Metallurgist (v.58, #11-12)

It is shown that it is possible to intensify the cleaning of emulsion- and oil-bearing waste water from rolling-mill operation. The water is given a secondary treatment in an electrical flotation unit that automatically controls current density and electrode spacing. Operating regimes for the unit are developed for the secondary cleaning of emulsion-bearing waste water from cold-rolling mills after primary cleaning in horizontal settling tanks with reagent FeCl2, a small amount of H2SO4, and spent pickling solution. The optimum regime for use of the flotation unit for the secondary cleaning of oil-bearing waste water from hot-rolling mills is determined. A cleaning level of 94–95% is achieved for waste water in which the initial content of petroleum products is 100 mg/liter.
Keywords: intensification of primary and secondary cleaning; emulsion- and oil-bearing waste water from rolling-mill operation; electroflotation

Results are presented from a theoretical study of the effect of the liquid residue in electric-arc steelmaking furnaces (EAFs) on unit electric-power consumption and the duration of the heat. Quantitative estimates are made of the heat flux which exists during the heating and melting of continuously charged small batches of scrap. In this case, the scrap is heated and melted as a result of forced convection in the liquid residue. The heat flux is also quantitatively estimated for the case when the entire scrap charge is introduced into the furnace at once and the scrap is heated and melted by radiation from the arcs in the furnace’s working space. A hypothesis is proposed to explain the existence of an optimum weight for the liquid residue in EAFs charged by different methods.
Keywords: electric-arc steelmaking furnace (EAF); liquid residue (“hot heel”); charging of an EAF

Critical Nitrogen Concentration in High-Nitrogen Steels for the Production of a Dense Ingot by A. G. Svyazhin; V. E. Bazhenov; L. M. Kaputkina; J. Siwka; V. E. Kindop (959-966).
The critical concentration of nitrogen in steel during its equilibrium crystallization is best defined as the concentration at which the nitrogen content of the remaining liquid steel does not exceed nitrogen’s solubility in the liquid at the given pressure and temperature. The critical nitrogen concentration is most expediently determined by means of the program Thermo-Calc. Calculated values of critical concentration obtained from the program should then be refined in practice for specific crystallization conditions.
Keywords: nitrogen steels; solidification; gas bubbles

This article examines the problem of efficiently determining heat transfer in the secondary cooling zone (SCZ) of a continuous caster. An analytical method is developed to solve this problem. The method is based on the notion that it is necessary for the cooling rate on each longitudinal section of the SCZ to be equal to the sum of the amount of heat released at the solidification front and heat flux corresponding to the prescribed rate of cooling of the metal that has already solidified. The accuracy of the proposed method is checked by using an adapted mathematical model of continuous steel casting that is based on a differential equation which describes nonsteady heat conduction. Results which are presented from numerical experiments show that the temperature field of the solidified part of the ingot, which conforms to the cooling rate established by using the proposed method, is characterized by a uniform decrease in temperature through the entire thickness of the ingot.
Keywords: continuous casting; secondary cooling; temperature field of an ingot; heat-transfer coefficient; mathematical modeling

Use of a Round Continuous-Cast Billet for the Production of Rolled Sections by I. I. Lube; S. A. Botnikov; V. P. Turbar (973-975).
Different methods of making rolled sections are analyzed along with the advantages and disadvantages of rolling sections from round and square continuous-cast billets. A literature search is made to find studies concerning the use of round continuous-cast semifinished products for making sections.
Keywords: round continuous-cast billet; square continuous-cast billet; continuous section caster; quality of rolled sections; total elongation ratio

Principles for creating a new generation of steels for preparation of objects by hot stamping with an improvement of strength properties (ultimate strength up to 2200 MPa) by a factor of three are analyzed. It is shown that first of all they should be aimed at simultaneous provision of good steel hot ductility indices, quenchability, and hardenability. It is established that boron-containing steels, and also steels of the alloy and microalloy systems Mn–Cr, Mn–Mo–Nb, Mn–Cr–Ni–(Mo–Nb–V) with an attempt to reduce carbon content are most promising for this purpose. With the aim of verifying results obtained experiments are performed for the effect of cooling rate on steel strength properties of the alloy systems selected. Adequacy of the main conclusions and the promise of using boron for alloying, and also alloying and microalloying additions C–Mn–Cr–Ni–Nb–V systems in order to create new low-alloy weldable steels for preparation of objects by hot stamping are confirmed.
Keywords: steels; hardened during stamping; hot ductility; hardenability; quenchability; martensitic structure; excess phase precipitation; high-strength objects

