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O. Yu. Sheshukov, , D. A. Lobanov
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-192-199

Abstract:
The actual problem of mineral resources depletion in ferrous metallurgy can be effectively solved by complex reuse of technogenic waste. That waste is mostly presented by EAF (electric arc furnace) slag and LF (ladle furnace) slag. These two kinds of slag have no complex full utilization. The residues of slag are going to the dump and then the slag dump locations pollute the environment. However, the residues of EAF and LF slag can be transformed into the valuable industrial product by interaction of the slag components. This work presents the research for joint wasteless processing of EAF and LF slag with production of Portland clinker and cast iron. The article describes disadvantages of known methods of each slag processing; the paper also shows the significance of LF slag utilization. Design and calculations of the research are presented as well as its experiment methodology. The final results show five chemical compositions for the mixtures, which allow the complex processing of this slag without any waste left. Such processing provides the production of cast iron and Portland clinker both meeting requirements of normative documents. The paper also describes the results of viscosity measurements of slag compositions, the obtained slag phases, and presents the final temperature conditions. The work also considers the results of industrial tests for the developed processing technology and a complete technological chain involving the use of tilt rotary furnaces.
V. I. Berdnikov, Y. A. Gudim
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-211-213

Abstract:
Моделирование химического процесса, возникающего при термическом контакте гематита с монооксидом углерода, проводили по- средством программного комплекса Терра. При этом мольное соотношение компонентов CO/Fe2O3 варьировалось в пределах 1 – 15, а температура процесса – в диапазоне 25 – 1500 °С. Монооксид углерода при обычной температуре разлагается практически полностью с образованием углерода и диоксида углерода (реакция Белла-Будуара). Этот углерод при повышении температуры процесса последовательно участвует в формировании фаз магнетита, железа и цементита, а диоксид углерода – при образовании вюстита и при обезуглероживании железа. Непосредственное участие монооксида углерода в роли реагента-восстановителя в локальных химических реакциях этого процесса не установлено.
M. V. Kostina, V. I. Krivorotov, V. S. Kostina, A. E. Kudryashov, S. O. Muradyan
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-217-229

Abstract:
Исследованы особенности химического состава и структурно-фазового состояния образцов металла стали 18Cr-10Ni (AISI 304), которые могли способствовать возникновению общего коррозионного повреждения и образованию питтингов деталей из указанной стали под воздействием агрессивной среды. Установлено, что содержание серы в стали превышает почти в 10 раз установленный стандартом на эту сталь уровень (<0,03 % S), поэтому она содержит около 3 % (об.) сульфидов марганца размером 1 – ~50 мкм, образующих строчки и скопления вдоль направления прокатки. По литературным данным, в коррозионностойких сталях и сплавах наиболее коррозионно-активны именно частицы сульфида марганца (MnS). Они многократно снижают способность Fe – Cr – Ni сталей к пассивации в коррозионной среде. Для образования ионов FeSH+ необходима высокая концентрация ионов S2–, и чем крупнее включения частиц сульфидов, тем выше их способность снижать коррозионную стойкость стали. Поэтому крупный размер обнаруженных в стали частиц MnS играет важную негативную роль. Показано, что дополнительным фактором, способствующим снижению коррозионной стойкости изученной стали, является наличие в поверхностном слое мартенсита деформации, образующегося в процессе механической обработки при изготовлении резанием, шлифовкой деталей из заготовки. Появление этого мартенсита обусловлено низкой концентрацией элементов-аустенитообразователей (0,01 – 0,04 % С, 7,96 – 8,23 % Ni). Cталь на модифицированной диаграмме Шеффлера-Делонга находится в области, где возможно образование мартенсита; расчетное значение Мd(30/50) для нее составило 28 °С. По литературным данным, мартенсит деформации в сталях типа 18-10 вызывает снижение их стойкости к питтинговой коррозии в растворах кислот и солей. Показано, что наличие электрического потенциала активизирует коррозионное воздействие на образцы из стали 18Cr-10Ni в кислотной среде. Сделан вывод, что коррозионному повреждению деталей из исследованной стали способствовало наличие скоплений частиц сульфидов в отдельных участках металла в сочетании с присутствием в этих участках мартенсита деформации.
A. S. Vusikhis, L. I. Leont’Ev, E. N. Selivanov, S. V. Sergeeva, S. N. Tyushnyakov
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-205-210

Abstract:
Значимость исследований по восстановлению металлов из оксидных расплавов связана, в первую очередь, с пирометаллургической переработкой руд черных и цветных металлов. Так основной задачей в ходе переработки окисленных никелевых руд является повышение извлечения ценных металлов при требуемом (10 – 20 %) содержании никеля в ферроникеле и минимальном количестве примесей. С помощью методов термодинамического моделирования дана оценка показателям, достигаемым при восстановлении железа и никеля из оксидного расплава. Проведено две серии расчетов. В первой серии состав рабочего тела меняли по количеству оксидов железа и никеля при соотношении СFeО /СNiО, равном 10. Во второй серии при содержании СNiО , равном 1,8 %, варьировали СFeО для соотношений СFeО / СNiО от 10 до 20. Дозированное повышение количества СО в рабочем теле позволило проследить изменение составов оксидного (СМеО ) и металлического (СМе ) расплавов, а также степеней перехода никеля (φNi ) и железа (φFe ) в металлическое состояние. Корреляционные зависимости СNiO , φNi = f (C0 , VCO ) представлены в виде полиномов второй степени. Показатели φNi и φFe меняются с количеством введенного восстановителя, но мало зависят от состава исходной конденсированной фазы. На состав формируемого сплава Fe – Ni влияют содержания элементов в исходном расплаве и количество введенного восстановителя. Для сплавов характерно высокое (65 – 90 %) содержание никеля. Значение φNi около 98 % достигнуто при количестве введенного СО около 80 м3 на 1 т расплава. При этом степень восстановления железа не превышает 5 %. При соотношении СFeО / СNiО , равном 10, содержание никеля в сплаве практически не зависит от содержания его оксида в исходном рудном расплаве и близко к 65 %. Увеличение СFeО / СNiО с 10 до 20 приводит к изменению СNi соответственно от 68,5 до 52,9 %. Полученные данные значимы для обоснования технологии переработки низкокачественных окисленных никелевых руд с выделением ферроникеля требуемого состава.
V. I. Odinokov, E. A. Dmitriev, A. I. Evstigneev, S. Yu. Aleksandrov
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-237-243

