卷 60, 编号 9-10 (2017)

KazSilicon Metallurgical Combine is the first enterprise in the Republic of Kazakhstan to produce highpurity metallurgical silicon. The silicon is produced in a 6.7 MW electric furnace from quartz, obtained from the Sarykul’skoe deposit, and charcoal by the method of vertical directional crystallization. As a result of large fugitive emissions of process gases, the operation of the open-type electric furnace creates very difficult conditions for maintenance work. The presence of leaks and a large number of access windows promotes atmospheric air indraft into the working region of the furnace, which causes the electrodes to break down. To solve these problens, we propose using the thermal pressure head of the process gases and extracting these gases through the furnace roof by means of three gas flues, each with capacity ~25000 m³/h. To extract the process gases fl owing from the furnace through the gasket of the electrode opening, we propose using a slotted hood covering the location of the electrode entry into the furnace. A number of recommendations are also made for improving the design of the electric furnace in order to reduce heat losses and fugitive atmospheric-air indraft into the furnace, eliminate the gas release into the atmosphere in the shop and residential zone, and simplify the operation of the electrode and current-cable holders.

The VNIIMT tested a coal drying method based on a solid heat-transfer medium (for example, metal balls). This method considerably speeds up the drying process due to the large heat-transfer area between the solid medium and the small particles. This reduces the length of the drum dryer to one-half or even one-third of the original length and specific heat consumption.

On the basis of the variational principle of metal virtual stresses and flow rates in high plastic metal deformation with complex processes of hardening and softening, we propose an iterative procedure using finite-element simulation of processing metals under pressure, taking into account the heterogeneity of mechanical properties in the volume of the deformation zone. The proposed method of solving the boundary value problem increases the computational precision for the workpiece shape deformation, satisfying the condition of ideal plasticity for the material particles at any arbitrary point in time, as well as improving the accuracy of determining the field of the average normal stress in the deformation zone.

The effect of chemical composition and recrystallization annealing regimes in continuously operating units on the mechanical properties of cold-rolled product of type 08Yu steels is studied. It is established that with a sulfur content of 0.012–0.018% during hot rolling an optimum amount and size distribution of manganese sulfide particles is achieved providing the formation on them of cementite and aluminum nitride precipitates. Complex MnS-cementite particles formed in an equalization chamber of a continuously operating hot galvanizing unit facilitate an increase in formability as a result of a reduction in the degree of the difference in grain size of the microstructure and an increase in cementite distribution uniformity. Precipitation of AlN on MnS particles in the course of metal hot rolling and cooling provides more complete removal of nitrogen from solid solution, and consequently a reduction in steel tendency towards strain ageing. A significant reduction in the proportion of fine AlN particles increases the rate of cold worked metal recrystallization, and this leads to a reduction in fineness of the microstructure and a corresponding reduction in yield strength and an increase in relative elongation.

Results are given for analytical an experimental studies of the method of hydroextrusion of thick-walled tubes of medium carbon steel without a mandrel. The aim of work is to determine the operating efficiency of the method as a whole and to check its application regimes. In order to achieve this aim, examples of numerical modeling by a finite element method in an ABAQUS system are used, and also deformation of a workpiece of actual material in a test industrial unit. The effect of degree of deformation and slope of the forming tool on liquid pressure required for changing the shape of a billet is established. It is revealed that during deformation there is thinning of a hollow billet wall, and the amount of relative wall thinning depends on the degree of deformation and die conical surface angle. It is established that compressive stresses operate at the inner contour of a hollow billet, but the outer contour stresses are tensile, and the zone of increase in deformation is adjacent to the inner contour of a hollow object. It is established that the method of hydroextrusion without a mandrel is most effective for manufacturing thick-walled hollow objects with an opening 0.5 to 3.0 mm in diameter and 100–500 mm long, and an increase in productivity by a factor of 3–5 is provided compared with deep drilling processes. A feature of the method is the possibility of automatic testing of hollow objects during manufacture under the action of liquid high pressure (higher by a factor of 3–5 than with operation of these objects). The application range for the method is precise treatment of hollow billets.