Nonmetallic Inclusions and Promising Principles for Improving the Set of Properties and Quality Characteristics of Steel by A. I. Zaitsev; I. G. Rodionova; O. N. Baklanova; A. I. Kryukova; K. A. Udod; P. A. Mishnev; A. V. Mitrofanov (983-991).
Results of a detailed study of continuously-cast low-alloy pipe steel metal demonstrate a significant difference in micro- and macrostructural states, including the presence and extent of equiaxed and columnar crystal areas in relation to the later stages of ladle treatment. A marked difference is also recorded in impact strength indices, hydrogen corrosion cracking resistance, and other service properties obtained for different rolled billets. It is established that as a result of adding large amounts of silicon- and manganese-containing ferroalloys in the later stages of ladle treatment or in the process of steel continuous casting there is formation of liquid silicate inclusions. Due to a high silica content during steel crystallization these inclusions are converted into a supercooled liquid or glassy condition and acquire irregular shape, filling the space between growing crystals. As a result of this they effectively reduce the intensity of mass- and heat-transfer during steel crystallization, block development of liquation processes, and facilitate an increase in the degree of metal structural and chemical inhomogeneity. As a consequence there is an increase by a factor of 2–2.5 in impact strength to extremely high values (KCV–40 more than 400–420 J/cm2), and rolled product hydrogen cracking resistance.
Keywords: structural steels; continuously-cast billet; rolled product; nonmetallic inclusions; glass; structure; chemical and structural inhomogeneity; liquation; impact strength; service properties

Boron-Containing Steel Structure and Properties at Room and Elevated Temperature by A. Yu. Churyumov; M. G. Khomutov; A. A. Tsar’kov; A. V. Pozdnyakov; A. N. Solonin; E. L. Mukhanov (992-997).
A Gleeble 3800 thermomechanical process physical simulator unit is used to study the structure and mechanical properties of corrosion-resistant steel with a high boron content intended for production of hexagonal pipes for exhausted nuclear fuel storage. Compression tests at room and elevated temperature show that with an increase in test temperature from 20 to 600°C yield strength and flow stress decrease by a factor of two in the steady-state stage, and over the whole test temperature range the steel demonstrates good ductility in compression. The steel’s structure does not undergo marked changes during deformation: stringing, formed during hot forging, is retained during subsequent plastic deformation.
Keywords: steel; borides; microstructure; mechanical properties

Technological Aspects of the Production of Pipes Made of Laminated Metallic Materials for the Technical Facilities of the Oil, Gas, and Chemical Industries by I. G. Rodionova; A. A. Pavlov; O. N. Baklanova; A. I. Kryukova; A. S. Mitin; A. A. Rodionov (998-1000).
Technological aspects of the fabrication of welded structures from laminated materials and distinctive features of the production of pipes from metallic laminated materials are discussed. A new technology has been developed for making welded pipes.
Keywords: metallic laminated materials; welding; hard-facing; welds; welding technology

Certain trends in the improvement of the operations that are carried out to make cold-deformed tubes are discussed and “technological niches” are identified. Mathematical modeling is performed of the operations executed in roller drawing through one and two roller dies, periodic drawing, and the nonuniform reduction of circular tubes that vary in the thickness of their wall. The modeling is done using the finite-elements method and variational methods from metal-shaping theory. The results obtained from analyzing the laws discovered during the modeling are used to develop new methods of drawing and improve the design of the equipment used on tube cold-rolling mills.
Keywords: cold-deformed tubes; cold periodic rolling of tubes; design of rolling-mill equipment

Preventing the premature wear of pump-compressor tubing (PCT) is an important problem in the Russian oil industry. This wear is caused mainly by different types of corrosion, and a new technology has been proposed to recondition damaged tubes. The technology involves lining damaged PCT with an internal thin-walled pipe made of corrosion-resistant steel, and it makes it possible to obtain composite tubes with excellent service properties. An experimental batch of lined tubes was tested under field conditions, with the results showing that the lining technology is a highly efficient means of increasing the service life of PCT.
Keywords: pump-compressor tubing; lining technology; composite tubes

