Том 60, № 7-8 (2016)

Results are given for calculation of blast furnace operation with a high proportion of Sokolovo-Sarbaiskii Metallurgical Production Association unfluxed pellets with a different content of local agglomerate. It is shown that with an increase in the proportion of unfluxed pellets (up to 60%) in a loading charge in order to achieve the required blast furnace slag basicity charging limestone into the furnace is necessary. In order to reduce the weight of loaded “raw” limestone, it is necessary to produce agglomerate with high basicity. As the proportion of pellets increases in a loaded charge, there is a reduction in blast furnace slag magnesia content. In order to increase slag magnesium oxide concentration, it is expedient during agglomerate preparation to use a combined basic flux consisting of 70% normal and 30% dolomitized limestone.

A mechanism is provided for interaction of metal oxides with carbon. As in solid fuel combustion, this reaction is a complex multistage process with participation of atomic oxygen. The mechanism of metal reduction in its initial stages includes chemical reactions coupled with each other. It is shown that the mutual effect of these reactions increases with an increase in reagent surface contact and the proportion of the carbon oxidation reaction by atomic oxygen. Prospects for producing siliceous ferroalloys from a briquetted charge are given in the work.

The balance of zinc and lead is calculated during steel smelting in an electric arc furnace (EAF). It is shown that the main proportion of zinc and lead is removed from metal during charge melting in an EAF, and the remaining amount evaporates during steel degassing. With an increase in the proportion of galvanized steel in a charge, dust formation and zinc and lead contents in EAF discharges increase considerably. In order to determine a strategy for treating zinc-containing dust, it is necessary to monitor its content in all production stages.

In the steel production at the Severstal Cherepovets Metallurgical Combine, we conducted pilot tests of equipment and technology in the continuous casting and simultaneous application of slag-forming mixtures and inoculators as a fraction. We observed improvement in the macrostructure in the axial zone of the ingot as a consequence of a more intensive cooling, as well as by increasing the number of crystallization sites. As an alternative to the method of introducing discrete inoculators, we propose a method and develop equipment designed to deliver a continuous ribbon chiller in the mold of the continuous caster. We determine the main parameters of the equipment and technology for introducing the ribbon into the mold of the continuous caster.

This article concerns the development of an energy-efficient technology for rolling one of the most complex (from the standpoint of plastic strain) rail profiles – the grooved tramrail. A new technology which makes efficient use of the roll forces in the horizon plane is proposed. This technology makes it possible to obtain a balanced four-roll pass with equality of the roll forces that are due to compression by the vertical rollers. The results of computer modeling and a full-scale experiment with evaluation of the stress and strain intensity distributions and the roll forces in four-roll rail passes are presented. Plots of the distribution of the roll forces due to the vertical rollers are obtained and the mathematical relations for finding them are determined. The adequacy of the mathematical modeling is evaluated by comparing the obtained data and the full-scale results.

Surface defects of special alloy steel round bar of different grades, reasons for their occurrence and degree of influence with a change in microstructure on the capacity for cold upsetting according to groups 66 and 66T by GOST 10702–78 are studied. It is established that necessary conditions for obtaining positive test results for cold upsetting are simultaneous preparation of a favorable granular pearlite microstructure and the absence of round bar surface defects more than 100 μm deep. The absence of surface defects with an unfavorable microstructure does not guarantee positive test results.

Technology is analyzed for asymmetric rolling in order to improve rolled strip precision in large units: a 1700 strip cold rolling mill and a Severstal Cherepovets Metallurgical Combine 2000 broad-strip mill; in an ArcelorMittal Temirtau (Kazakhstan) 1700 continuous broad-strip mill. Research demonstrates the efficiency of asymmetric rolling for improving rolled strip precision. In the ArcelorMittal Temirtau 1700 broad-strip mill with asymmetric rolling of strip 2.0–3.0 mm thick non-flatness is reduced on average by 31% compared with symmetrical rolling. Trials of asymmetric strip rolling of corrosion resistant steel 12Kh18N10T in a Chelyabinsk Metallurgical Combine 500/1500×1700 reversing four-roll mill demonstrate the possibility of cold strip rolling with standard flatness with mill adjustment for peripheral speed mismatch of the upper and lower working rolls per pass by 2–7% and simultaneous excess of forward tension over the back tension by 3–7%.