Abstract:
A significant influence on stability of the process of filling the CCM mold with liquid metal is exerted by the structural and technological schemes and designs of used devices, modes and parameters of filling the mold with the melt. All this is due to the features of the devices used and the improvement of their design. The high requirements for such devices have determined the need to create new devices designs to reduce the time spent on preparation for work and maintenance and to improve the quality of resulting metal billets. In scientific literature, including patents, more and more articles and materials are devoted to the development of new and improvement of the existing methods of supplying and stirring liquid metal in CCM and devices for their implementation. Experimental studies of liquid metal flow in CCM are a long, complex and laborious process. Therefore, mathematical modeling by numerical methods is increasingly used for this purpose. The authors have proposed a new technology for pouring liquid metal into a mold and a device for its implementation due to the use of effect of a deep-bottom submersible nozzle rotating in the mold with eccentric outlet holes. The purpose of this work is to simulate by proven numerical method a new process of filling a rectangular CCM mold with liquid steel and stirring it. Based on the developed numerical schemes and algorithms, a calculation program was compiled. The article describes an example of calculating the steel casting into a mold of rectangular cross-section and flow diagrams of liquid metal in it.
, A. A. Smorokov, A. S. Kantaev, D. S. Nikitin, G. Yu. Vit’Kina
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-178-183

Abstract:
Titanium dioxide is the most common titanium-containing product on the world market, and the demand for it is increasing. The global consumption of TiO2 is 7 – 7.5 million tons annually. Titanium dioxide is mainly obtained from ilmenite and rutile concentrates. The largest producers are China, USA, Germany, UK, Mexico, and Saudi Arabia. In addition to the natural resources of titan, there are man-made sources. This type of resource includes titanium-containing slags obtained as a result of pyrometallurgical processing of ores and concentrates containing titanium dioxide. These slags, in addition to titanium dioxide, contain silicon in the form of dioxide, silicates or aluminosilicates, whose chemical processing is difficult due to their high melting point (more than 2000 °C) and the chemical stability of these compounds in mineral acids (sulfuric, nitric, hydrochloric). Processing of such raw materials is carried out by “classical” chlorine and sulfuric acid methods. The use of fluorides in industry is realized in the production of aluminum, zirconium, uranium, beryllium, niobium, etc., which indicates the possibility of using fluoride methods for titanium slags processing. The article discusses a method for producing titanium dioxide based on the use of ammonium hydrodifluoride NH4HF2 , which has a high reactivity to a number of chemically resistant oxides (oxides of silicon, titanium, aluminum, etc.). The fluoroammonium method for processing titanium slag using NH4HF2 involves slag decomposition of in NH4HF2 melt followed by silicon admixture sublimation. Cleaning from iron, aluminum and other impurities is carried out using a solution of NH4HF2. Further precipitation of titanium with treatment of the precipitate by AlCl3 and ZnCl2 solutions followed by calcination allows to obtain a rutile modification of titanium dioxide.
, V. V. Farafonov, V. P. Meshalkin
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-214-216

Abstract:
To select the compositions of high-entropy alloys (HEA) consisting of five or more elements, it is necessary to use methods that take into account many variables and the complexity of assessing the relationships between them. Based on chemical information approaches to the analysis of Web of Science databases, data on the frequency of use of chemical elements in the described HEAs were obtained, which allow us to determine trends in the research and development of new materials.
Y. Zhang
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-230-236

Abstract:
The graphitized steel has attracted considerable attention due to its excellent cutability and good properties at cold forming. Compression deformation at room temperature of graphitized steel (0.43 % C) with a ferrite-graphite microstructure was performed on a universal testing machine. Microstructures of deformed samples were studied using the analysis technique of Electron Back-Scattered Diffraction (EBSD). The evolution of microstructure morphology, texture, distribution of Kernel Average Misorintations (KAM) and the Taylor factor in the zone of large deformations of deformed samples with different degrees of deformation is discussed. The results show that the studied steel has a good ability to compression deformation. During compression deformation, with an increase in deformation degree the deformation morphology of the ferrite grain and graphite inclusions gradually stretch in the direction perpendicular to the compression axis and they are represented as fibrous forms. The orientation of ferrite grains in the matrix is gradually obvious, and the orientation of ferrite grains around graphite inclusions is not obvious, that is, the number of grains oriented to , in the matrix is much greater than around graphite inclusion. In addition, KAM and the Taylor factor in the large deformations region of compression samples show that the deformation degree of ferrite grains around graphite inclusions is less than that of ferrite grains in the matrix. The reason for this is that the soft graphite inclusions can reduce the degree of dislocation pile-up.
S. M. Bel’Skii, I. I. Shopin, A. N. Shkarin
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-171-177