Use of Mathematical Modeling in Selecting a Heat-Treatment Regime by V. V. Kotov; K. I. Sergeeva; V. A. Troyanov; S. V. Belikov (1011-1018).
Optimizing the processes used to make new and existing products is an important problem in modern industry. The urgency of this matter has led to broad use of mathematical modeling to model various industrial operations, including heat treatments. However, the adequacy of the results obtained by using the finite-elements method to model physical processes is still open to debate. The goal of this article is to evaluate results from mathematical modeling performed to choose regimes for the heat treatment of low-alloy steel and an aluminum alloy and compare those results with the results of a physical experiment.
Keywords: modeling; steel; aluminum alloy; heat treatment; structure; properties; deformation

A method is considered for panoramic crystallographic analysis of bainite and martensite structures based on images of crystal lattice curvature and making it possible to identify α-phase varieties, and also to determine their volume fraction. The method is proven successfully for high-temperature alloy steels, for which by means of dilatometry and expert evaluation of metallographic images a characteristic scale is plotted for lattice curvature, whose ranges correspond to bainite and martensite structural types.
Keywords: bainite; martensite; lattice curvature; EBSD; structural types

Developing Metallic Damping Materials by E. B. Utepov; R. S. Omirbai; D. K. Suleev; G. A. Burshukova; A. S. Berkinbaeva; A. K. Nurgaliev; G. M. Ibraeva (1025-1031).
Studies are made of the acoustic properties of metals obtained from steels 08kp, 25, and 50 and aluminum alloy AL2. New metals characterized by reduced sound radiation have been developed, and the effect of heat treatment on this property is evaluated.
Keywords: alloy; industrial noise; sound radiation; damping; metals; heat treatment

Fatigue Strength of Microalloyed Hot-Deformed Powder Steels by Yu. G. Dorofeev; V. Yu. Dorofeev; Kh. S. Kochkarova (1032-1037).
Fatigue test results are provided for hot-deformed powder steels with microadditions of Na, Ca, and Al. Microalloying promotes improvement of joining between particles and makes fatigue crack development difficult in its stable consolidation stage, and also during accelerated failure, which provides an improvement in fatigue strength properties compared with reference specimens.
Keywords: powder material; hot stamping; microalloying; iron; sodium; calcium; aluminum; durability; fatigue; failure; consolidation between particles

Change in Structure During Consolidation of Calcium Hydride Powders of TiNi Intermetallic by A. V. Kasimtsev; G. V. Markova; A. V. Shuitsev; Yu. V. Levinskii; T. A. Sviridova; A. V. Alpatov (1038-1045).
Results are provided for a study of the composition, structure, and physicochemical properties of TiNi intermetallic powder prepared by a calcium hydride method. The effect of various forms of consolidation (HIP and hydrostatic compaction followed by vacuum sintering) on the chemical and phase composition of compacts from calcium hydride powders is studied by optical and scanning electron microscopy, x-ray structural analysis, and gas-forming element analysis. A change is shown in the phase composition as a result of TiNi powder consolidation. It is established that vacuum sintering makes it possible to reduce the content of gas-forming admixtures (oxygen, nitrogen, and hydrogen).
Keywords: calcium hydride method; powder metallurgy; intermetallics; TiNi; HIP; consolidation

This article examines problems related to the quality and production of anode paste for self-baking anodes in aluminum electrolysis cells. Results are presented from laboratory tests of a technology designed to thoroughly impregnate coke dust with coal-tar pitch by giving the dust and pitch opposite electrical charges in dc chargers during the paste production process. The technology significantly improves the quality of the paste while reducing its production cost and improving the technical-economic and environmental indices of aluminum production. These benefits are realized by increasing the degree of impregnation of coke dust by coal-tar pitch, reducing the friability of the anodes during service in electrolysis cells, and decreasing the amount of coal-based foam that is formed in the process. Increasing the productivity of the equipment used to make anode paste by shortening the time needed to mix the components also lowers production costs. Environmental indices are improved by shortening the time the cell is dehermetized, thus decreasing the unit quantity of fluorides released into the atmosphere.
Keywords: anode paste; coke dust; pitch; method of producing anode paste

