Semenov Yu. S.Horupakha V. V.Vashchenko S. V.Khudyakov A. Yu....
11页
查看更多>>摘要：An analytical method for preliminary assessment of the compactability of charges made from fine materials of the mining and smelting industry is developed. The method allows establishing the functional dependence of the density of a briquette on the applied pressure without experiments on the compression of a charge in special pressure equipment. The method involves the use of a new compaction model and the relationship between the compact density at a given pressure and the physical and mechanical properties of a charge (loose bulk density, tapped bulk density, true density of particles) for dry charges and charges mixed with water or liquid binder. The method can be used in briquette production when choosing processing modes and creating pressure equipment.
Yоlkin D. K.Karlina A. I.Sivtsov A. V.Yоlkin K. S....
8页
查看更多>>摘要：The authors analyzed data concerning the content of the starting materials and products of the intermediate reactions of silicon reduction, as well as electrical parameters of the workspace zones in the ore-reduction furnace baths. It was noted that the state of the technological process and its parameters largely depend on the content of silicon carbide in the burden and melt zones and its relationship with the silicon monoxide flow intensity. Examples illustrating negative effect of the corrective reducing additives on the technological process and furnaces performance are provided.
Babanin A. Ya.Belov B. F.Mints A. Ya.Abakumov I. A....
8页
查看更多>>摘要：Based on the conducted studies, the authors have determined the changes in the structural and chemical conditions of calcium silicates that are present in slag during steel smelting in a 120-ton electric arc furnace of the Danark system and its secondary refining in a steel-pouring ladle of the ladle-furnace unit. The following chain of calcium silicate transformations has been established:CaO·SiO2→2CaO·SiO2→3CaO·SiO2→4CaO·SiO2.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathrm{CaO}\cdotp Si{O}_2\to 2\kern0.1em CaO\cdotp Si{O}_2\to 3\kern0.1em CaO\cdotp Si{O}_2\to 4\kern0.1em CaO\cdotp Si{O}_2. $$\end{document}A method based on the theory of MHS-phases (model of harmonic structures) was used to determine the structural conditions of calcium silicates and present them in the form of structural-ionic-molecular (SIM) complexes. It was found that 4?CaO???SiO2 (eutectic) and 3?CaO???SiO2 compounds have the highest and the second highest desulfurizing abilities, respectively. The obtained results enable control of the slag activation process to significantly increase its refining capacity, as well as predict and optimize the technological parameters of steel desulfurization without the use of expensive and scarce materials.
Rodionova I. G.Amezhnov A. V.Arutyunyan N. A.Gladchenkova Yu. S....
11页
查看更多>>摘要：The effect on corrosion resistance of the structural state of cold-rolled low-carbon microalloyed steels treated in continuous annealing units was studied. The bulk density and size of niobium carbonitride nanosized precipitates were established as the main structural factors determining the corrosion resistance of rolled products. The formation of these precipitates is shown to be affected by hot rolling temperature parameters. An increase in the temperature following rolling in roughing stands, as well as at the conclusion of final rolling and coiling, contributes to a decrease in the quantity of nanosized particles and an increase in their average size in the rolled products following annealing, which increases the corrosion resistance of the steels under consideration.
Yakovleva K. Yu.Barichko B. V.Kosmatsky Ya. I.Zaselsky E. M....
7页
查看更多>>摘要：The paper considers the main aspects of designing a technology for the manufacture of seamless cold-deformed tubes made of 12Kh18N10T austenitic steel according to possible schematic diagrams of coiled tube production and actual technical solutions ensuring its rational organization under the conditions of domestic plants. A generalized method for determining the optimal drum diameter is presented along with features of calculating the main technological parameters, taking into account the actual nature of material hardening processes. An effective technology is proposed for the manufacture of coiled tubes under the operating conditions of TMK-INOX LLC, having an outer diameter of 10–25 mm, a wall thickness of 1.0–1.5 mm, and a length of at least 50 m.
Nikulina A. A.Plotnikova N. V.Kornienko E. E.Dolgova S. V....
9页
查看更多>>摘要：Results are provided for structural studies and mechanical property evaluation of surfacing layers prepared by pulsed arc surfacing with austenitic wire A7-1G on high-carbon steel é76 during production of railway crossovers. Welding and surfacing of various materials, especially if one of them has a high carbon content, is an important practical task connected with obtaining an effective surfacing layer structure and heat-affected zone. Use of light and scanning electron microscopy methods shows that pulsed arc melting makes it possible to form various austenitic and pearlitic steel compounds, and within the heat-affected zone in carbon steel a fine ferrite-pearlite mixture with a minimum ferrite grain size of 1 μm is present. Features of the ferrite formed in this case are its irregular shape, curvature, interrupted nature, and defects in the form of discontinuities. Part of the cementite undergoes transformation into granular form. These features of the heat affected zone structure are favorable from the point of view of providing the crack resistance indices required for the joints obtained. It is demonstrated that with tests by a three-point bending scheme for crossover elements the failure load increases by 15% compared with welded joints of the same steels.
查看更多>>摘要：The practice of manufacturing tungsten-containing wear-resistant steels and products made from them currently comes down to alloying iron-carbon alloys with ferrotungsten. Preparation of ferroalloys from ore concentrates is a multiple operation, energy- and material-intensive process. It is proposed to reduce production costs related to separate manufacture of ferrotungsten and iron-carbon alloys by combining the specified stages into one using metallothermy. Tungsten-containing iron-carbon alloy formation is accomplished by an exothermic reaction in specially formulated mixtures containing a reducing agent, iron oxides, and scheelite concentrate. Use of available and cheap local crude ore of complex chemical composition and metallurgical scale may give rise to an unpredictable nature of chemical reaction and also uncertainty of the final product chemical composition. In order to establish features of the effect of reducing agent and scheelite concentrate within thermite compositions on metal final yield and chemical composition of alloys prepared by metallothermy research is conducted connected with aluminothermic preparation of iron-carbon alloys containing tungsten.
Maisuradze M. V.Yudin Yu. V.Kuklina A. A.Lebedev D. I....
12页
查看更多>>摘要：Features of the microstructure formation in steel 30Cr2MnSiNi2WMo (VL-1) are studied with various heat treatment regimes: stepwise quenching at temperature below Ms (quenching and partitioning), and isothermal quenching for bainite. It is shown that the calculated optimum temperature of stepwise quenching does not provide the predicted amount of stable retained austenite in the test steel microstructure. Mechanical properties of steel 30Cr2MnSiNi2WMo after implementation of stepwise and isothermal quenching are determined. It is established that after isothermal heat treatment the steel studied exhibits reduced viscoplastic properties compared with a condition after bulk hardening and tempering.
查看更多>>摘要：Results are presented for industrial experiments on lead brass extrusion through a two-channel die with process temperature variation. Mechanical properties of the extruded products are measured. Results of processing show that the dependence of ultimate strength on extrusion temperature is extreme in value. A function minimum is observed close to 720°C, and this temperature corresponds to the phase transition point. It is also revealed that leading part of the bar has lower strength than the rear part. Metallographic studies are performed showing differences in grain sizes and phase ratios with variation in temperature and sampling locations.
NSTL
Springer Nature