Abstract:
At present, the cross-section profile of the rolled strip is characterized by geometrical parameters such as wedge, convex, difference of thickness, displacement of convex, and edge wedge. Some of these parameters are redundant. Techniques for calculating the values of these parameters are known and generally accepted. However, there are features of the cross-section profile of rolled strips, such as local thickenings/thinnings, the methods of calculating values of which are not common: practically every scientific school of rolling scientists or specialists of rolling production use their own techniques, which often produce different results for the same cross-section profiles. The problem of identifying and calculating the local thickenings/ thinnings parameters of the rolled strips cross-section profile is to define a so-called “zero level”, the excess/understatement of which is a sign of local thickenings/thinnings. The paper continues to analyze the accuracy and adequacy of the calculation of the cross-section profile parameters of rolled strips for local thickenings/thinnings. A new method based on statistical methods is proposed. The target function that the thickness distribution across the width of the rolled strip must correspond to is a symmetrical quadratic parabola. However, the actual distribution is always different from the target one for a number of reasons, such as ring wear of the work rolls. In the first step, in the proposed technique, the Walter-Shuhart procedure (control cards) eliminates as emissions of strip thickness values that are dramatically different from the target distribution. But since without excluding the nonlinear (parabolic) component of the measured cross-section profile this procedure cannot be applied, it applies to the first derivative of the cross- section profile thickness distribution function. To determine the “zero level,” after calculating the upper and lower limits of the allowed values of the first derivative, all thicknesses associated with these emissions were eliminated. The result of the repetitive process is a “zero level” according to which the local thickening/thinning parameters are calculated.
S. G. Savel’Ev, M. N. Kondratenko
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-3-184-191

Abstract:
The sintering intensity is an important factor determining techno-economic efficiency of sinter production which provides the blast-furnace process with the main type of agglomerated iron ore raw materials. The charge sintering rate depends on technological parameters of the sintering process. Therefore, a systematic study of sintering technological parameters, which determine its intensity, is of practical and scientific interest. Indicators of the sintering process intensity are considered that assess it from both the mechanical and heat engineering positions. It is shown that in its purest form the sintering process intensity is characterized by the vertical agglomeration rate and combustion intensity of the sintering charge carbon. Two other indexes − the specific productivity for suitable sinter and intensity of heat output in the combustion zone – are less representative for the comparative estimation of sintering intensity, since their values depend on sintered mass strength and thermal effect of carbon combustion respectively. These factors go beyond the essence of the sintering intensity concept. Since content of fines of 5 – 0 mm at different sinter plants is not equal, representative performance comparison of sintering process is possible only taking into account the total amount of fines generated throughout the agglomerate transport path from sinter machine to blast furnace or the results of testing the agglomerate strength in a drum. A comprehensive systematic classification of techniques has been developed to intensify the sintering process based on the material-component principle using four levels of separation – objects, directions, paths and methods in which each subsequent level concretizes and develops the previous one. Its value is universality, which makes it possible to apply a systematization and separation system for almost all already known and future methods of sintering process intensification.
V. V. Solonenko, E. V. Protopopov, M. V. Temlyantsev, N. F. Yakushevich, S. O. Safonov
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-112-121

Abstract:
The article presents the study of the nature of dust and smoke generation during gas-oxygen blasting of a converter bath. The main reasons causing metal waste have been determined. Influence of the process main parameters on metal loss has been studied during dust removal and evaporation of iron in the reaction zone. The authors have estimated the process of metal pulverization due to CO bubbles floating, determined by the rate of their rise to the bath surface. Specifics of temperature regime of the reaction zone and heat balance have been determined when adding fuel to the oxygen flow. Adding fuel to oxygen makes it possible to increase heat input into the bath, while reducing the rate of decarburization. This enables reduction of dust discharge during rupture and crush of metal films by gas bubbles. The effect of combustion products oxygen use on metal impurities oxidation is considered. By the example of blasting carbon and alloyed steel for mill rolls, it has been shown that the degrees of CO2 and H2O decomposition in the bath are the main qualities of gas-oxygen blasting. These indicators determine the oxidizing and heating properties of the blast. Assessment of change in total, consumed heat and its losses with exhaust gases, depending on degree of the oxygen flow dilution with natural gas (methane), has been carried out. Under these conditions, use of submersible combustion torches with change in their oxidizing ability makes it possible to solve various technological tasks, including provision of an effective way to reduce dust emission in converter process.
A. S. Simachev, T. N. Oskolkova, A. A. Umanskii, A. V. Golovatenko
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-135-142

Abstract:
Metallographic and X-ray studies of continuously cast billets of E90KhAF rail steel have been carried out. We have established the regularities of non-metallic inclusions distribution over the crystallization zones before and after billets deformation. It was revealed that in crustal zone the main non-metallic inclusions are point oxides, aluminum nitrides, iron silicates (FeO·SiO2) and alumosilicates (Al2O3·SiO2). They were identified in the zone of columnar crystals. In central zone of the billet, manganese sulfides (MnS), manganese silicates (MnO·SiO2), alumosilicates (Al2O3·SiO2), iron silicates (FeO·SiO2), and point oxides were found. It has been determined that concentration and size of nonmetallic inclusions tend to increase from the surface to central zone of continuously cast billets, which is consistent with generally accepted ideas about mechanisms of billet formation during crystallization. The mechanism of deformation of two-phase silicate non-metallic inclusions and their influence on quality of rail products was disclosed. It is shown that inhomogeneous deformability of complex silicate inclusions aggravates their harmful effect on rail products quality. In this case, additional stresses appear in addition to inclusion-matrix deformation and contact stresses existing at interphase boundaries. This pattern also holds for non-deformed silicate inclusions. Such a distribution of inclusions in the billets volume somewhat reduces their negative effect on rails quality, since near-contact layers of the billet undergo more intense deformation during rolling, and as the axial zone of a billet is approached, deformation rate decreases.
N. A. Cheremiskina, N. V. Shchukina, N. B. Loshkarev, V. V. Lavrov
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-89-94

