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卷 46, 编号 11 (2016)
- 年: 2016
- 文章: 13
- URL: https://journals.rcsi.science/0967-0912/issue/view/11141
Article
New applications of compacted steel strands and wire rope
摘要
Compacted steel strands and wire rope, characterized by high structural density, elevated fracture and fatigue strength, and high wear resistance, are widely used: in river and sea transport, in manufacturing, in construction, in oil and gas extraction, in metallurgy, in the coal industry, and elsewhere. If the properties of compacted steel strands and wire rope are improved by densely packing the cross section with metal, they may be used as lightning protectors and cables in high-temperature overhead power lines, as confirmed in tests approximating practical conditions. Computer simulation significantly facilitates the selection of optimal design and manufacturing characteristics for the compacted steel strands and wire rope and also the prediction of their performance.
757-763
Coal gasification in a system with a damped circulating fluidized bed
摘要
Experiments are conducted on the steam gasification of Borodino coal in a two-chamber gas generator. The generator is based on a circulating fluidized bed with damping of gas motion by the packing. The mean size of the coal particles is 0.2 mm. Heat from the combustion chamber is sent to the gasification chamber by the circulation of a disperse powder (electrocorundum) between the chambers. The chambers are filled with spherical packing (diameter 50 mm, porosity 0.5). The size of the electrocorundum particles is 0.3 mm. The heat of combustion of the gasification products is 8195 kJ/m3. The unburned residue is 5% in chemical terms and 2% in mechanical terms. The model proposed for the gas generator consists of one heat-balance equation each for the combustion and gasification chambers. The model is consistent with the experimental data. On the basis of the model, the optimal generator parameters are found: temperature 900°C in the gasification chamber and 1020°C in the combustion chamber; proportion of coal sent to the gasification chamber 36%; chemical efficiency 40%.
764-770
Improving the production of pipe steel
摘要
Melts of pipe steel (strength class K52) obtained at the casting and rolling complex of AO OMK (a branch of AO OMK-Stal’) are analyzed. The initial data correspond to a set of 30 melts. The production system includes batch preparation, steel production in an arc furnace, treatment in a ladle–furnace unit, vacuum treatment (with microalloying and modification), hot rolling, and cutting of the rolled steel into sheet and strip. The basic factors affecting steel quality are identified. The rejection of the steel produced is mainly due to brittle and undeformable nonmetallic silicate inclusions. Changes in the process so as to reduce the content of nonmetallic silicate inclusions are recommended.
771-775
Geometry of steel sheet in a seven-roller straightening machine
摘要
A method of determining the parameters of preliminary cold straightening of steel sheet on a seven-roller machine is proposed. The calculations permit the determination of the shape and curvature of the sheet’s central plane during and after straightening, as a function of the radius and spacing of the rollers, the reduction of the sheet by the upper rollers, the sheet thickness, and also the Young’s modulus, yield point, and hardening modulus of the steel. The results may be used at steel plants in the production of broad sheet and thick-walled pipe for pipelines.
776-780
Composition of C–Si–Mn–Cr–W–V powder wire and quality of surfacing
摘要
The influence of the composition of powder wire on the properties of the applied layer on steel samples is studied in the laboratory. If amorphous graphite in 35V9Kh3SF powder wire is replaced by material containing carbon and fluorine, the porosity of the applied layer is reduced, and fewer nonmetallic inclusions (including row oxide inclusions and undeformable silicates) are present. Statistical analysis of the experimental data illustrates the influence of the carbon equivalent of the 35V9Kh3SF powder wire on the hardness of the applied layer (including the mean surface hardness and the microhardness of martensite). With increase in the carbon equivalent calculated by the Paton Institute’s formula, the hardness of the applied layer linearly increases.