Comparative analysis is provided for features of structure and phase composition formation, hardness, roughness, and wear resistance of die steel 4Kh5MFS surface treated with a high-temperature pulsed plasma and laser radiation. It is established that after plasma treatment surface roughness Ra was 0.42–0.78 μm, and after laser treatment it was 1–1.17 μm. It is shown that after plasma treatment surface wear resistance is better than after laser treatment. Plasma treatment makes it possible to obtain surface hardness of the order of 840 HV that is 10% higher than after laser treatment. The data obtained indicate that pulsed sources of high-temperature plasma based on plasma accelerators may be considered as a promising tool for forming improved operating properties for a die steel 4Kh5MFS surface.

The field of application is given for binary copper–phosphorus alloys in the metallurgical industry. Features of copper–phosphorus alloy structure are described. Binary copper–phosphorus solders produced in Russia and abroad are analyzed. Processing properties are provided for binary copper–phosphorus solders in relation to phosphorus content. Features of soldering with binary copper–phosphorus solders are provided. Characteristics of copper–phosphorus solder manufacture by domestic producers in the form of ribbon, bar, and wire are given. It is shown that during hot extrusion of copper–phosphorus alloys they develop superplastic flow. A mechanism is described for increasing the ductility of some copper–phosphorus alloys after thorough hot extrusion.

Results of Deform 2D simulation of and experiments on the extrusion of aluminum-alloy tubes with piercing stub mandrels are discussed. The effect of the cone angle and the mandrel position relative to the parallel land of the die on the compressive force and strain intensity is evaluated using an experimental design and a coordinate grid. A method for optimizing the geometry of piercing stub mandrels is proposed.

We examine the results of the industrial implementation and operational experience of small ignition furnaces in sinter machines of various domestic and foreign enterprises. The furnaces are equipped with automatic thermal management systems. We assess the use of hot air both as input into the burners, as well as blown into the cake layer beyond the furnace. It is shown that the sintering gas recirculation, recovered after the vacuum chamber, can significantly reduce emissions into the atmosphere, reduce the consumption of solid fuels and the mass fraction of minutiae in the final agglomerate. We study different variants of organizing the recycling of sintering gas.

Published experimental data about steel forging ingot chemical inhomogeneity with different steel weight and composition are summarized. An equation is obtained for calculating the carbon liquation factor over an ingot cross section in relation to weight and configuration (H/D ratio), and also on original carbon and sulfur content in cast steel.

Theoretical and experimental study is carried out to establish features of all types of excessive phase precipitation in low-carbon steels microalloyed with titanium and molybdenum. It is established that the main type of precipitates controlling grain boundary and precipitation hardening mechanisms is FCCcarbide based on TiC. The optimum thermal deformation treatment regime is established providing simultaneously effective grain refi nement of steel structure and the formation of a system of nanosize carbide precipitates that control strengthening by a precipitation hardening mechanism. On the basis of the results obtained, chemical composition and heat-treatment regime are proposed for producing low-carbon TiM–Mo microalloyed steels with a ferritic microstructure and set of mechanical (tensile strength more than 850 MPa) and other service properties.

Features of the effect of both individual and combined alloying with nitrogen, molybdenum and silicon of unstabilized cold-worked and heat-treated austenitic Cr–Ni and Cr–Mn–Ni steels on pitting and intercrystalline corrosion (ICC) resistance in weakly oxidizing media are studied. On the basis of corrosion and electrochemical test results (electrochemical method), an ambiguous effect of alloying cold worked Cr–Mn–Ni steels with nitrogen and molybdenum on pitting corrosion resistance is revealed. It is established that a necessary condition for intergranular corrosion resistance of chromium-nickel steels after prolonged tempering at 550–750°C is the presence of silicon in addition to nitrogen and molybdenum, which participates in improving the passivity of chromium-depleted boundary zones. Silicon added to nitrogen-containing steel alloyed with molybdenum and 0.03 wt.% carbon with a balanced content of Cr, N, Mo and Si facilitates an improvement of passivity for boundary zones impoverished in chromium. Introduction of silicon into nitrogen-containing chromium-nickel steel (0.03% C) alloyed with molybdenum with a balanced content of Cr, Ni, Mo, and Si makes its ICC resistance equal to specially low-alloy stainless steel containing 0.003% C.