Abstract:
One of the most energy-intensive industries is ferrous metallurgy. The metallurgical sector in industrially developed countries is reducing its specific energy consumption per one ton of products by approximately 1.0 – 1.5 % per annum. In Russia, obsolete technology is the main reason for the high-energy intensity of industrial product. Energy saving in industrial production is associated with production technology and the scope of fuel and energy resources consumption. Therefore, ways to improve energy efficiency focus on reducing energy consumption of any kind during a specific process in a specific process or thermal unit. Ensuring the economical operation of furnace units requires detailed preliminary and verification analyses, upgrading and introduction of state-of-the-art equipment. The study presents a flow diagram and features of thermal operation of a new drum-type chamber furnace for heating metal products for quenching. The technical parameters of the furnace, the results of the thermo-technical analysis, the heat balance and the specific fuel consumption as applicable to the created design are also presented. The flow diagram of the furnace has significant advantages in terms of the energy efficiency of fuel as compared to the roller and conveyor methods of metal transportation. Placing blanks on the drum significantly reduces the complexity of their transportation. Thanks to its small length the proposed design is compact and easy to place in a workshop. The use of a recuperative fuel burning device allows the efficient use of the heat of waste gases in the heating process. The proposed design and method of products transportation in the furnace working space can be used for the heat treatment of bars, pipes, strips, as well as rolled steel of various shapes.
E. V. Polevoi, Yu. N. Simonov, N. A. Kozyrev, R. A. Shevchenko, L. P. Bashchenko
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-95-103

Abstract:
A thermokinetic diagram of decomposition of supercooled austenite of R350LHT steel was constructed based on the results of its dilatometric, metallographic and hardness analysis during continuous cooling and in isothermal conditions. It was found that cooling at a rate of 0.1 and 1 °C/s causes the austenite decomposition in R350LHT steel by the pearlite mechanism. After cooling at a lower rate, the pearlite structure is coarser and has lower hardness (289 HV). This is due to the higher temperature range of transformation, in which diffusion processes associated with the transformation of austenite into pearlite occur more actively. In the range of rates from 5 to 10 °C/s, the austenite decomposition occurs according to the pearlite and martensitic mechanism, which leads to the formation of a pearlite-martensite structure. When the austenite of the steel under study is cooled at a rate of 30 and 100 °C/s, the austenite transforms according to the martensitic mechanism, and a martensitic structure with high hardness is formed. With an increase in the cooling rate of R350LHT steel, an increase in hardness is observed from 289 (at 0.1 °C/s) to 864 – 0 896 HV (at 100 and 30 °C/s, respectively). The conducted studies allow the boundaries of the search for optimal parameters of welding and heat treatment modes of the investigated rail steel to be narrowed. To obtain the required structures and physical and mechanical properties (austenite of R350LHT steel undergoes decomposition by the pearlite mechanism), cooling should be carried out at a rate of no more than 1 °С/s.
O. S. Lekhov, A. V. Mikhalev
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-143-148

Abstract:
The problem statement and boundary conditions for calculation of axial thermoelastic stresses in backups with collars of the unit of combined continuous casting and deformation are provided for production of three steel billets. The scheme of calculations for determination of thermoelastic stresses in backups with collars in known temperature field was stated using ANSYS software. The results of calculation of thermoelastic stresses in shaped dies were performed in four sections of a backup with collars. In each section, calculation results are given for four typical lines and seven points. Values of axial thermoelastic stresses for seven typical points of each section are given for the contact surface of a backup with collars and the contact layer at a depth of 5 mm from the contact surface. The stress state of a shaped backup in the middle of depression between the middle collars was determined and the regularities of distribution of axial and equivalent stresses over the thickness, length and width of a backup were established during slab compression and at idle. The results of calculation of thermoelastic stresses in the top of the middle collar of a shaped backup on the contact surface and in the contact layer during slab compression and at idle are presented. Graphs of thermoelastic stresses distribution along the line passing through the top of a collar are given, which show the zones of compressive and tensile thermoelastic stresses during slab compression and at idle. The character of the stress state in the base of extreme collar was determined for production of three steel billets in the unit of combined process of continuous casting and deformation.
A. A. Metelkin, O. Yu. Sheshukov, M. V. Savel’Ev, O. I. Shevchenko,
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-104-111

Abstract:
The article considers the issues of sulfur removal in the ladle-furnace unit. The sulfur distribution coefficient depends on sulfide capacity of the slag, sulfur activity coefficient, oxidizing potential of the medium and equilibrium constant. The sulfide capacity CS of slags is one of the most important characteristics of refining capacity of the slags used in extra-furnace steel processing. One of the factors affecting the sulfide capacity is temperature. The formula was proposed showing the dependence of sulfide capacity on the optical basicity and temperature, in the temperature range of 1650 – 1400 °C and when the optical basicity Λ is not more than 0.75; the error of the presented formula does not exceed 6 %. The formula for calculating the optical basicity is proposed, which takes into account the influence of basic, acidic oxides and amphoteric oxide Al2O3. It is shown that slags, completely consisting of a homogeneous phase, have an increased optical basicity of aluminum oxide. Heterogeneous slags have a reduced optical basicity of Al2O3 in comparison with homogeneous slags. Perhaps, this fact can be explained by the fact that in homogeneous slags there is a deficiency of the basic oxide CaO and in the conditions under consideration Al2O3 compound begins to exhibit more basic properties than acidic ones, thus, in homogeneous slags, the optical basicity of aluminum oxide is increased and approaches optical basicity of CaO oxide. Calculations carried out on the basis of real heats have shown that with an increase in the content of Al2O3 oxide in the slag, its optical basicity decreases. Known value of the optical basicity makes it possible to determine sulfide capacity of the slag, sulfur distribution coefficient between metal and slag, and, accordingly, final sulfur content in the metal. The research results have shown that it is advisable to apply the ionic theory of slags for the sulfide capacity determination.
Yu. L. Krutskii, , T. S. Gudyma, , T. M. Krutskaya
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-149-164

