卷 2019, 编号 6 (2019)
- 年: 2019
- 文章: 18
- URL: https://journals.rcsi.science/0036-0295/issue/view/10571
Manufacture of Ferrous and Nonferrous Metals
Steel Semiproduct Melting Intensification in Electric Arc Furnaces Using Coordinated Control of Electric and Gas Conditions: II. On-Line Control of the State of the Charge and Melt Zones in Electric Arc Furnaces
摘要
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.
Simulation of Metallurgical Processes
Impurity Distribution in a Two-Sided Electromagnetic Stirrer
摘要
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.
Metallurgical and Electrothermal Equipment
Electric Arc Vacuum Technologies and the Related Equipment
摘要
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.
Experience of Designing a Short Circuit for an Ore-Thermal Furnace
摘要
The experience of modification of ore-thermal production is described. A rectangular furnace is replaced by a round ore-thermal furnace at a retained power supply, namely, a three-phase furnace transformer with star-connected terminals. Unique design solutions are proposed to achieve the maximum possible level of introduced useful power and the minimum inductive reactance of the secondary current lead.
Specific Features and Problems of Operation of the Clad Electrode Holders in Electric Arc Furnaces
摘要
Manufacture of Special Metal Products
Plasma Heating of Periclase–Carbon Refractory
摘要
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.
Special Electrometallurgy
Technology for Producing a Low-Alloy Martensitic 10Kh3A Steel with an Overequilibrium Nitrogen Content
摘要
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.
Influence of the ESR Parameters on the Removal of Sulfur
摘要
The influence of the ESR parameters, namely, the flux composition, the melting rate, the electric current, the type of power supply, and the ac frequency, on the removal of sulfur is considered. These parameters are shown to play a key role in the removal of sulfur. To study the influence of the type of power supply on the desulfurization of 30Kh13 steel during ESR, we remelted ingots using both an alternating and direct current of both polarities under comparable (except for a power supply) conditions The experimental results demonstrate that the removal of sulfur for a direct current of both polarities is lower than in the case of an alternating current and that the reversed polarity leads to better desulfurization than the straight polarity does. The maximum desulfurization of ac ESR is 83%, and the desulfurization by ESR using a direct current of straight and reversed polarity is 33 and 72%, respectively.
Hardening and Coating Technologies
Technology for the Deposition of Wear-Resistant Coatings on the Airfoil Shroud Platforms of GTE Turbine Blades
摘要
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.
Thermal-Barrier Coatings with an External Magnetron-Sputtered Ceramic Layer for High-Temperature Nickel Alloy Turbine Blades
摘要
The results of laboratory isothermal and cyclic heat-resistance tests of ion-plasma thermal-barrier NiCrAlY (Re, Ta, Hf) + AlNiY (Hf) + ZrYGdO coatings, which were applied on samples of high-temperature VZhM-4 alloy containing rhenium plus ruthenium, VZhM5Y alloy containing rhenium, and intermetallic VKNA-1V alloy, are reported. An external ceramic layer of thermal-barrier coatings (TBCs) is applied by the magnetron sputtering of Y- and Gd-containing zirconium alloy targets and has a columnar structure. The effect of TBCs on the long-term strength at a test temperature of 1000°C and on the high-cycle fatigue at 900°C is studied. It is shown that, according to the test results, the minimum damages of the ceramic layer and the minimum mass losses are observed for the VSDP-41 + VSDP-16 + VTsS-4 coating applied on the high-temperatures alloys and the VSDP-4 + VSDP-23 + VTsS-4 coating applied on the intermetallic alloy.
Changes in the Specific Heat of U8 Steel after Quenching by Deforming Cutting during Its Heating to 400°C
摘要
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.
Development of the Compositions of High-Temperature Coatings with a High Emissivity Factor to Intensify Radiant Heat Exchange
摘要
Properties of the Composite Galvanic Coatings Fabricated Using the Dispersed Wastes of ShKh15 Steel
摘要
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.
Conditions of Air Shot Hardening of VT41 Titanium Alloy Blisk Blades for an Advanced Engine
摘要
The influence of the conditions of air shot hardening on the surface quality and the fatigue resistance of blisk blades made of a high-temperature VT41 titanium alloy is studied. Flat VT41 alloy samples are analyzed to determine the optimum conditions of hardening to introduce them into the process of production of welded blisks for a high-pressure compressor (HPC) in an advanced engine. The required quality parameters of the surface layers in the samples and blades after hardening, namely, residual stresses, the degree and depth of hardening, microstructural characteristics, surface roughness, are achieved.
High-Temperature Interaction in the ZrSi2–ZrSiO4 System and Its Mechanism
摘要
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.
Resource Saving
Technology of Melting an Invar in an Induction Furnace
摘要
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.
Problems of Economics
Comparison of the Indices of Strategic Competitive Initiatives of the Russian Banking and Metallurgical Business under Modern Global Economic Recession Conditions
摘要
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.