i.e. it is higher than in abrasive micropowders with the granularity of 1 – 2 μm. The enrichment effi ciency from the impurity of oxides and iron is high and makes 87 – 95 %. For silicon carbide a high content of silica is typical – more than 7 %; that allows considering it as a perspective material for the production of carbide-silicic refractory materials on a silica band. Silicon carbide has been received in the form of micropowder with the particles of irregular form with a size diapason of 0.2 – 1.0 μm.

The dynamics of a system sleeve (pipe) – mandrel – rod of an automatic mill of the pipe-rolling unit was considered. The differential equation of the movement of a mandrel rod of an automatic mill was worked out taking into account the mass of mechanical system changing in time. The dynamic processes in mechanical system sleeve (pipe) – mandrel – rod is presented by coeffi cient of movement dynamism of a mandrel with a core. The features of functioning of rod system of the deduction mechanism of an automatic mill mandrel were established and parameters of dynamism of mechanical system were determined according to the change in time of mass of the rolled pipe. It is shown that at the instant appendix from the center of deformation of constant force in elastic system of mechanisms of the output part possessing a variable in time weight, the maximum dynamism coefficient isn’t equal to two. Its values monotonously change and increase during the fl uctuations of system with the increasing weight. By modeling of dynamic processes in system sleeve (pipe) – mandrel – rod taking into account the change in time of mechanical system mass, the need of stabilization of dynamism of a mandrel with a core to the level of admissible sizes was revealed for the equipment of the output part of an automatic mill.

In the development of ultrasound structurescopy the authors have offered a new approach to the assessment of metal structure by ratio value of amplitude of a middle level of acoustic structural noises to the amplitude of «appear» of Rayleigh waves. The level change of structural noises in 09G2S steel at single-axis tension has been researched. The influence of mechanical stresses, as well as structural metal states on the level of structural noises has been shown. The authors have determined the presence of relation between the parameters of acoustic structural noises and structural state of 09G2S steel. Also the authors revealed the regularity of sharp decrease of the level of structural noises when metal reaches the yield point. It has been experimentally confirmed that the sharp drop of the level of structural noises (the inflection point), when reaching the yield point, confirms a high sensitivity of the method to the changes of metal structure. This fact allows recommending the measurement method of acoustic structural noises to reveal the preparatory stage of the process, connected with the accumulation of the damageability in metal, namely, the stage of accumulation of microimperfection.

The velocity increase of plastic deformation leads to significant changes in the microstructure of metallic materials. The structure and properties of the metal defi ne such factors as pressure value (or impulse), deformation velocity (or the duration of the process) and temperature. The work is devoted to the research of the influence of high-velocity deformation on the microstructure of materials. Using research complex Gleeble 3500 high-speed deformation of steel grade 20 at temperatures of 800, 900, 1000 and 1200 °C was carried out. The microstructure was studied and the microhardness of samples was determined. The principal possibility to provide strain refi nement of low-carbon steel structure up to a grain size of about 400 nanometers during high-speed deformation at temperatures of 800–1000 °C is shown, just as it is achieved at a severe plastic deformation without heating or with a slight heating which doesn’t exceed the recrystallization temperature.

The main features of plastic strain macrolocalization and structure of low-carbon steel after hot rolling and electrolytic hydrogen saturation in a thermostatted three-electrode electrochemical cell at a controlled constant cathode potential have been studied. Using the method of double-exposure speckle photography at different stages of strain hardening the main types and parameters of plastic flow macrolocalization (propagation rate and wavelength) have been identified. The effect of interstitial impurity of hydrogen on the change of the substructure and cementite morphology has been determined using methods of optical and electron microscopy. Attention has been given to the formation of dislocation substructures; bending-torsion of the α-phase lattice has been revealed, as evidenced by the presence of bend extinction contours. The main sources of stress field have been found to be grain and fragment boundaries.

The article presents the research results of the infl uence of non -metallic inclusions on high-temperature plasticity of E76F rail steel. The maximum plasticity of all three zones of the continuously cast ingot, the criterion of which is the degree of shear strain, was established. The results of high-temperature twisting of samples which were heated from 950° to 1250° and soaked for 10 minutes in all three zones of the continuous casting ingot made from rail steel are presented. The presence of oxides and silicates in the rim zone, oxi des and oxisilicates in the zone of radial-columnar crystals, as well as sulfi des, oxides, silicates and alumosilicates in the central zone of the continuous casting ingot were found. It was established that the greatest amount of inclusions is concentrated in the central zone of the continuously cast ingot which leads to reducing of plasticity criterion.

The authors have off ered the algorithm of dual-mode control with the simultaneous identifi cation of the change model of oxygen expense intensity for blowing – carbon dioxide content change in exit gases of steel converter melting and the correction of oxygen expense during the fi nal period of melting. Such a unifi cation was reached at the expense of control action of a step type in the given point of time and its fi xation on the time interval of a transient process from this action, registration of the data of control and output actions at the time interval of a transient process, calculation by these data of model coeffi cient and the size of control action with the use of the received coeffi cient assessment, realization of control actions on the next control interval. The article also presents the results of effi ciency assessment of the proposed control algorithm: the indicator of “smoothness” of the time series of carbon control in metal in the critical point and the percentage of hits of carbon content in steel in the set interval at the turn-down of the converter.

The authors have developed the calculation method for the distance from the upper surface of the roller of fedding roll table to the upper surface of the roller of discharge roll table of the device for cutting of pre-curved stripes, proceeding from conditions of the band cutting force minimization in performing the requirements of its straightness after cutting.