Abstract:
The properties, applications and methods for producing titanium and vanadium diborides are considered. These diborides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Titanium and vanadium diborides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technics. So, they are used as surfacing materials when applying wear-resistant coatings on steel products. It is also possible to use vanadium diboride as a catalyst in organic synthesis and the anode in renewable electrochemical current sources. Perspective are ceramics B4C – TiB2 and B4C – VB2 , which make it possible to obtain products based on boron carbide with high-quality performance characteristics, in particular, with increased crack resistance. Such composite ceramics are obtained by means of hot pressing, spark plasma sintering and pressureless sintering. The properties of refractory compounds depend on the content of impurities and dispersion. Therefore, to solve a specific problem associated with the use of refractory compounds, it is important to choose the method of their preparation correctly, to determine the admissible content of impurities in the starting components. This leads to the presence of different methods for the synthesis of borides. The main methods for their preparation are: synthesis from simple substances (metals and boron); borothermal reduction of oxides; carbothermal reduction (reduction of mixtures of metal oxides and boron with carbon; metallothermal reduction of mixtures of metal oxides and boron; carbide-boron reduction. Plasma-chemical synthesis (deposition from the vapor-gas phase) is also used to obtain diboride nanopowders. Each of these methods is characterized in the article.
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-129-134

Abstract:
The article considers a review of domestic and foreign works on the use of intense pulsed electron beams for surface treatment of metals, alloys, cermet and ceramic materials. The advantages of using electron pulsed beams over laser beams, plasma flows, and ion beams are noted. The promising directions of using electron-beam processing were analyzed and are as following: 1 – smoothing the surface, getting rid of surface microcracks, while simultaneously changing the structural-phase state of the surface layer, to create high-performance technologies for the finishing processing of critical metal products of complex shape made of titanium alloy Ti-6Al-4V and titanium; steels of various classes; hard alloy WC – 10 wt. % Сo; aluminum; 2 – removal of microbursts formed during the manufacture of precision molds (SKD11 steel) and biomedical products (Ti-6Al-4V alloy); 3 – finishing the surface of molds and dies; 4 – improvement of the functional properties of metallic biomaterials: stainless steel, titanium and its alloys, alloys based on titanium nickelide with shape memory effect, and magnesium alloys; 5 – processing of medical devices and implants; 6 – formation of the surface alloys for powerful electrodynamic systems; 7 – improvement of the characteristics of aircraft engine and compressor blades; 8 – formation of thermal barrier coatings applied to the surface of the combustion chambers. It is shown that with the correct choice of process parameters, such as accelerating voltage, energy density of electron beam, number of pulses, and pulse duration, it is possible to control carefully and/or manipulate the characteristics of structural-phase state and surface properties. In order to improve the properties of the material and the durability of the products made of it, an important factor is the structure modification to form a submicro-nanosized grain (or subgrain structure).
M. I. Aleutdinova,
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-2-122-128

Abstract:
The possibility of improving the characteristics of a dry sliding electrical contact with a current density higher than 100 A/cm2 by using a molybdenum counterbody is considered. It is shown that tungsten or metallic materials containing bearing steel (1.5 % Cr) in sliding against molybdenum at a speed of 5 m/s under electric current, forms a contact with low electrical conductivity and high wear intensity. This observation served as the basis of this work. Using optical and electron microscopy of sliding surfaces it was found that strong adhesion in the interface was the main reason for rapid surface layers deterioration and high wear intensity. A well-known statement was taken into account that adhesion is due to the low oxide content between the contact surfaces. Visual study of molybdenum sliding surface made it possible to establish formation of a thin transfer layer and absence of traces of oxide formation. The same was observed on sliding surface of tungsten that was caused by high temperature of tungsten and molybdenum oxides formation. A layer of iron oxides was observed on sliding surface of steel containing materials. In addition, traces of a thin tribolayer were find out. An increase in concentration of steel in the primary structure led to a slight increase in iron oxides on the sliding surface, but did not lead to a significant increase in electrical conductivity and wear resistance of the contact. Unsatisfactory characteristics of the contact allowed us to conclude that it is impossible to significantly improve sliding parameters with current collection against molybdenum and inappropriateness of its use as a counterbody for these conditions.
, K. A. Osintsev, , , I. A. Panchenko
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-68-74

Abstract:
A non-equiatomic high-entropy alloy (HEA) of the Al – Co – Cr – Fe – Ni system was obtained using wire-arc additive manufacturing technology in the atmosphere of pure argon. The initial wire had 3 conductors with different chemical composition: pure aluminum wire (Al ≈ 99.95 %), chromium-nickel wire (Cr ≈ 20 %, Ni ≈ 80 %), and cobalt alloy wire (Co ≈ 17 %, Fe ≈ 54 %, Ni ≈ 29 %). The resulting sample of high-entropy alloy was a parallelepiped consisting of 20 deposited layers in height and 4 layers in thickness. The alloy had the following elemental composition, detected by energy-dispersive X-ray spectroscopy: aluminum (35.67 ± 1.34 at. %), nickel (33.79 ± 0.46 at. %), iron (17.28 ± 1.83 at. %), chromium (8.28 ± 0.15 at. %) and cobalt (4.99 ± 0.09 at. %). Scanning electron microscopy revealed that the source material has a dendritic structure and contains particles of the second phase at grain boundaries. Element distribution maps obtained by mapping methods have shown that grain volumes are enriched in aluminum and nickel, while grain boundaries contain chromium and iron. Cobalt is distributed in the crystal lattice of the resulting HEA quasi-uniformly. It is shown that during tensile tests, the material was destroyed by the mechanism of intra-grain cleavage. The formation of brittle cracks along the boundaries and at the junctions of grain boundaries, i.e., in places containing inclusions of the second phases, is revealed. It was suggested that one of the reasons for the increased fragility of HEA, produced by wire-arc additive manufacturing, is revealed uneven distribution of elements in microstructure of the alloy and also the presence in material volume of discontinuities of various shapes and sizes.
N. S. Surikova, I. V. Vlasov, L. S. Derevyagina, A. I. Gordienko, N. A. Narkevich
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-28-37

