卷 60, 编号 11-12 (2017)

Combined hydroforming and blanking is simulated. The use of two fracture models is analyzed. Results of field experiments conducted to validate the simulation are presented. It is concluded that the ductile fracture model is appropriate for the simulation of blanking.

Prospects of roll-forming are analyzed. Requirements to the computer-aided design (CAD) of roll-forming equipment and tools are formulated. The CAD system developed by the MISiS is described.

Results are given for the reconstruction and modernization of sintering machine AKM-312/336 No. 7 of ArcelorMittal Temirtau (formerly Karaganda Metallurgical Combine). The gas exhaust conduit of the sinter machine is reconstructed: the first stage of the gas cleaning system within the composition of the “dirty gas” collector, 28 TsN-15 cyclones and two scraper conveyers are dismantled, and the “semiclean gas” collector with 32 dust chambers and two gate valves have been replaced, beneath which a rubber conveyer has been installed. The following have been modernized: a charge drum-mixer, two charge drum pelletizers, a charge loading assembly for the sinter machine, an ignition hearth, and an assembly for charging sinter into a linear cooler. A planned number of multicyclones (from 780 to 960) of two battery cyclones is restored, and a “zero” vacuum chamber is installed beneath the ignition hearth. Stationary throttling devices are mounted within connections of the “zero” and first vacuum chambers. The first batch of massive self-cleaning grates is manufactured and tested instead of the existing light grate bars. As a result of reconstruction and modernization, the sinter machine operating area is increased from 336 to 348 m², the charge layer from 380 to 450 mm, and sinter specific productivity is increased by ~40%; gas consumption is reduced by 70%, solid fuel consumption by 7% compared with other sinter machines.

Preparation of hollow and shaped billets using electroslag remelting (ESR) technology is a promising direction for preparatory manufacture of objects for thermal and atomic power generation, petrochemistry, engineering, and other branches of industry. One of the main factors of ESR determining metal quality is deoxidation and slag regime characteristics. Optimization of slag chemical composition choice of the type and consumption of deoxidizing agent are provided in laboratory experimental melts for solid and hollow ingots of high-chromium heat-resistant steel 10Kh9MFB-Sh. NPO TsNIITMASh together with Energomash (Chekhov) – ChZEM have developed a technology for producing high-quality shaped billets of a shut-off control fitting by ESR of steel 10Kh9MFB-Sh. Laboratory and pilot plant metal structures and properties are studied.

Features of the formation and evolution of nanosize carbonitride precipitates and their effect on the microstructure and mechanical properties of cold-rolled product of medium-carbon steels microalloyed (stabilizing) with titanium of an industrial melt with a different carbon content are studied. It is established that precipitates have a complex (Ti,Nb)C composition, there is almost no nitrogen within them, although Nb is present in spite of its low (impurity) content in the steel. Precipitate size increases with an increase in temperature, annealing duration, and carbon content in steel. It is shown that during annealing in bell furnaces the structure and properties of rolled product are determined by the action of three main factors: occurrence of primary and selective recrystallization, with a direct and indirect (by delaying recrystallization) effect of nanosize carbide precipitates, and also the degree of reduction during skin rolling. During annealing of test steel cold-rolled product in bell furnaces, it is possible to achieve a unique set of mechanical properties that are difficult to combine: a prescribed low value of yield and ultimate strength ratio (0.60–0.75) with relative reduction of area of 30%, which is important for manufacturing complex shape components by efficient forging methods and deep drawing. Optimum values of annealing and skin rolling parameters providing preparation of these mechanical properties are determined.

The bearing assemblies of the work rolls of high-speed cold-rolling mills are the most heavily loaded components of the working stands. The short service life of the rolling bearings is due to overheating. It is shown that it is possible to eliminate this disadvantage of rolling bearings either by providing, based on the developed thermal model, the appropriate oil-feed cycle in the oil–air lubrication system or by selecting, using the proposed method, the viscosity grade of the mineral oil that minimizes the temperature of the lubricating film in the contact zone.

Autoclave breakdown of black shale ore without adding oxidizing agent is considered. It is demonstrated by experiment that for total breakdown of ore and vanadium oxidation in an autoclave prior ore treatment is required under atmospheric conditions. IR-spectroscopic analysis shows that under atmospheric conditions CH-groups present in the ore break down and in an autoclave there is breakdown of vanadium minerals. Optimum parameters are established for autoclave leaching of black shale ore of the Balasauskandyk deposit: temperature 140°C, sulfuric acid concentration 150 g/liter, time 2 h. The degree of vanadium leaching is 90%.

