Physicochemical characteristics of the melt of nitrogen-alloyed steel of 04Kh20N6G11M2AFB grade (nitrogen content 0.47 ÷ 0.49 %) were investigated by the method of torsional vibrations of a crucible with a metal in the atmosphere providing a stable nitrogen content during the experiment (80 % nitrogen and 20 % helium). Using sensitivity of the method to aggregate state of the test substance, at a heating rate of 0.0033 ÷ 0.0050 K/s, the liquidus temperatures were experimentally determined for 04Kh20N6G11M2AFB steel (1660 ÷ 1666 K) and lownitrogen steel ([N] = 0.063 %) with identical content of other elements (1685 ÷ 1690 K). This made it possible to recommend the value of the coefficient – 60 K/% [N] for the calculated assessment of the effect of nitrogen on liquidus temperature of complex and high-alloy steels. It is shown that the viscosity of the melt of 04Kh20N6G11M2AFB steel has a relatively high level ((11.5 ± 0.7)·10^–7 m²/s) in comparison with the traditional ((8.2 ± 0.2)·10^–7 m²/s) austenitic steels with a relatively small partial effect of nitrogen. A significant non-equilibrium of the melt structural state of this steel was established by high-temperature viscometry methods. Comparative analysis of polytherms and isotherms of the melt kinematic viscosity for 04Kh20N6G11M2AFB steel and its low nitrogenous ([N] = 0.063 %) analogue made it possible to conclude that the presence of nitrogen at concentrations close to saturation plays a decisive role in the level of non-equilibrium of the melt and low rate of its relaxation. It was confirmed as a result of special experiments on the saturation of low-nitrogen steel with nitrogen, during which a sharp increase in non-equilibrium of the melt structural state was recorded with achievement of nitrogen concentration in the metal of limiting values (0.45 ÷ 0.50 %). The principal possibility of increasing and stabilizing the operational properties of corrosion resistant nitrogen-alloyed steels is indicated by reducing non-equilibrium of the melt structural state by eliminating the excess of nitrogen concentration limits for the considered chemical composition.

The possibility of using a barium-strontium modifier as a gasprotective and refining additive for welding the fluxes based on crushed slag from the production of ferrosilicomanganese is presented. The barium-strontium modifier BSK-2 produced by JSC “NPK Metalltekhnoprom” according to TU 1717-001-75073896–2005 was used as a material for the study. The base of the welding flux was silicomanganese slag produced by the West Siberian Electrometallurgical Plant. The research work on new welding fluxes and flux-additives was carried out using the equipment of the Scientific and Production Center “Welding Processes and Technologies” and the Center for Collective Use “Materials Science”. The use of barium-strontium flux additive was carried out in two ways. In the first option, the flux-additive was made by grinding barium-strontium to a dust-like fraction of less than 0.2 mm with further mixing with liquid sodium glass, drying in a furnace, crushing and separating a fraction of 0.45 – 3.00 mm. In the second option, the flux additive was used in the form of dust with a fraction of less than 0.2 mm. The additives were mixed at a ratio of 2 – 10 % of mass of the slag produced by silicomanganese. Surfacing of the samples was carried out with a welding wire of the sv-08GA grade on a substrate of steel grade 09G2S with a thickness of 20 mm. Quality of the deposited metal was studied, the chemical compositions (deposited layers, slag crusts, the used flux) were investigated by X-ray fluorescence method on XRF-1800 spectrometer and by atomic emission method on DFS-71 spectrometer. The degree of contamination with non-metallic inclusions (non-deforming silicates, point oxides, sulfides) was studied using OLYMPUS GX-51 optical microscope in the magnification range from 100 to 1000. The laboratory studies on the surfacing of steel samples have shown that due to introduction of a flux additive made from barium-strontium modifier, the metal is refined, and the concentration of sulfur and phosphorus decreases. The use of a mixture of a barium-strontium modifier with liquid glass as an additive is preferable to the use of an additive in the form of a dust. It was revealed that the best samples from the point of view of the degree of contamination of the deposited metal with nonmetallic inclusions are samples made using no more than 8 % of barium-strontium flux additive.

