The second part of the review considers properties, application and methods for producing chromium and zirconium diborides. These diborides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Chromium and zirconium diborides exhibit significant chemical resistance in aggressive environments. They have found application in modern technology because of these reasons. Chromium diboride is used as a sintering additive to improve the properties of ceramics based on boron carbide and titanium diboride. Zirconium diboride is a component of advanced ultra-high temperature ceramics (UHTC) ZrB₂ –SiC used in supersonic aircrafts and in gas turbine assemblies. Ceramics B₄C–CrB₂ and B₄C–ZrB₂ have high-quality performance characteristics, in particular, increased crack resistance. The properties of refractory compounds depend on the content of impurities and dispersion. Therefore, to solve a specific problem associated with the use of refractory compounds, it is important to choose the method of their preparation correctly, to determine the admissible content of impurities in the starting components. This leads to the presence of different methods for the borides synthesis. The main methods for their preparation are: a) synthesis from elements; b) borothermal reduction of oxides; c) carbothermal reduction (reduction of mixtures of metal oxides and boron with carbon; d) metallothermal reduction of metal oxides and boron mixtures; e) boron-carbide reduction. Plasma-chemical synthesis (deposition from the vapor-gas phase) is also used to obtain diboride nanopowders. Each of these methods is described.

At the moment, to improve quality of metal (especially low-alloyed), out-of-furnace steel processing technologies are used with complex alloys utilization, which include alkaline earth metals (ALM) in addition to silicon. Study of strontium additives effect on deoxidation and liquid steel modification processes is one of the promising areas of research in field of metallurgical technologies. Thermodynamic modeling of phase equilibria in Fe – Sr – Si –C– O system melt was carried out using method of constructing surface of components solubility in metal. Solubility surface determines stability limits of non-metallic phases formed during deoxidation, depending on composition of liquid metal of the studied system. The  calculation was carried out using equilibrium constants of reactions occurring in the melt during deoxidation, as well as the first order interaction parameters (according to Wagner) of elements in liquid iron. Activity of the oxide melt components was determined using theory of subregular ionic solutions. Activity of the gas phase was calculated taking into account partial pressures. Simulations were performed for two temperatures (1550 and 1600  °C) for fixed carbon concentrations (0 (no carbon in liquid iron) and 0.1 % (low-carbon metal melt)). It has been shown that, in comparison with silicon, strontium is stronger deoxidizing agent in liquid metal. According to the simulation results, liquid oxide non-metallic inclusions of variable composition or strontium ortho- and metasilicates Sr₂SiO₄ and SrSiO₃ (with an increase in strontium concentration) should be the main oxide phases in deoxidation products. Decrease in the temperature of liquid metal leads to changes in phase formation (formation of SrSiO₃ silicate becomes possible).

During contact flash welding of rails, the metal is heated and continuously cooled in the zone of thermal influence. Accelerated heating and subsequent intensive cooling, implemented by the pulsed flashing-off method, lead to the formation of quenching structures. Subsequently, during the operation of the rails welded joint, this leads to the formation of cracks and to brittle destruction. We have investigated the possibilities of using contact heating after welding to avoid the formation of quenching structures in the metal of the welded joint made of R350LHT rail steel. The thermal cycles during welding and subsequent contact heating were recorded. The regularity of formation of the weld metal structure was established including the zone of thermal influence during pulsed contact heating for R350LHT rail steel. It is shown that contact pulse heating slows down the welded joint cooling and prevents the formation of quenching structures. However, contact pulse heating when using suboptimal modes can also lead to the opposite effect. It is determined that with a significant investment of heat by contact heating, cooling rate of the metal exceeds the critical one, transformation process passes through a diffusion-free mechanism with the formation of martensite coarse-grained structure. The use of thermokinetic and isothermal diagrams of austenite decomposition at known thermal welding cycles allows us to significantly narrow the search limits for optimal modes of contact butt welding of railway rails and subsequent contact heating. The use of optimal contact heating modes makes it possible to obtain a minimum length of heat-affected zones with reduced hardness without the formation of quenching structures in the welded joint of railway rails.

Volumetric defects in crystals worsen operational properties of structural materials; therefore, the problem of reducing discontinuities in solid is one of the most important in modern materials science. In the present work, the results of computer simulation are presented that demonstrate possibility of collapse of pores in a crystal in state of shear deformation under the influence of shock waves. Similar waves can occur in a solid under external high-intensity exposure. For example, in the zone of propagation of displacement cascade, there are regions in which occurs a mismatch between the thermalization times of atomic vibrations and the removal of heat from them. As a result of the expansion of such a region, a shock after cascade wave arises. The simulation was carried out based on molecular dynamics method using the potential calculated by means of mmersed atom method. As a bulk defect, we considered extended pores of cylindrical shape, which can be formed after passing of high-energy ions through a crystal, or, for example, when superheated closed fluid inclusions (mother liquor) reach the surface. The study has shown that such defects are the source of heterogeneous nucleation of dislocation loops, contributing to a decrease in the shear stresses in simulated structure. Dependences of the average dislocation density on the shear angle and temperature of the designed cell were established, and the loop growth rate was estimated. Generated shock waves create additional tangential stresses that contribute to the formation of dislocation loops; therefore, in this case, dislocations are observed even with a small shear strain. If during simulation the thermal effect increases, the pore collapses.