Choosing an Efficient Method for Forming Parts by Means of an Engineering Analysis Performed with the Use of a CAE System by A. A. Cheslavskaya; V. V. Mironenko; A. V. Kolesnikov; N. V. Maksimenko; V. V. Kotov (1051-1059).
The possibility of forming parts by different methods is analyzed. The formation of defects is modeled and ways are proposed for eliminating them. A conclusion is reached as to the most efficient method of making the part that is discussed.
Keywords: pneumo-thermal forming of sheetmetal parts; drop-hammer drawing; elastoforming; drawing in rigid dies

Developing Software for the Feed-Control Systems of High-Power Aluminum Reduction Cells by P. A. Petrov; Yu. V. Sharikov; A. A. Vlasov; V. Yu. Bazhin; A. Yu. Feoktistov (1060-1063).
The current state of systems used to control the feeding of high-power electrolysis cells is examined. The article describes the creation of feed algorithms that send a separate signal to each punch of the electrolysis bath in order to correct the feed cycles in relation to alumina dissolution rate. The corrections are made with allowance for the boundary conditions of the process parameters.
Keywords: electrolysis; algorithm; dissolution; alumina; feeding

Problems with Waste Generation and Recycling in the Ferroalloys Industry by A. V. Zhdanov; V. I. Zhuchkov; V. Ya. Dashevskii; L. I. Leont’ev (1064-1070).
The wastes generated in the production of ferroalloys are mainly in the form of slag, dust, and sludge from gas-cleaning systems, in addition to ferroalloy gas. The volumes of these waste products that are formed depend on the charge materials and manufacturing technology used at the given factory. The problem of waste formation during ferroalloys production should be regarded as a direct result of the technology chosen for the production process. Efficient resolution of the waste-recycling problem requires maximal collection and disposal of the wastes and analysis of alternative uses for them based on an accurate assessment of their physicochemical characteristics (their chemical, fractional, and mineralogical compositions, in addition to several other characteristics).
Keywords: waste from ferroalloys production; waste generation; chemical composition of waste; volumes of waste

A three-dimensional mathematical (dynamic) model is presented to describe the sintering process. The model was developed to solve theoretical and practical problems. It allows real-time determination of the dynamic distribution of the temperature and chemical composition of the charge, the melt, the sinter cake, and the gas in the bed with allowance for transients, as well as the temperatures in the pallets and the parameters of the gas flow in the flue channel – including air infiltration.
Keywords: three-dimensional (dynamic) mathematical model; sintering process; sintering machine; gas; moisture content; reduction; gas dynamics; evaporation; condensation; heating; oxidation; cooling; melting; filtration rate; temperature; fuel; chemical composition; charge

The prerequisites for maximizing the use of pulverized-coal fuel (PCF) injected into the hearth of blast furnaces are examined for the operating conditions in the blast-furnace shop at the Mariupol Metallurgical Combine The maximum possible amount of PCF that can be used is determined based on the thermal state of the furnace, its gasdynamic regime, and the durability of the lining and the coolers in the bosh. Calculations are performed using both shop performance data and results obtained by mathematical modeling.
Keywords: pulverized-coal fuel; thermal state; gas permeability; cohesion zone; combustion focal point; blast furnace; coke; pig iron; slag; gasdynamic stability

An original method is developed for predicting the temperature and concentration dependences of surface tension for molten slag of the CaO–Al2O3–CaF2 system and its subsystem components. It is based on approximating component activity within the volume and at the surface of a melt within the scope of associated solution theory. Free model parameters are established on the basis of available experimental data for thermodynamic, structure-sensitive physicochemical, including surface tension, molten slag properties. The method developed makes it possible to predict the temperature and concentration dependences of surface tension for metallurgical slags containing apart from oxides, compounds of a different nature with accuracy no worse than experimental, and it may be extended to melts of any complexity and component content. Prospects for its use are demonstrated for selecting a slag regime in various metallurgical processes.
Keywords: metallurgical slags; surface tension; oxide-fluoride melts; thermodynamic; physicochemical properties; associated solutions

Ways of Improving Stainless Steel Production Indices by Yu. A. Gudim; I. V. Fokin; I. Yu. Zinurov (1093-1097).
Possible ways are considered for improving contemporary stainless steel production indices. It is shown that the greatest improvement in stainless steel production indices may be achieved by reducing metal loss in the form of scrap and beads, and loss during metal scarfing. A reduction in losses compensating environmental damage caused by stainless steel production may also improve production indices in the near future.
Keywords: production indices; stainless steel; metal loss; scrap; slag; dust; arc furnace; argon-oxygen refining; continuous casting