Abstract:
В работе методами механических испытаний, оптической металлографии, электронной просвечивающей и растровой сканирующей микроскопии исследовано влияние трех режимов многопроходной поперечно-винтовой прокатки (ПВП) на микроструктуру, механические свойства и вязкость разрушения феррито-перлитной трубной стали 09Г2С. Показано, что после всех режимов ПВП наблюдается изменение параметров исходной зеренной структуры заготовки с формированием слоистости в распределении зерен по размерам – вблизи поверхности заготовки размер глобулярных зерен составляет 1 – 4 мкм, длина вытянутых зерен в центральной части заготовки варьируется от единиц до десятков мкм, ширина – от 1 до 8 мкм. Механические испытания на одноосное растяжение и ударную вязкость проводили на образцах, вырезанных из центральной части прутка. Установлено, что ПВП приводит к увеличению предела текучести и предела прочности стали после всех исследуемых режимов при незначительном понижении общей пластичности. Наибольшее увеличение ударной вязкости при Т = –70 °С наблюдается после контролируемой ПВП в интервале температур 850 – 500 °С. С помощью электронно-микроскопических исследований показано, что особенности механического поведения образцов после ПВП связаны со структурными превращениями, происходящими в стали при прокатке и охлаждении. Основным фактором упрочнения является измельчение ферритных зерен и формирование субзеренной структуры после ПВП. Повышение ударной вязкости связано с более однородной мелкодисперсной структурой проката, не содержащей пластин цементита и бейнита. Процессы разрушения исходных образцов стали и после ПВП в зависимости от температуры анализируются на основе записанных диаграмм ударного нагружения и структур в зонах долома образцов Шарпи.
S. V. Samusev, A. V. Kondrushin, V. A. Fadeev
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-21-27

Abstract:
One of the effective methods for studying any process is its physical modeling, during which it is possible to verify the concepts and hypothesis obtained previously by theoretical modeling. In the laboratory of metal forming of NUST “MISIS” there is ERW mill 30 – 50 for the production and simulation of processes for the continuous forming of longitudinal welded pipes of small and medium diameter, their welding and calibration. This article discusses the deformation zone of a pipe billet, using the first two stands of a molding mill as an example with a calibration of a roll tool for a pipe diam. 50×1.5 mm. Based on the analysis of methods for calculating the parameters of real roll calibers, a model of contact interaction of the pipe billet with the first and second roll open stands was developed and areas of the deformation zone were determined including their sizes: non-intensive and intense impact; input and output contact zones; springing up. Analyzing the conditions of contact interaction of the pipe billet with roll calibers, parameters of the pipe billet in contact with the first-caliber rolls were determined in seven sections, taking into account the features of continuous forming. An analysis of the results has shown that the maximum longitudinal deformation occurred at the edge of the billet in section B – B and was equal to 1.04 %, and for the pipe billet bottom it was 0.92 %. For the experiment, a grid was applied to the pipe billet using a laser engraver. During forming, the trajectory deviation of the pipe billet bottom from horizontal axis was recorded, and sizes of the forming sections were determined. Comparison of theoretical and experimental values has shown that the discrepancy between them does not exceed 7 %.
E. A. Maksimov, R. L. Shatalov, V. G. Shalamov
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-14-20

Abstract:
Показано, что практически все технологические процессы изготовления металлопродукции методами пластической деформации связаны с формированием в готовых изделиях самоуравновешенной системы остаточных напряжений. Уровень остаточных напряжений является во многих случаях важным параметром, определяющим качество изделий, полученных в результате пластического деформирования. Причины образования остаточных напряжений многообразны: неоднородность пластической деформации, температурного поля, фазовые превращения и др. По своей величине они могут превосходить напряжения от внешних нагрузок. В настоящее время к металлопродукции предъявляют дополнительные требования с целью создания машин и конструкций, работающих в условиях высоких нагрузок и скоростей, резких колебаний параметров внешней среды. Опыт эксплуатации конструкций в различных областях техники и результаты многочисленных экспериментов показывают, что остаточные напряжения существенно влияют на надежность и долговечность машин и механизмов. На основе теории о разгрузке А.А. Ильюшина получены аналитические зависимости для расчета эпюры изменения остаточных напряжений по толщине листа при изгибе под роликами правильной машины (РПМ), а также угла пружинения. Рассмотрено образование эпюры остаточных напряжений по толщине листа при правке для второго, третьего и последующих роликов РПМ. Установлено, что в результате принципа суперпозиции эпюра остаточных напряжений под вторым и третьим роликами складывается, образуя суммарную эпюру после второго и третьего роликов. Для четвертого, пятого, шестого и последующих роликов РПМ также происходит алгебраическое сложение эпюр остаточных напряжений. Показано, что для листа из стали 45 толщиной 10 мм, шириной 500 мм, r/h = 200 максимальные растягивающие остаточные напряжения 200 МПа наблюдаются на расстоянии Z/h = 0,3 от нейтральной линии по толщине листа. Сравнительный анализ показал, что для данного листа расхождение между опытными и расчетными значениями остаточных напряжений составляет 10 – 26 %, что позволяет рекомендовать методику расчета остаточных напряжений при правке листа на РПМ для оценки качества выправляемых листов.
V. I. Berdnikov, Yu. A. Gudim
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-75-77

