The properties, application, and methods for producing titanium and vanadium carbides are considered. These carbides 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. Titanium and vanadium carbides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in  modern technology. These carbides are used as surfacing materials for the application of wear-resistant coatings to steel products. It is possible to  use them as catalysts in organic synthesis. Titanium carbide is used in tungsten-free hard alloys, carbide steels. Due to its high hardness, it is used as an abrasive and as a component of ceramic cutting tools. Vanadium carbide serves as an inhibitor of the growth of tungsten carbide grains in hard alloys. The properties of refractory compounds depend on the content of impurities and dispersion (particle size). To solve a specific problem associated with the use of refractory compounds, it is important to choose the right method for their preparation and to determine the permissible content of impurities in the initial components. This leads to existence of different methods for the synthesis of carbides. The main methods for their preparation are: synthesis from simple substances (metals and carbon), metallothermal and carbothermal reduction. Plasma-chemical synthesis (vapor-gas phase deposition) is also used to obtain carbide nanopowders. A characteristic is given to each of these methods. Information on the possible mechanism of the processes of carbothermal synthesis is presented.

Currently, duplex stainless steels are increasingly used in industry. Austenite and ferrite in these steels are in approximately equal proportions. During manufacture of cast products from these steels, a chemical and structural heterogeneity is formed in the castings, for the elimination of which heat treatment is carried out. In practice, within the framework of one class or even one steel grade, the chemical composition and, as a consequence, the phase ratio can vary over a wide range without reaching their optimal values. In this paper, the authors investigated the influence of chemical composition and solidification conditions on the structure and properties of cast duplex stainless steels and developed thermodynamic criteria for the selection of casting alloys, taking into account the temperature of beginning of the polymorphic transformation of δ-ferrite into austenite and the average equilibrium rate of this transformation. It was found that in the studied steels with 21 – 26 % of chromium, crystallization proceeds with the formation of δ-ferrite dendrites, and austenite is formed in the solid metal at the places of the former interdendrite spaces. It is shown that at cooling rates, which are realized in practice when obtaining, for example, casings of centrifugal pumps or other products of a similar size, the transformation of δ-ferrite into austenite is practically suppressed when the temperature reaches 1180 – 1200 °C. On the basis of this, a criterion for the development of compositions with the required phase ratio without heat treatment was proposed. The evolution of the structure during heat treatment at temperatures of 1050 – 1250 °C was studied and it is shown how by choosing the optimal temperature of annealing and quenching, depending on the actual chemical composition of steel, it is possible to achieve an acceptable level of pitting potential in steel with a lower alloying, and vice versa, non-optimal heat treatment of a high-doped alloy leads to a catastrophic decrease in corrosion resistance. It is shown that in the steels under consideration optimal properties are achieved at 70 % of δ-ferrite.

The thermal state of liquid metal at the continuous steel casting stage was studied by methods of correlation analysis under the assumption that measurable objects are random variables. The thermal state of metal melt is characterized by the values of metal temperature T_n at a given stage and duration of stages τ_n , and is described by the integrated index – cooling rate W_n. The cooling rate is the differential quotient of the liquid metal temperatures at the beginning and end of the stage to the duration of this stage. The metal cooling rate at various stages of continuous steel casting phase was calculated. The first stage includes the period from the end of metal processing at the integrated steel processing unit to the beginning of vacuum degassing. The second stage includes the period from the beginning of vacuum degassing to its completion. The third stage includes the period from the end of vacuum degassing to the first temperature measurement in the tundish.  Then there are periods of consecutive temperature measurements in the tundish. The study established that metal cooling rates vary significantly depending on process stages. The absolute values of the cooling rate differ by more than an order of magnitude. The minimum rate of metal cooling was recorded in the tundish. Its value was 0.09 °С/min. The maximum metal cooling rate was detected during tapping from the steel-teeming ladle into the tundish. In this case, the cooling rate was 1.43 °С/min. 
The main factors affecting the metal cooling rate were determined. These factors include: the initial temperature of liquid metal after the end of processing at the integrated steel processing unit; the temperature of liquid metal after vacuum degassing; the presence on the liquid metal surface of the oxide solution formed by slag-forming mixtures; availability and effectiveness of heat insulating mixtures; as well as the heat insulating properties of refractory linings. During vacuum degassing, the metal cooling rate was essentially determined by convective energy losses and energy losses for inert gas heating. After the vacuum degassing stage, the cooling rate significantly decreases due to the use of heat insulating mixtures. The highest rate of metal cooling is achieved when it passes through the steel outlet channel and the metal protection tube during tundish filling. The lowest metal cooling rate was found in the tundish due to the presence of a porous shotcrete layer with low thermal conductivity.

