Vol 2019, No 6 (2019)

An algorithm is developed to estimate the rate of charge melting in the electric arc furnace laboratory and its geometric sizes. An electric-arc instability index is proposed as a parameter for on-line control of the heat state of the bath and the rate of metal scrap melting. In practice, a decision about turning off a furnace in melting a charge or about the beginning of the end oxidation stage of a heat is delayed, which leads to an increase in the time of furnace operation under an electric current and in the specific electric power consumption.

A model is developed for an electromagnetic stirrer using a traveling magnetic field. Electromagnetic and hydrodynamic problems are simultaneously solved for a two-dimensional case by a finite element method. The behavior of impurities in a turbulent flow is calculated using the Stokes law. A nonstationary magnetic field is shown to be applied. The calculated spatial distribution of impurities has a homogeneous character in the liquid metal volume. The model is verified by measuring the magnetic induction in an experimental setup.

The following results of studying electric discharges over a wide pressure range and designing technological equipment based on these results and performed in Bauman Moscow State Technical University are presented: a magnetically controlled argon torch for welding, soldering, and heat treatment; a small electric arc melting furnace; and technology and equipment for the cleaning of metallic articles from contaminations and for reaching the required surface roughness according to a functional purpose.

The processes of fracture of clad electrode holders made of a steel–copper bimetal during their operation are considered. Recommendations are made to increase the service life of the electrode holders.

Experiments on plasma heating of a burnt periclase–carbon refractory are performed. The heating rate is high, more than 1000 K/h. The thermophysical properties of the burnt refractory are refined using the experimental results. The burnt periclase–carbon refractory has a lower thermal conductivity than the green refractory (9.5 and 25 W/(m K), respectively) and a higher emissivity factor (0.6 and 0.3, respectively). The experimental data are used to refine the parameters of the CFD model of plasma heating of the periclase–carbon refractory, which will allow one to simulate the process of heating more exactly.

Dense defect-free 10Kh3A steel ingots with an overequilibrium nitrogen content (0.1–0.17 wt %) are formed by electroslag remelting under nitrogen pressure in a DEShP 0.1 pilot furnace (All-Russia Institute of Aviation Materials). A method is developed for calculating the solubility of nitrogen in multicomponent melts, including model steels, under its atmospheric and working pressure in the furnace chamber. This method determines the nitrogen content in liquid and solid metals and can be used to form 10Kh3A steel ingots with a dense homogeneous structure. Distributions of nitrogen and other alloying elements over the ingot height and cross section are found. The calculated nitrogen solubility in the metal is in agreement with experiment one.

Experimental data are used to estimate the possibility of the deposition of a wear-resistant nickel-based VKNA-2M intermetallic alloy onto the contact surfaces of the airfoil shroud platforms of the gas turbine blades in a high-temperature gas turbine engine (GTE) by facing in an argon atmosphere. A technique is proposed to restore the geometric sizes of the wear-resistant coatings on the airfoil shroud platforms of gas turbine blades to increase the functional properties of the repaired coated parts.

The specific heat of U8 steel is measured after deforming cutting, quenching from furnace heating into water, and subsequent heating in a calorimeter in the temperature range 100–400°C. The temperature dependences of the specific heat after deforming cutting and furnace quenching have substantially different characters, which is due to a nonequilibrium state of the structure in the material after quenching by deforming cutting. The change in the enthalpy of U8 steel during its heating for these types of quenching is calculated.

The properties of the composite galvanic coatings deposited using the powder fabricated by the electroerosion dispersion of the wastes of ShKh15 steel as a hardening phase are studied. The microhardness of this coating is shown to be higher than that of the coating deposited using a standard powder by 20%. The adhesion and cohesion strengths of the coating exceed 190 N.

The physicochemical interaction in the ZrSi₂–ZrSiO₄ system at temperatures higher than 1620°C under the conditions of molecular oxygen deficiency is established and experimentally confirmed. Elemental silicon is reduced simultaneously with the oxidation of zirconium to the thermodynamically stable ZrO₂ phase. The mechanism and steps of the interaction processes are proposed.

A process of melting a 32NKD superinvar alloy from industrial wastes in a 1100-kg FS (core-free) induction furnace is developed. The preparation of a charge, namely, fraction composition, oxidation, the content of harmful impurities, and a method of charging, is considered in detail to ensure the maximum resistance of a crucible and to optimize melting. The methods of decreasing the height of the meniscus that forms on the melt surface because of the specific features of induction heating and the related features of slag formation are analyzed.

The effectiveness functions of pure and mixed strategies are used to estimate the commercial attractiveness, the competitive incentives, and the development of operation activities of the leading Russian metallurgical and banking corporations. Positive dynamics and favorable possibility of their development at the present day period of economic recession and application of restriction sanctions to Russian economy are noted.