Abstract:
Водород используется в основном при восстановительном отжиге порошка железа, получаемого методом распыления жидкого металла водой. Химические аспекты этого процесса моделировали посредством программного комплекса Терра 6.3. В частности, анализировали термодинамическую систему Fe – O − H в широком диапазоне температур и расходов водорода. Из проведенного анализа следовало, что основными примесными соединениями распыленного порошка будут не гидраты железа, а оксид Fe2O3. Однако он не может существовать в атмосфере водорода и преобразуется в оксид Fe3O4 при низкой температуре. Поэтому основной реакцией по восстановлению железа будет реакция Fe3O4 + 4Н2 = 3Fe + 4H2O, завершающаяся при 910 °С. Показано, что эту температуру можно значительно снизить при столь же значительном повышении расхода водорода. Учет этого фактора может быть полезен при отработке режима отжига порошка.
M. Yu. Belomyttsev
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-52-58

Abstract:
Повышенный интерес к многокомпонентному легированию никеля связан с поиском новых составов жаропрочных и жаростойких сплавов на основе никелевого твердого раствора либо его интерметаллидов. В представленной работе изучено сопротивление высокотемпературному окислению сплава системы Ni – Al – Mo – W – Nb, который может быть использован как основа для создания дисперсно-упрочненных инертными частицами карбидов и нитридов двухфазных термически стабильных жаропрочных никелевых сплавов с матрицей из γ′-фазы. Образцы сплава подвергали окислению на воздухе при 900 – 1300 °С в течение 1 – 125 ч. Измеряли уменьшение массы (ΔМ, гр), которое после этого пересчитывали в показатели изменения массы образцов за единицу времени, нормированное на площадь поверхности исходных образцов (Δm, гр/м2 ·ч) и скорость «сгорания» поверхностного слоя (угара h, мкм/ч). Показано, что при окислении сплава Ni – Al – Mo – W – Nb при всех температурах происходит уменьшение массы образцов из-за образования непрочной и рыхлой поверхностной окалины. Зависимости этого показателя от времени окисления близки к линейной. С ростом температуры процессы уменьшения массы интенсифицируются. Предложено повышать окалиностойкость сплава Ni – Al – Mo – W – Nb кратковременным предварительным окислением при 1300 °С в течение 1 ч в атмосфере воздуха. Наблюдаемый эффект повышения стойкости к окислению связан с образованием в окалине слоя из соединения NiAl2O4, более эффективно предохраняющего сплав от взаимодействия с кислородом. Опыты по окислению с использованием инертных меток из платины показали, что механизмом, контролирующим окисление сплава Ni – Al – Mo – W – Nb при высоких температурах в случае наличия на поверхности слоя NiAl2O4 , следует считать диффузию кислорода через окисную пленку вглубь металла. Рассчитана энергия активации процессов окисления образцов сплава Ni – Al – Mo – W – Nb при температурах 900 – 1300 °С и без предварительного окисления. Это значение равно 234 943 ± 13 254 Дж/моль, что характерно для энергии активации процесса самодиффузии никеля.
A. S. Vusikhis, E. N. Selivanov, S. V. Sergeeva, L. I. Leont’Ev
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-46-51

Abstract:
Ферроникель, получаемый в настоящее время из окисленных никелевых руд в различных агрегатах, содержит 5 – 20 % Ni. Экспериментально показана возможность получения богатого (около 70 % Ni) ферроникеля из расплава силикатной никелевой руды в ходе ее обработки газом-восстановителем. Используя методику термодинамического моделирования металлургических процессов, адаптированную к открытым системам, рассмотрены особенности восстановления высокожелезистой разновидности никелевой руды Серовского месторождения монооксидом углерода. Для расчетов принят следующий состав оксидного расплава, % (по массе): 60,4 Fe2O3; 1,4 NiO; 0,14 СоО; 5,8 Аl2O3 ; 17,0 SiO2; 4,2 MgO; 11,1 CaO. Моделирование вели при давлении 0,1 МПа, количестве монооксида углерода в единичной порции 10,6 дм3/кг и температурах 1673, 1723, 1773 К. В ходе расчетов выявлены зависимости, связывающие содержания оксидов никеля (CNiO), железа (СFe2O3 , CFe3O4 , CFeO) и кобальта (CСоО) в оксидном расплаве и металлов в сплаве (СNi, СFe, СCo), а также степени их перехода в металлическое состояние (φNi , φFe, φCo) с количеством введенного газа. Определены содержания металлов в единичной порции восстановленного металла. В интервале температур 1673 – 1773 К и количестве введенного СО, равном 190 дм3/кг, содержание Fe2O в оксидном расплаве составляет 0,17 – 0,12 % , Fe3O4 – 1,77 – 1,05 %, FeO – 55,6 – 56,5 %, NiO – 0,026 – 0,037 %, СоО3 – 0,061 – 0,068 %. При степени восстановления никеля 98 % степень восстановления железа составляет 5 %, а кобальта – 56 – 61 %. В сплаве, сформированном из восстановленных металлов, содержится около 30 % никеля, 63 – 65 % железа и 2 % кобальта. Таким образом, показана возможность при определенных условиях селективного восстановления никеля и кобальта. Полученные данные значимы для обоснования параметров технологических процессов производства ферроникеля из высокожелезистых окисленных никелевых руд.
V. D. Katolikov, I. A. Logachev, O. A. Komolova, M. V. Zheleznyi, A. E. Semin
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-59-67