781-787
Evaporation of reaction-zone components in the low-temperature plasma treatment of chromium-bearing melts
摘要
The evaporation of iron, Fe–Cr, Fe–Ni, and Fe–Cr–Ni melts at the plasma spot in treatment by low-temperature argon plasma is studied. Experiments with different masses of metal and with variation in arc power of the plasmatron are conducted so as to determine the conditions corresponding to stable surface temperature of the metal. The results show that, for experiments in which the plasma flux completely exposes the surface of the metal droplet, arc power no less than 2.0 kW is optimal; the mass of the metal should be 5‒10 g. The evaporation process is studied as function of the melt composition, and the evaporation rates are determined. Of the alloys considered, Fe–Cr–Ni melt is characterized by the highest evaporation rate in the neutral atmosphere of a laboratory plasma furnace. The surface temperature of the melt is determined indirectly, on the basis of the evaporation rate. The surface temperature of the plasma-treated melt is found to vary in the range 1950–2100 K with variation in arc power from 1.6 to 2.4 kW.
788-791
Strong bimetallic structural material alloyed with nitrogen
摘要
The production of strong two-layer steel sheet—a bimetallic structure with a basic layer of low-carbon manganese microalloyed bainitic steel and an applied layer of two-phase austenite–ferrite stainless steel alloyed with nitrogen—is considered. In trials, the production of bimetallic material on the basis of the electrical-arc surfacing is investigated: specifically, the application of high-alloy steel to a plane microalloyed steel blank, by means of welding wire (under a flux layer), with subsequent hot deformation. The trials include the simulation of forced sheet cooling on the exit conveyer of the broad-strip mill and slow cooling of the final coiled strip. The microstructure, mechanical strength, and corrosion resistance of the bimetallic structural material are investigated. The proposed material matches the corrosion resistance of existing bimetals. Its yield point and the adhesive strength of the two layers exceed those of traditional two-layer steel by at least 30–50% and are three times the standard requirements.
792-797
Blast-furnace dynamics and the static pressure losses
摘要
In the interaction of the forces responsible for the motion of batch and gases, account must be taken not only of the gravitational force on the batch column but also of the gravitational force on the gases. Accordingly, the difference in the work of the gravitational forces on fluxes corresponding to the lower and upper pressure losses must be determined. The work increases with increase in gas pressure in the furnace. Consequently, the pressure losses increase without preventing the intensification of the blast-furnace process.
798-804
Influence of rare-earth modification on the formation of nonmetallic inclusions in high-carbon steel
摘要
The content of nonmetallic inclusions when rail and wheel steel is produced by intensive modern technology and modified by rare-earth metals is analyzed. The composition, morphology, dimensions, and distribution of the inclusions in the steel are determined in the case without oxidation by aluminum or treatment by silicocalcium and also with treatment of aluminum-bearing steel by both rare-earth metals and silicocalcium. Modification with rare-earth metals reduces the content of oxide inclusions in the rail and wheel steel. That improves the plasticity and impact strength of the products.
805-813
Calculations of manganese ferroalloys production efficiency from different ores
摘要
The cost of producing manganese alloys by reduction from manganese ore using carbothermic process is estimated. Alternatives of FeMn78 and SiMn17 production from rich Australian manganese ore with low-phosphorus concentration or low-phosphorus manganese slag in charge mixture with poor domestic Russian ore with comparatively high phosphorus content are calculated and presented in the article. Direct production costs for alternative variants in a wide range of cherge composition are estimated.
814-817
Change in the surface oxide layer of piercing-mill mandrels over time
摘要
Satisfactory development of the internal and external oxide layers on piercing-mill mandrels may be ensured by annealing. In addition, strong adhesion of the layers with the metal base is observed. In electron- microscope images, the structure of the boundary layer at the metal surface is seen. It resembles stalagmites. This layer consists of metal oxides, with chaotically distributed particles of the oxides of iron, nickel, and other alloying elements. With increase in the number of piercing cycles, the oxide layer becomes thicker, and its phase composition changes. With high temperature and cooling conditions, the content of wustite FeO in the surface oxide layer increases to 80%.
818-822
Influence of peritectic transformation on the hardening, structure, and properties of steel castings
摘要
The influence of peritectic transformation on the deposition of solid phase over the cross section of pearlitic steel ingots with 0.2–0.4% C is studied. To prevent structural and chemical microheterogeneity, measures ensuring dense and uniform metal over the casting cross section are proposed.
823-829
Erratum
Erratum to: “Strategic risk management in innovative metallurgical investment”
830-830