Evaluation of the Effect of Aluminum Content on Steel Corrosion Resistance Indices and Specific Strength by I. G. Rodionova; O. N. Baklanova; K. A. Udod; I. B. Chudakov; N. I. Endel’; A. S. Mel’nichenko (1098-1104).
The effect of adding aluminum on steel specific strength and corrosion resistance is studied. It is established by calculation that aluminum is the most effective element for reducing steel density. The effect of aluminum content on steel specimen corrosion resistance is studied by electrochemical methods. The possibility of improving steel corrosion resistance by alloying with aluminum in an amount of 8–12% is demonstrated.
Keywords: steels; aluminum content; specific density; corrosion resistance; electrochemical methods

Different test methods are discussed for determining the mechanical properties of materials in the superplastic state. The flow stress depends on the degree and rate of deformation, a structural parameter, and temperature. The rheology and mechanics of superplastic deformation are discussed. In response to an order from the company EADS (Airbus), a new method was developed and has yielded good results in the testing of titanium alloys and the construction of mathematical models. The method, for conducting tests and then approximating materials’ mechanical properties, is of great interest for the purpose of obtaining adequate predictions of the forming of materials under pressure.
Keywords: mechanical properties of materials; superplasticity; modeling; mechanical tests

Optimization of the Technology Used to Make Polymetallic Superconducting Composites by G. L. Kolmogorov; M. V. Snigireva; E. M. Aver’yanova (1110-1117).
A method is proposed for determining the optimum parameters for drawing polymetallic bar and wire products with allowance for the sizing zone. The method makes it possible to determine the optimum parameters of the production process in the manufacture of polymetallic superconducting composites.
Keywords: drawing; polymetal; drawing angle; elongation; optimization

The various pyrometallurgical and hydrometallurgical methods that have been examined for processing ores from the Udokan deposit are not cost-effective. It is proposed that all oxidized and low-grade ores in the deposit be processed by heap leaching and that the high-grade, readily concentrated ores be processed by the traditional pyrometallurgical scheme. In addition to copper, this approach makes it possible to also produce the sulfuric acid and steam needed for heap leaching. The combination pyrometallurgical-hydrometallurgical technology provides for fuller use of the raw material and makes the production process as a whole more cost-effective.
Keywords: ore; heap leaching; extraction; cathode copper

Promising Resource Saving Technology for Processing Melts During Production of Cast Aluminum Alloys by V. B. Deev; I. F. Selyanin; A. I. Kutsenko; N. A. Belov; K. V. Ponomareva (1123-1127).
Promising resource saving technology for processing melts of cast aluminum alloys is analyzed. It is shown that implementation of technology for physical action on melts (temperature-time treatment during melting, a magnetic field during melting, an electric current during crystallization) during production of cast aluminum alloys AK7ch, AK5M2, and AM5 using an increased amount of secondary materials in a charge facilitates an improvement in metal mechanical properties in the cast condition. The effect of physical action on aluminum alloy crystallization is considered from the point of view of quantum theory.
Keywords: melt; physical action; melting; cast aluminum alloys; mechanical properties; secondary materials; crystallization; resource saving technology; magnetic field; temperature-time treatment; energy spectrum of electrons; quantum theory

Anode Mass Cover as an Aluminum Electrolyzer Subsystem by S. G. Shakhrai; P. V. Polyakov; G. V. Arkhipov; E. R. Shaidulin; A. V. Sman’ (1128-1135).
The practice of aluminum plants for creation and improvement of an anode mass cover is reviewed. Aluminum plants operating low-power electrolyzers use alumina as a cover material, exhibiting low thermal conductivity, but good gas permeability. Operation of more powerful electrolyzers requires effective anode protection from oxidation, a reduction in carbon dioxide discharge, stabilization of the bath thermal balance with a high current, and optimization of heat loss upwards through a cover. A contemporary cover consists of a mixture of crushed electrolyte and alumina in almost equal proportions, and it is an electrolyzer subsystem having a marked effect on technical and economic indices.
Keywords: aluminum electrolyzer; anode mass; cover; energy consumption