Metallurgical slags accumulate in large quantities. For further disposal, they must have the certain technical properties. Among the main factors there are chemical and mineral compositions of slags, which affect their final properties. Elemental composition of Zaporozhstal dump blast furnace slag, determined by electron probe microanalysis, makes it possible to characterize the slag fractions in terms of toxicity. Potassium, sodium, sulfur, chlorine, copper and titanium, which are not part of the minerals, are recorded by scanning electron microscope; this suggests that they are sorbed by mineral particles surface. The maximum content of potassium, sodium and titanium is typical for the 2.5 – 5.0 mm fraction. Slag contains an insignificant (less than 1 %) amount of metals – iron, titanium and copper, which belong to the third hazard class of the substance; this does not impede further use of the slag. The third hazard class of dump blast furnace slag has been identified. Volume activities and effective volume activities of granulometric slag fractions have been determined by gammaspectrometric method. ⁴⁰K, ²²⁶Ra and ²³²Th natural radio nuclides have been found. It has been proven that slag and its individual fractions belong to the first class of radiation hazard and can be used in construction without restrictions. Zaporozhstal dump blast furnace slag is characterized by high hydraulic activity with an increase in absorption of calcium oxide CaO over time. Dump blast furnace slag can be recommended for production of binders (Portland cement and slag Portland cement) in terms of combination of chemical parameters: to moderately hazardous production wastes of the first class of radiation hazard with manifestation of high hydraulic activity.

A mathematical model was developed and a mechanism was proposed for the formation of nanoscale structural-phase states on the example of rail steel at long-term operation. It was believed that during intense plastic deformations, the material behaves like a viscous incompressible fluid. In order to take into account the sliding of the wheel relative to the rail, a two-layer fluid model was proposed, the top layer of which slides at a certain speed relative to the first. In this case, the Kelvin-Helmholtz instability develops. For each layer, we have written the Navier-Stokes equations and kinematic and dynamic boundary conditions. Solution of the obtained system in the form of normal perturbation modes was carried out on the basis of assumption of the viscous-potential material flow. In this approximation, it was believed that viscosity effects occur only at the layer interface. A dispersion equation was derived, which was analyzed using a graphical representation of the functions included in the analytical solution. A range of characteristics of the material and parameters of the external influence (the velocity of the layer) was established, at which two peaks are observed in dependence of disturbances growth rate on the wave number. The first (hydrodynamic) maximum is due to the motion of the layers relative to each other; the second is associated with the effects of fluid viscosity. Approximate formulas were obtained for dependence of the growth rate of perturbations on the wave number. Conditions for realization of only one maximum were found. The viscously determined maximum at slip velocities of the order of 1 m/s can be in the nanoscale wavelength range. Assuming that the white layer in the rails during long-term operation is formed mainly due to the action of intense plastic deformations, we believe that the obtained results detail the mechanism of white layers formation in the rails in this case.

The authors have studied the effect of plasma surfacing and s sequent high-temperature tempering on surface morphology and elemental composition of deposited coatings of high hardness chrome tungsten steel, such as R18, additionally alloyed with aluminum and nitrogen (0.86 % C; 4.84 % Cr; 17.0 % W; 5.40 % Mo; 0.50 % V; 0.65 % Al; 0.06 % N). 30KhGSA steel, which has a complex of high mechanical properties, is used as the base metal. Specific feature of the surfacing was low-temperature preliminary and concurrent heating, as well as thermal deposition cycle, consisting of three main stages. At the first stage with limited heating time and increased cooling rate at high temperatures, grain growth and decomposition of austenite was prevented with formation of equilibrium low-strength structures. At the second stage deposited metal stayed in austenitic state. At the third one, the deposited metal with low tendency to crack has been obtained. Using the method of scanning electron microscopy and X-ray spectral microanalysis, surface morphology and elemental composition of the coatings were studied in two states: immediately after surfacing and in state after surfacing and high-temperature tempering. It has been established that in the first case, the main part of material surface is pearlite grains. At the joints and along grain boundaries, cementite of complex composition and compounds based on iron, tungsten and molybdenum, of variable composition (Fe₄W₂N, FeWN₂ and Fe₄W₂C) are located. Solid solutions based on aluminum and, possibly, the AlN phase also present. High temperature tempering leads to hardness increase, change in shape and size of grains, quantitative change in elemental composition, and uniform distribution of alloying elements over the volume of material. The proposed method of plasma surfacing with high temperature tempering provides all the basic requirements for the surface of working rolls of cold rolling, which is confirmed by test results of the batch of deposited rolls.