Technology is provided for preparing by surfacing followed by hot rolling of bimetallic structural materials (BSM) with a main layer of low-carbon manganese low-alloy steel of the bainitic class and a corrosionresistant cladding layer of two-phase austenitic-ferritic steel (TAF steel) alloyed with nitrogen. Results are provided for microhardness measurement of different layers and corrosion tests for BSM heat treated by different regimes. It is shown that due to a concluding heat treatment, including high-temperature austenitizing followed by accelerated cooling and high-temperature tempering in chloride-containing media the cladding layer acquires pitting resistance exceeding that of steels 08Kh17N13M2T and 08Kh22N6T, and also a favorable combination of increased hardness and uniform strength for layers of different chemical composition and structural state.

The benefits and advantages of forming parts by having a moving edge during the forming operation are illustrated by using three parts as examples. The difficulties that arise with the use of this technology and ways to overcome those obstacles are discussed. Examples are also given of problems that can be resolved by using the technology.

The thermal-performance and design characteristics of modern energy-saving reheating furnaces for heating various types of metal products are presented. The furnaces developed by the VNIIMT satisfy current requirements on unit energy consumption, emissions, and the level of automation of industrial processes. The furnaces have been introduced at various plants and their operating indices have been shown to fully correspond the design data.

It is shown that preparation of silicon at high temperature from silicon-containing resources by reduction with carbon in electric-arc furnaces is accompanied by the occurrence of complex physicochemical transformations affecting the main indices of the carbothermal process, i.e., extraction during melting (ε_Si) and end product chemical composition. The expected silicon chemical composition is obtained on the basis of a mathematical model formed by means of Selektor software simulating melting the distribution of elements entering a furnace within the charge for melting products. The predicted silicon quality is confirmed by results of x-ray microanalysis. Analysis is also conducted for the effect of a different ratio of raw material (quartzite and carbon reducing agent) for components in a loaded charge on silicon extraction. The optimum charge composition is determined for end product extraction up to 81.84%.

The variational principle of minimum total power and modern computational means are used to describe the deformation of metal in and to determine the power/force conditions for rolling rails and I-beams in universal beam passes. The results are engineering formulas for designing roll passes and calculating process parameters.

Currently, good mechanical properties and a high level of thermal stability of aluminum alloy components with a composite matrix attract considerable interest for use in aerospace and automobile industries. Widespread introduction of aluminum matrix alloys with introduced solid particles of complex composition is hindered by the high production costs of preparing components and the low level of quality for the cast objects obtained. Achievement of uniform distribution of reinforcing particles within the limits of an aluminum matrix structure is one of the most important problems affecting composite material properties and quality. Questions are studied in this work of production technology for a dispersion alloy with inbuilt silicon carbide particles. A set of laboratory tests is conducted including preliminary preparation and classification of silicon carbide particles from an exhausted lining of an aluminum electrolyzer, preparation of a magnesium master alloy with introduction of particles, and preparation of objects of a composite Al–Mg–SiC alloy. Experiments are carried out with a change in SiC content from 5 to 25 wt.% and magnesium from 2 to 10 wt.%. Results of the experiments show that the technology developed is effective for preparing uniform dispersion with introduction of reinforcing particles during preliminary addition of a magnesium master alloy to molten aluminum. With an increase in amount of silicon carbide particles, a tendency is observed of an increase in strength and impact toughness of the cast billets obtained, and the beast results for ductility are achieved with a magnesium content of 7–8% and presence of 18–20% silicon carbide (SiC) particles.

Analysis is provided for known and new technology and construction of dies for molding gas-saturated powders of tungsten and carbon powder composites made on the basis of YuUrGU scientist inventions. Gas saturation of tungsten powder is connected with the unusually low bulk density equal to 0.06–0.12 of the density of pore-free tungsten, and small powder particle size within the limits of 1–3 μm. High gas saturation of powder composites based on carbon is determined by the high capacity of carbon for adsorption of gas and liquid vapor molecules at particle surfaces.

The most effective method for improving wear resistance of rapidly wearing agricultural machine components reacting under operating conditions with an abrasive soil medium is application of hard alloy coatings by surfacing. The thickness of a surfacing layer is a factor governing the operating life of these components. Production limitations exist in applying hard alloy coatings connected with a reduction in their physicomechanical properties with an increase in surfacing layer thickness. In view of this, operating properties are studied for hard alloy coatings of different thickness for soil working components. Empirical dependences are determined governing permissible values of hard alloy surfacing layer thickness on components of working elements of solid treatment equipment. An effective production method is substantiated for applying hard alloy thick layer coatings. Production and materials science recommendations are given for preparing tool components.