Technologies for pressure treatment of metal workpieces using powerful current pulses are becoming increasingly widespread both in Russia and abroad. Unique electromechanical processes are studied and improved in laboratory and production conditions. The process of applying an  electric current to the workpiece is accompanied by a change in its physical properties as a result of the so-called electroplastic effect (EPE). At   the same time, the temperature of the workpiece in the deformation zone increases. For high-quality and reliable operation of the drawing mill with electrostimulated drawing (ESW), it is necessary to use an automatic system for regulating the force and temperature. In order to implement the temperature control circuit, it is necessary to synthesize the transfer function of the control object – steel wire processed by pressure (rolling or drawing). Synthesis and analysis of parameters of the model of temperature control object are considered. The known relations are used: dependence of the pulse generator power on the calculated parameters (initial temperature, diameter, specific weight and electrical resistance of the workpiece, pulse duration); dependence of  the RMS current of the generator on the amplitude and frequency of pulse reproduction; dependence of the magnetic permeability of the workpiece on its temperature; and dependence of the specific electrical resistance of the conductor material on temperature. In MATLAB – Simulink medium, a model of the temperature control object is synthesized as a function of the parameters of generator of high-power current pulses (amplitude and frequency), as well as the parameters of the workpiece to be processed (diameter, sample length, linear velocity, initial temperature, and resistivity at the initial temperature). The model is analyzed, and transients under different operating modes are presented. Using the developed model, the dependences of the temperature, power, and equivalent resistance on parameters of the generator and the workpiece are obtained for different generator pulse frequencies and workpiece diameters. The developed model can be used for laboratory studies of the electroplastic effect, as well as in production in auto-control systems with electrostimulated drawing in order to implement the object of regulation in the form of a model.

Crushing machines are part of the charge departments of blast-furnace and steel-making shops of metallurgical enterprises. One of the main indicator of the crushing process is its energy efficiency. It is determined by the mass of crushed material when consuming a  unit of electricity. The article considers various methods of crushing brittle materials and the design of crushing machines for their implementation. The  analysis of the crushers has shown that impact crushers are the most energy-efficient. However, due to a significant drawback (the yield of a  suitable product is very small), they are practically not used in the metallurgical industry, in which high requirements are imposed on the finished product fractional composition. In the metallurgical industry, compression crushers are widely used with approximately the same specific energy intensity, that is, with the same energy consumption for the destruction of a unit volume of material of equal strength. Compression fracture is the most energy intensive crushing method known. In single-roll crushers, a  piece of material is fed into the gap between a roll and a solid, stationary plate. During the operation a complex stress state is generated in the destructed material. Compressive forces act on a piece of crushed material, causing normal compressive stresses in it, and an internal torque, causing shear stresses. This is achieved by the reduction in energy on crushing by 20 – 30 % in comparison with crushers operating in compression (all other things are equal). The  authors describe the design of a crusher, in which the destruction of the processed material occurs due to the forces acting on the crushed piece in one plane towards each other. In this case, only shear stresses arise in the processed piece. The use of crushers, in which the destruction of the processed material occurs due to generation of only tangential stresses in  a  piece, can reduce the energy consumption per unit of finished product by almost a half. The design of such crushers is a promising direction in the development of machines intended for crushing.

A two-level control system for the temperature mode of smelting, out-of-furnace processing and preparation for casting of low-carbon steel G/ET is proposed in the conditions of BOF shop-2 of JSC “United West Siberian Metallurgical Combine”. Depending on the technological scheme, it is possible to design various control systems for the steelmaking complex with sequential, parallel and combined inclusion of individual operations and processes. The control system of a sequential group of objects is considered on the example of steel G/ET. The control system includes an external control loop that allows coordinated control of the shop departments by optimizing the mode of technological process conducting at the facility, taking into account the actual operation performed at the previous facility. The implemented nonparametric algorithm of dual control allows the decision-maker to perform joint operational adjustment of control actions for local control loops. The temperature mode of the melts of low-carbon steel G/ET is analyzed and it is revealed that the processing time of the steel ladle at each stage of the BOF – CCM technological route has a significant impact on the steel temperature mode. In accordance with this, the criteria for temperature control quality are formed. The results of computational experiment showed that the introduction of a control unit with a decision-maker contributes to the rational control of metal temperature mode in the BOF – CCM site, and as a result, obtaining a given chemical composition and temperature of steel within narrower limits. It allows one to eliminate deviations from the contact schedule of the main units, and to increase the number of melts in the series and the rate of continuous casting.