卷 63, 编号 3-4 (2019)

Data analysis has been performed concerning the limiting values of heat losses in the cooling system and consumption of coke to compensate for them in the blast furnaces, depending on their volume, technical condition, and smelting technology. It was shown that the consumption of coke to compensate for heat losses may vary from 10 to 55 kg of coke or more per ton of cast iron.

We study the efficiency of application of a system of soft reduction in the process of crystallization of a continuously cast slab (ССS) on the installation for continuous casting of steel at the “MMC” PJSC by comparing the macrostructures of ССS for different pipe steels obtained by applying the system of soft reduction and without it. On the basis of the results of normative assessment of the level of axial liquation in the slabs, we revealed a decrease in the chemical inhomogeneity in the axial zone after soft reduction. The influence of soft reduction on the structure and mechanical properties of rolled sheet is demonstrated. This influence leads to a decrease in segregation in hot-rolled products. We also established the characteristics of quality of the rolled products whose dependence on the presence of macrodefects in the structure of CCS is especially pronounced, as well as their changes caused by the soft reduction of slabs.

The development of automation and microcontroller equipment allows software implementation and industrial application of adaptive and optimal control systems. The issue of tuning the PI controllers of the zones of a furnace for heating steel before rolling at the Oskol Electrometallurgical Plant is resolved. The tuning of the PI controllers is described, and the choice of an adaptive control system based on a switching table is justified. The adaptive system allows improving the quality of control and keeping the temperature within the required operating range.

Possibilities and conditions are studied for preparing cold-rolled batch annealed steels of different strength classes from one chemical composition of ultra-low carbon IF-, IF-HS-steels using cassette technology and annealing in bell furnaces. Regimes and parameters are developed for laboratory modeling of rolled product batch annealing with substantiation of heating and slow cooling schemes. Coldrolled products are obtained with both a low yield strength (below σ_T ≤ 170–180 MPa) and strength class 180 using IF-steels of one chemical composition, in the majority of cases having a relative elongation of more than 50%. Prospects are established of using batch annealing in bell furnaces for production, including cassette technology, of high-quality cold-rolled steel from IF-HS-steels of different strength classes.

On the basis of results of modelling [1] a series of experiments is conducted for electron beam treatment (EBT) of titanium alloy VT6, VT20, VT22, and VT3-1 ingots 400 and 600 mm in diameter. As a result of this work parameters are established for titanium alloy ingot EBT making it possible to remove surface defects effectively with retention of the chemical composition of the melted layer at the level of standard specifications providing good surface quality and an increase in the yield of finished metal by up to 6%.

The article provides results of production process development for titanium-containing coating deposition by diffusion sintering of metal pastes in vacuum. Coating preparation on steel 20 specimens is studied. A paste is applied to specimens by a screen printing scheme in order to stabilize applied layer thickness. Diffusion sintering of a metal coating in a vacuum furnace is conducted at three different temperatures: 800, 1000, and 1200 °C. The distribution and variation of the number of chemical elements and microhardness values in an applied coating, the diffusion (transition) zone, and the base metal is studied. The change in the phase composition of a titanium-containing coating at a surface is determined.

We discuss various charging systems for blast-furnace operations with and without injection of pulverized coal fuel (PCF) into the hearth. We also perform a mathematical simulation of the radial distribution of coke in ore charges and analyze production data on the variation in furnace-gas temperature at the burden surface across the top throat in different charging systems. An efficient blast-furnace charging system has been developed for use when pulverized coal fuel is injected into the hearth.

The arc efficiency and specific power consumption were calculated and analyzed for the small (1.5 to 20 tons) and large (100 to 120 tons) capacity electric arc furnaces. In the small-capacity furnaces, the increased specific power consumption for melting the furnace charge (475 to 500 kW · h/t) is associated with low arc efficiency (0.55 to 0.57). In the large-capacity furnaces, the arc efficiency is 0.78 to 0.8 and specific power consumption is 360 to 375 kW · h/t.

The methods of optical and electron microscopies are used to estimate the degree of contamination of D carbon steel with nonmetallic inclusions in samples taken in all stages of steelmaking at the electrosmelting workshop of the Volzhskii Piping Factory. The procedure of smelting was carried out by using the following technology: production of semifinished products in the electric arc furnace → processing of the melt in devices for out-of-furnace treatment → continuous casting. We determine the degree of contamination of steel and the chemical composition of nonmetallic inclusions in the samples for two different procedures of deoxidation: with the AB-87 aluminum and CaC₂ deoxidizers. It is shown that calcium carbide positively affects the chemical composition of steel and the process of formation of nonmetallic inclusions and leads to the modification of corundum inclusions, and their globularization in the initial stages of steelmaking. The favorable shape of the inclusions formed in the initial stages of the out-of-furnace treatment is preserved in the subsequent stages, which facilitates their efficient removal. The application of CaC₂ as a deoxidizer makes it possible to produce continuously casted billets with a twice lower degree of contamination with nonmetallic inclusions.

The influence of sheet microstructure formed by various thermomechanical processing schedules on sulfide stress cracking (SSC) resistance under uniaxial tension for low-alloy pipe steels grades X42–X65 is studied. A favorable role is established for substitution of a ferritic-pearlitic by a ferritic-bainitic microstructure and improvement of structural component dispersion is established. The favorable effect is facilitated by using high intensity post-deformation cooling from the austenite region. It is shown that segregation bands and non-metallic inclusions in a sheet axial zone do not affect the duration of specimens withstanding SSC, but they can lead to formation of hydrogen cracks (HIC) on a specimen surface that is a defective feature. In order to prevent crack formation in a specimen surface and premature failure it is necessary to lay down high specifications for specimen gauge length and fillet surface quality.

The article is devoted to studying synthesis of magnesium master alloys with neodymium for smelting ferrous and nonferrous metals. A salt composition is selected based on analysis of composition diagrams and flux requirements for melting magnesium alloys. Differential thermal analysis (DTA) is used to determine temperature ranges of thermal effects during melting components of a salt mixture KCl–NaCl–CaCl₂ –MgCl₂ –CaF₂ –NdF₃ and during reduction of neodymium compounds by magnesium. The result is a series of experimental melts revealing the main features of magnesium-neodymium master alloy synthesis, and the main factors of the metallothermal process affecting the degree of neodymium recovery. Metallographic study of the resulting magnesium-neodymium master alloys shows that a sample consists of colonies of Mg + Mg₁₂Nd eutectic composition located at the boundaries of α –Mg dendrite cells. The method proposed for recovering neodymium from fluoride-chloride melts provides up to 99.6% extraction of neodymium.

This article considers features of the material structure of high-strength alloy VZhL21 obtained by selective laser melting (SLM) in different stages of its post-treatment. On the basis of analyzing the microstructure the so-called “process window” that is the interval of volumetric energy density for effective variation of (SLM) parameters during preparation of this material is determined. A study of synthesized VZhL21 alloy material is conducted by transmission microscopy with analysis of phase components and alloying element distribution within the volume of material. The efficiency of vacuum-heat and gasostatic treatment regimes is evaluated during crack healing. The structure of the material obtained is studied by light, scanning, and transmission microscopy after vacuum-heat, gasostatic, and heat treatment. The main structural components are determined by XPA.

The fifth author’s name should read V. O. Kharlamov.