In conditions of converter shop of JSC “ArcelorMittal T tau” the authors have developed and implemented the technology of direct microalloying of structural steels with boron. Microalloying was carried out due to 2 boron recovery from the slags of the CaO – SiO₂ – B₂O₃ – MgO – Al₂O₃ system formed in ladle furnaces. The use of the developed technology provided in steels 08KP, 3SP, 3PS and 09G2S boron content of 0.0016 – 0.0050 %, a sufficiently high degree of metal desulfurization 36.8 – 51.7 %, reduction in manganese ferroalloys consumption by 0.3 – 0.6 kg/t of steel, improving the environmental situation by eliminating the use of fluorspar. For 09G2S steel the yield σ_y and tensile σ_t strengths are higher for the experimental metal then for the steel without boron by an average 27 and 24 MPa, respectively. Percentage of elongation of the metal with boron increased by an average 0.2 %. Grain-size index of rolled metal of 08KP steel with a thickness of 2.0 – 2.5 mm, containing 0.001 % of boron and a manganese concentration lowered to 0.18 %, reaches 10.0 in contrast to 9.0 for the heats of the current production. The yield σ_y and tensile σt strengths are on average by 6.0 and 5.0 MPa higher for an experimental metal than for a comparative one. Percentage of elongation δ reaches 36.3 % for the experimental metal unlike 33.3 % for the heats of the current production. Experimental rolled metal of 3PС steel with lower concentration of manganese lowered by 0.02 % and with an average boron content of 0.001 % is characterized by an increased yield strength σ_y , tensile strength σ_t (on average by 2.0 and 9.0 MPa) and percentage of elongation δ reaching in average 21.0 %, and fine-grained structure. Rolled metal of 3SP steel, microalloyed with boron, with a thickness of 4 mm that contains manganese content reduced to 0.43 % is characterized by improved strength properties with preservation of plastic characteristics. The absolute value of the yield σ_y and tensile σ_t strengths of steel are by 4.0 and 2.0 MPa higher than the strength characteristics of steel without boron.

Alloys of the Ni – Co system are widely used in industry. B ron is one of the alloying components in these alloys. The study of thermodynamics of the oxygen solution in boron-containing Ni – Co melts is of considerable interest for the practice of such alloys production. Thermodynamic analysis of oxygen solutions in boron-containing Ni – Co melts has been carried out. The equilibrium constant of interaction of boron and oxygen dissolved in the nickel-cobalt melts, the activity coefficients at infinite dilution, and the interaction parameters characterizing these solutions were determined for melts of different composition at 1873 K. During interaction of boron with oxygen in Ni – Co melts, the oxide phase, in addition to B₂O₃, contains NiO and CoO. The values of the mole fractions of B₂O₃, NiO and CoO in the oxide phase for different boron concentrations in Ni – Co melts were calculated at 1873 K. In the case of nickel melt at boron contents above 0.01 %, the mole fraction of boron oxide is close to unity. As the cobalt content in the melts increases to 20 %, the mole fraction of boron oxide in the oxide phase decreases, and then practically does not change. Dependences of the oxygen solubility on the contents of cobalt and boron in the studied melts were calculated. The deoxidation ability of boron decreases slightly with increasing cobalt content up to 20 %, and then increases with increasing cobalt content in the melt. Boron contents in minimum points on the oxygen solubility curves and the corresponding minimum oxygen concentrations were determined.

Stress state of metal in deformation zone during introduction of the separating collars of the grooved die into continuously casted steel slab was calculated for production of section billets on the unit of combined continuous casting and deformation. Calculation of axial, tangential and equivalent stresses arising in deformation zone of metal was made in four sections of deformation zone and its results are presented in specific points and lines. View of the section of deformation zone and location of specific points are provided. The stress state of metal in zone of cyclic deformation at formation of three steel section billets from continuously cast slab by separating collars of grooved die on the unit of combined continuous casting and deformation was determined by solving extensive problem of elasticity with the finite element method using the ANSYS package. The results of calculation of axial, tangential and equivalent stresses according to Mises in deformation zone are given in form of graphs and tables for working surfaces in four cross sections. The values and regularities of distribution of these stresses along the length and width of deformation zone were determined. The character of axial stresses distribution by characteristic lines located along the length of deformation zone is shown. Values of the highest compressive and tensile axial stresses arising in deformation zone during introduction of separating collars of grooved were obtained for the unit of combined continuous casting and deformation.