Results are given for a complete processing scheme for manufacturing small diameter grinding balls of hardness groups III and IV produced from small cross-section continuously-cast carbon steel billet. The steel chemical composition and rolling and heat treatment regimes proposed have made it possible to produce balls of grinding hardness groups III and IV since the beginning of mastering ball rolling mill 30–80. Industrial tests of grinding balls 40 mm in diameter of hardness group IV performed under Southern Mining and Processing Plant conditions demonstrate that grinding efficiency of finished class size –0.074 mm is better by 3.1% higher and specific consumption of grinding balls is 8.83% lower than in the case of using grinding balls of hardness group III produced by DMKD or Azovstal Metallurgical Combine.

Especially strong aluminum alloys of experimental compositions are studied, wt.%: Al – (8.0–9.5) Zn – (1.6–2.2) Mg – (1.2–2.0) Cu – (0.08–0.15) Zr – 0.17 Sc – 0.24 Ag – (0.05–0.07) Ti – (0.03–0.04) Mn – (0.05–0.12) Fe – (0.01–0.02) Si. Heat treatment regimes are selected. The effect of alloying and artificial ageing regimes on the structure and properties of experimental alloys are determined. It is shown that especially strong alloys of the Al–Zn–Mg–Cu system after ageing by a single-stage regime (T1) exhibit maximum strength (σ_u up to 700 MPa). Two-stage softening regime of type T22 provides a high level of mechanical properties combined with satisfactory corrosion resistance.

A resource-saving technology is presented for processing up to 100% waste, including substandard material, of wrought alloy VZh175 for turbine disks. The technology has been developed in the scientific-production complex of VIAM and makes it possible the prepare alloy from waste no worse than that produced from fresh charge materials with respect to alloying content, impurities, structure, and mechanical properties. The cost is lower by 20–30% compared with that of alloy melted by industrial technology using 50% standard waste.

Diffusion processes occurring during heat treatment in composite-reinforced titanium–aluminum material welded by explosion are investigated. Values of kinetic parameters of intermetallic phase TiAl₃ formation are determined, as well as its influence on the nature of change of properties of composite material as a whole.

A new tube plugging process is described and studied on a lengthwise rolling mill installed on PRP-140 of the Sinara Pipe Plant. The deformation of a shell on a plug in a lengthwise rolling mill is studied using the finite-element method. The behavior of the dimensionless parameters characterizing the deformation of the metal in the groove tapers with variation in the elongation ratio of the shell is established. The effect of the ovality and kinematic tension of the shell on its deformation during plugging is analyzed through computer-aided simulation. It is established that applying kinematic tension and preovalization to the shell increases the elongation ratio by 37%, decreases the variation in wall thickness, and extends the range of tube grades produced with an automatic tube rolling mill.

Drying, heating, and combustion of lumps of coke in a Waelz kiln produces gases released with active combustion of carbon in the oxidizing zone in a counterflow regime with air blast entering through the kiln discharge end. Under conditions of a charged layer of lumps of coke and materials with occurrence of them at a surface from the direction of air stream supply, there is initially development of oxidation processes with significant release of heat and an increase in charge temperature. After charging, particles of solid components descend into a lower layer and a new portion of movable material is charged. There is almost no gas movement, and oxygen concentration is close to zero. As a result of this, oxidation processes within a layer slow down considerably with a reduction in heat liberated, and under conditions of a steady-state temperature regime, there is temperature equalization throughout the cross section of lumps of charge. With a limited capacity for pelletizing starting materials due to a shortage of factions less than 0.4 mm, the pelletizing time under conditions of a drum pelletizer 3 m in diameter and 6 m long is 7.4 min, with an overall path covered by particles of 103 m, and the degree of development of this process does not exceed 17.41% with a change in average granule diameter from 10.64 to 11.06 mm. With introduction into a charge composition of peat, there is an improvement of material pelletizing capacity with increased intensity of heat transfer to fired granules within a kiln and an improvement in strength properties. There is an increase in intensity of heat exchange processes in a charge layer with improvement of contacts between ore and carbon particles. On heating of ore-peat briquettes to 1000–1050°C, there is internal heating and there is an excess concentration of CO within exhaust gases in the range up to 300–320°C. The presence within the composition of heated materials of metal oxides provides development of reduction in a stream of carbon monoxide followed by oxidation (after burning carbon with gas phase oxygen). The use of these measures in implementing the Waelz process will make it possible to increase the yield of zinc oxide by 5–10% with an increase in unit productivity by 10–15% and a reduction in specific coke consumption by 5–7%.