Mechanical properties of steel 30KhGSA and new domestic steel B1700 specimens cut from agricultural equipment components after field trials are determined. A different wear mechanism is revealed for the steels: elastoplastic deformation with plastic repulsion of metal by soil particles and traces of microcutting of steel 30KhGSA chisels, adhesive-fatigue failure with traces of shallow pitting of a surface layer, and indentation of abrasive particles for a steel B1700 chisel. Use of the test steel makes it possible to increase soil tillage depth from 17–19 to 20–22 cm, which significantly increases the quality of agricultural operations or permits an increase in soil tillage rate.

Results are given for research to develop scientifically based process solutions to improve quality characteristics of rolled coils cooled in a two-stage Stelmor line ensuring effective metal microstructure and processing properties for wire and wire products. An increase in welding rod ductility is achieved by limiting the steel’s strengthening element content, effective application of the boron to nitrogen ratio, and optimization of two-stage cooling, ensuring the formation of large ferrite grain size with rolling heat during isothermal soaking, thereby minimizing the formation of non-ductile structural components (bainite and martensite). For high-carbon wire rod used in the manufacture of concrete sleepers, it is necessary to achieve the fine pearlite structure of point 1 (GOST 8233–56) that is provided by alloying steel with boron, vanadium, and/or chromium, and also use of fan cooling. This structure is the optimum from the point of view of metal ductility and strength.

Research results are used to confirm the compatibility of workable chromium martensitic steels alloyed with nitrogen for a cladding layer and low-alloy steels as the base layer in producing two-layer sheets by explosion welding. Satisfactory results are obtained in bend tests for bimetal steel samples that together with the results of metallographic analysis and ultrasonic testing confirm the workability of the martensitic steels developed and alloyed with nitrogen for preparing two-layer steels by explosion welding.

Results are given for comprehensive research concerning fields of metallurgy, nanomaterials, and ecology. Taking account of theoretical concepts and known practice of modifying gray cast iron, a new ultrafine modifier is considered containing carbon with increased chemical activity. It is established that carbon foam, electrolyzer dust from electric filters, and alumina passing through a dry gas cleaning system, have carbon nanostructures in their composition. Raw material composition for preparing modifying additive, procedures, and experimental materials are provided. Results are given from a series of cast iron melts with a different modifier content and a method for adding it with replacement of 50% of standard metallurgical graphite by the carbon-containing part of carbon foam. The effect of modifier on phase formation during gray cast iron solidification by means of cooling from a liquid condition is considered. A test cast iron sample and reference cast iron are analyzed chemically, and mechanical properties are analyzed. It is established that a modifier makes it possible to improve gray cast iron grade. Theories are proposed for carbon nanotube formation during aluminum production. A technology is provided for extracting carbon structures from starting raw material. It is shown that with preparation of one ton of aluminum using the production solutions developed for decontamination and utilization of industrial waste it is possible to produce modifier based on highly organized carbon nanostructures.

One of the main tasks of steelmaking is to obtain the necessary thermodynamic conditions that ensure fine and homogeneous solidified microstructure. The relatively economical solution is to feed microadditives into liquid steel. The metallurgical considerations and techniques on the feeding of microadditives are described in the present work. The effect of small addition of reactive fine particles and ultra-high melting point powders on the control of non-metallic inclusions, slab center segregation, and mechanical properties, especially the Z-direction properties, was investigated. The results showed that the microadditives had composite effects on microalloying and modification of inclusions. The segregation of elements in the slab center of high strength steels was remarkably reduced. The mechanical property along the Z-direction of steel plates was greatly improved.