The paper presents shot blasting (SB) as the most common method of arrangement of temper mills rolls surface microgeometry, providing required roughness of the cold-rolled strip. The surface riffing studies were carried out at the Willibrator industrial unit; metallographic studies were performed using MEIJI 2700 optical microscope and JSM-6490LV scanning electron microscope. Refinement of the surface layer structure during interaction of the roll material with the grit was revealed. In the work the lower bound method, one of the methods of plasticity theory, is used for theoretical analysis of the SB process. To make computations easier, the roll microcave is approximated to spherical shape. Quantitative estimates of deformation degree and the depth of hardened layer were determined by speed of the grit and hardness of the roll surface. The depth of hardened layer is obtained by the size of used grit, and to a lesser extent, by the speed of grit impact on the roll surface and textured surface hardness. It has been searched out in literature that increase in hardness by one unit leads in average to 3 % increase in resistance. Thus, SB application allows reduction of time of rolls rehandling of temper mills by 6.0 – 10.5 %, depending on application modes of rolls riffing with grit. Analysis of microstructure have shown that increase in hardness of the surface layer is a consequence of refinement of its structure in process of interaction with the grit. It has been revealed that increase in hardness of the surface layer leads to an increase in its wear resistance and fatigue strength. The authors of the work have found that at speed of 60 m/s the hardness increases by 3.5 units.

The paper presents a mathematical model optimizing the choice of material and morphological structure of the shell mold (SM), which has the highest resistance to cracking when pouring liquid metal into it. To solve this problem, the theory of small elastoplastic deformations and the heat equation, as well as proven numerical methods, were used. The objective function min – max was constructed from control variables characterizing the properties of the molding material of the shell. The process of heating an axisymmetric shell mold was considered when pouring liquid metal into it. The resistance of the shell form was estimated by the stresses arising in it. An algorithm for solving this problem was compiled. Using numerical schemes and program complexes developed in previous studies, an algorithm for solving the optimization problem was constructed and the values of control variables were found in which the shell mold does not break even in the presence of a rigid process – pouring steel into a cold shell mold. Analysis of the influence of weight of each of the found parameters on the value of the constructed objective function is given. Using a mathematical experiment, the morphological structure of the shell mold was studied. The shell mold of five layers is considered. The corrected system of equations makes it possible to take into account the properties of the layers made of different materials. Calculations were performed when the layer of the shell mold from material found by optimization occupies different positions in its cross section. In this case, the remaining layers of the mold are made of traditional ceramics. The optimal location of this layer was found. It is shown that the presence of several layers with the found properties does not affect the increase in crack resistance of the shell mold.

Electromechanical installation containing electromagnetic s noid with a piston operating in reciprocating motion mode has been developed. Technologies with similar operating modes are widely used in various industries (mechanical engineering, metallurgy, mining, mechanics, robotics, as presses for forging and stamping, as well as jack-hammers in crushing devices for coal, ore and rock). An economically effective generator of high power unipolar current pulses (with unique systems that allow adjustment of the main parameters in a wide range and with high speed: the frequency of pulse reproduction, amplitude) was used as a power source for electromechanical installation. The principle of operation of the generator is based on periodic discharge of pre-charged capacitors to a low-resistance active-inductive load. Generator contains power unit, consisting of a capacitor discharge unit for load; a generator control system (GCS), consisting of a capacitor charging unit (reversible thyristor converter with counter-parallel connected thyristor bridges); a recharge unit and an automatic control system of the ACS. According to the known equations, parameters of mechanical and electrical parts of the electromechanical installation were calculated: initial coordinate of the piston; magnetomotive force arising from change in inductance L(x); spring force; the force of resistance to the piston, proportional to the speed of its movement; force action on the piston; amplitude, duration and frequency of reproduction of current pulses. A simulation model of the installation has been developed in the MATLAB-SIMULINK environment. The graphs of transient processes during operation of the installation at idle and under load were built. Analysis of the operating modes of the installation was carried out. Developed electromechanical installation for influencing load with the aim of its destruction or deformation with a system of automatic control of parameters makes it possible to regulate process parameters with high speed: force and distance traveled by the piston.