are provided for a study of the effect of microalloying steel with niobium, titanium,, and vanadium on the level of mechanical properties and cold resistance of coiled rolled product for pipe purposes produced under conditions of the OMK-Stal casting and rolling complex (CRC). It is shown that with a standard nitrogen content in steel (less than 0.008%) under CRC conditions introduction into pipe steel of microadditions of vanadium does not provide strengthening for coiled rolled product by a precipitation hardening mechanism. Precipitation of vanadium carbide phase is difficult as a result accelerated strip cooling on the run-out table before winding strip on a coil and use of relatively low coiling temperatures under CRC conditions. Separation of VC particles after tempering at 650°C confirms retention of vanadium in solid solution. The presence of fine VN particles in steel with an increased nitrogen content may be explained by the fact the vanadium nitride phase may precipitate at higher temperatures compared with carbide. Research work has made it possible to assimilate production of cold-resistant coiled rolled product more than 10 mm thick of strength class up to K60 under CRC conditions without microalloying steel with vanadium.

A procedure is described for qualitative evaluation of the effect of binders on granulated slag-forming mixture (SFM) strength. A relationship is established for slip density and finished granulate bulk density on water content. Industrial tests are conducted for a new binder and a test batch of granulated SFM is prepared with a low proportion of dusty fraction for pouring steel in a CBCM at MMK.

The change in mechanical properties and shape parameters is studied for pipe with high deformation capacity (HDC) 1420 × 21.7 mm in size of strength class K60 during cold bend manufacture with a reduction in bend radius. Features are demonstrated of steel structure of HDC pipes providing ageing resistance and improved deformation capacity, including presence of MA component and polygonal ferrite in a bainitic matrix. The use of HDC pipes will make it possible to prepare bent sections with a radius reduced to R ≈ 20D_o without corrugation formation and with geometric parameters within the framework of specifications for “standard” bends. Thermal action during application of an anticorrosion coating (200–250°C) leads to an increase in strength, especially σ_y(Rt_0.5) and the ratio σ_y(Rt_0.5)/σ_u in the longitudinal direction and reduction in ductility (δ₅ and δ_u). However, after HDC pipe heating sufficient deformation capacity is obtained for bends. Features are determined for the change in mechanical properties and tensile curves for steel in zones subjected to tension (TZ) and compression (CZ) during pipe bending with residual plastic deformation up to ~3%. For TZ and CZ metal, there is a different direction of the change in σ_y and σ_y/σ_u in the longitudinal direction, and also a reduction in ductility indices (δ₅ and δ_u) in transverse and longitudinal directions. The production limitations revealed during pipe bending arising due to the danger of jamming of a mandrel in a pipe during bending are revealed.

The causes of cone formation on the face of carbon anodes in aluminum electrolyzers are examined. The mechanism of cone formation has not been studied well enough to reduce the coning frequency in practice. In addition, many scientists and experts believe that work on the development and implementation of measures for the prevention of cones is economically inefficient. Data on two fundamental mechanisms of cone formation have now been published: carbon reduction on the anode face and individual sections of the anode falling behind in oxidation. Electrolytic reduction can be secured by bringing carbon to the surface of the anode. As a result of the appearance electrophoresis, carbon particles can move in the direction of one of the electrodes, increasing or decreasing the carbon flux.

Development of compositions and application of coatings by cold gas-dynamic deposition from powders prepared by means of a micrometallurgical method is studied. In addition, use of mechanical alloying technology is substantiated during composite powder preparation based on aluminum for creation of wearresistant coatings. Results are given for the effect of reinforcing component concentration and powder composite preparation method on the main wear-resistant coating properties for a metal–nonmetal system. Results are provided for an experimental study of adhesive strength, microhardness, porosity, and wear resistance of coatings made from powder matrix material of the Al–Sn–Zn system prepared by a micrometallurgical process of high-speed melt quenching, and also composite powder of the system Al–Sn–Zn–Al₂O₃.