The article discusses the features of kinematics of the working tool in form of circular sector during hardening by pendulum surface plastic deformation (SPD), which is carried out due to two successive processes – rolling and sliding in the contact zone of the deforming element with the blank. Forecasting of the possibility of its application for finishing and hardening processing of cylindrical parts such as shafts and axles is presented; the kinematic parameters of the pendulum SPD process in a rectangular coordinate system are described. Based on analysis of the components of motion types (rotational, translational, oscillatory) of the blank and tool, functions of the trajectory length, magnitude of the resulting velocity and acceleration were determined, which make it possible to control the technological parameters and modes of the pendulum SPD process. Reliability of the kinematic analysis is confirmed by the results of simulation with ANSYS  19.1 computer program. The results of dynamic modeling showed that under the same hardening conditions with a stationary position of the working tool and its opposite rotation with the blank, the intensity of temporary stresses increases by 10 % and 17 %, respectively, compared to the rolling scheme. With pendulum SPD, the intensity of temporary stresses increases sharply and reaches a maximum value (485 MPa), the distribution of which is uniform in comparison with other methods. In addition, regularity of the intensity distribution of temporary stresses over the cylinder depth is shown, where it is clear that in the case of SPD by sliding, the depth of plastic deformation h has a higher value compared to the SPD by rolling (by 1.5 – 2.3 times). Under the same hardening conditions, the highest value of the depth of the hardened zones is obtained with pendulum SPD (h = 2.8 mm), which leads to changes in the physical, mechanical and operational properties of the blank deeper surface layer.

On basis of mathematical modeling and object-oriented programming, a computer information-modeling forecasting system (IMFS) for thermal mode of top lance barrel (TLB) of oxygen converter was developed in order to fulfill the urgent and economically feasible task of determining the compliance of input technological parameters with certain safety criteria for conducting converter melting.The program was created in the form of a Windows-oriented application by refining the previously developed mathematical model of the temperature mode of the top converter lance barrel using the object-oriented programming language C# in Microsoft Visual Studio 2019 IDE. The mathematical model provides the solution of differential heat conduction equation in cylindrical coordinates (two-dimensional formulation) with assignment of the initial (temperature distribution in the computational domain) and boundary conditions of the II and III kind (respectively, on the outer and inner surfaces of the TLB). The finite-difference approximation of the heat conduction equation and boundary conditions was obtained by the integro-interpolation method (balance method). A numerical sweep method (modified Gauss method) and an unconditionally stable implicit scheme were used to calculate the temperature field. Thermophysical values were obtained by approximating the corresponding tabular values. The application does not put forward special requirements for the computer infrastructure, operates locally (without the need for access to Internet), does not require special skills to work with it, having an intuitive user interface: the working area of the program consists of three windows (sections), in which the results of calculating the thermal mode of the TLB are displayed. The developed IMFS allows evaluating the design and technological parameters of the top blowing device as a criterion for its safe operation. Its application in the “advisor” mode ensures the optimal design of the top oxygen lances with a rational water cooling system in order to ensure the proper thermal mode of the TLB throughout the entire operation period, as well as trouble-free operation of the blowing device, which is especially important for the conditions of converter shops in Ukraine equipped with outdated designs of top lances with low service life.

Zero-waste technologies are technically and technologically based mainly on environmental protection systems (EPS). Such systems help to arrange waste recycling into the technosphere rather than polluting the environment. The article gives a brief review of the methods and technologies of ferrous metallurgy waste recycling. Simple patterns in which the interrelations between devices for environmental protection against solid, liquid and gaseous wastes are not arranged, cannot provide the necessary level of zero-waste production. Only integrated multistage, multilevel systems of raw materials processing and waste recycling, including devices and technologies for processing of waste flows in various phase states, can create a high degree of zero-waste production. The design of such systems startswith the description of outgoing substances and energy flows from process plants, the formation of structural variants, operating principles (technologies) and equipment (devices) of system components. It is from these that the optimal variant will be chosen. The purpose of optimizing a protection system is to minimize the mass of waste sent into the environment. This provides for environmental and industrial safety, and takes into account the technical and economic constraints on the possibility of implementing the selected EPS structure. The study proposes a procedure for forming the structure of the system, including production, environmental protection devices, and the natural environment.  Interrelations between the system components are represented by energy flows and masses of substances. The study also proposes an example of arranging the system structure including interrelated subsystems for processing (treatment, decontamination, etc.) of gases, wastewater and solid waste. EPS devices in general can form outgoing flows of substances, which, depending on their properties (hazard, usefulness and phase state), can be directed to the environment, to the next level (stage) protection devices, as well as to production for replacing raw materials or obtaining products. An example of organizing the structure of an integrated multistage and multilevel system of environmental protection against emissions, including subsystems for treating secondary waste in gaseous, liquid and solid states, is considered. The proposed procedure for forming the environmental protection system structures can be applied to other industries.