Abstract:
The development of modern technics is limited by the physical and mechanical characteristics of the produced alloys, properties of which are often determined and enhanced by introduced alloying components. One of the alloying elements that have been very actively introduced in recent years is nitrogen. As a rule, alloying with nitrogen is carried out by ferroalloys, less often by gaseous nitrogen, which has significant advantages. In the processes of special electrometallurgy, alloying with nitrogen can be performed using, for example, nitrogen-containing plasma. Such a method may be feasible in the production of powder metal by spraying the ingot with nitrogen-containing plasma. It is known that performance properties of the products made of powder metal are significantly higher than those of cast metal. This served as a stimulus for investigating the properties of a product obtained from nitrided powder alloy EP741NP. In this work, a study of changes in the chemical composition, microstructure and microhardness of EP741NP alloy samples was carried out. The studied material was nitrided metal powders made on a plasma centrifugal spraying (PREP) unit and ingots from granules obtained by hot isostatic pressing (HIP). The chemical composition of the obtained samples was determined by wave dispersion X-ray fluorescence spectrometry. In order to study the microstructure of metal powders and ingots, the methods of scanning electron microscopy with EDXS were used. Microhardness of the samples was assessed using a microhardness tester by the Vickers method. The analysis of gas impurities was carried out on a gas analyzer. It is shown that nitriding of heat-resistant nickel alloy EP741NP is possible at the stage of metal powder production, without significant loss of alloying components and a sharp change in chemical composition. An increase in microhardness of the obtained nitrided samples was noted in comparison with the initial one.
A. A. Akberdin, A. S. Kim, R. B. Sultangaziev
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-38-45

Abstract:
С использованием метода планирования эксперимента на симплексе изучено поверхностное натяжение расплавов системы СаО – SiO2 – Al2O3 – В2O3. Исследован локальный участок указанной системы, охватывающий процессы производства ферросилиция, силикохрома, цементного клинкера, керамики, стекла, ситталов и др. Содержание оксидов в нем составляло, % (по массе): 9,8 – 52,0 CaO; 0 – 70,4 SiO2 ; 0 – 51,5 Al2O3 и 0 – 20,0 B2O3. Создана математическая модель зависимости поверхностного натяжения от состава расплавов и построены диаграммы в виде сечений тетраэдра по В2O3. Найдено, что в базовой для металлургии системе СаО – SiO2 – Al2O3 расплавы с высоким значением поверхностного натяжения примыкают к бинарной стороне СаО – Al2O3 в районе кристаллизации алюминатов кальция, имеющих малые размеры, высокий заряд и сильную по этой причине связь с объемом расплава. С вводом SiO2 поверхностное натяжение расплавов падает из-за образования крупных алюмокремниевых образований типа [Al2Si2O8]2– , группировок Si2O76- ранкинита, кольцевого комплексного аниона [Si3O9]6– псевдоволластонита. Усложнение анионов за счет полимеризации ведет к падению поверхностного натяжения из-за уменьшения отношения заряда последних к радиусу и, следовательно, силы связи с катионами. Ввод борного ангидрида вызывает снижение поверхностного натяжения расплавов СаО – SiO2 – Al2O3 , что можно объяснить переходом бора при высоких температурах из четырех (BO45-) в трех (BO33-) координированное по кислороду состояние. Образовавшиеся плоские треугольники BO33- или комплексы с их участием слабо связаны с объемом расплава, вытесняются на поверхность и снижают поверхностное натяжение. В наибольшей мере это сказывается на основных алюминатных расплавах, чем на кислых. Последнее объяснено близостью капиллярной активности бор- и кремнекислородных анионов. Экспериментально с применением метода лежащей капли изучены поверхностные явления между продуктами доменной плавки титаномагнетитовых железных руд. Отмечено, что самые высокие силы сцепления (работа адгезии) имеют место между шлаком и греналью (чугун с повышенным содержанием титана и кремния), что и является причиной потерь металла на выпуске со шлаками при переработке таких руд. Загруженный в доменную печь бор (в виде природных руд) в восстановительных условиях перераспределяется между чугуном, греналью и шлаком. Опытами установлено, что присутствие бора в последних на уровне микроконцентраций снижает работу адгезии с 688 до 436 МН/м (на 37 %). Промышленными опытами показано, что это способствовало снижению потерь ценного ванадийсодержащего чугуна со шлаками в 1,2 – 1,5 раза при одновременном улучшении показателей плавки.
S. M. Bel’Skii, I. I. Shopin, A. N. Shkarin
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-7-13

Abstract:
Increasing the level of automation of metallurgical units and the development of industrial information systems increases the number of p ters of production and technological processes available for analysis. The consequence is an increase in the complexity and duration of preliminary data preparation for subsequent mathematical and statistical analysis. It is therefore important to develop new and improve existing techniques for the automated process of primary data production. When developing methods of primary data preparation, it should be taken into account that accuracy and adequacy of results of subsequent mathematical analysis are determined by accuracy and adequacy of used initial data. The cross-sectional profile parameters of hot-rolled strips, such as wedge, convexity, thickness variation, displacement, wedge in near-rim zones, local thickenings and thinning of the strip are calculated parameters, i.e. secondary to actual strip thickness measurements over the length and width of hot-rolled strips. As technology is improved in cold rolling shops, the number of grade groups is increasing, for which technological modes of units and processing routes are selected. They are based on actual values of parameters of cross-section profile in order to further reduce the probability of formation of inappropriate products and increased metal consumption. The presented article provides an overview of conventional calculation methods for parameters of cross-section profile of hot-rolled strip and gives an assessment of accuracy and adequacy of application of the parameters averaged along strip length to the whole strip.
M. V. Kostina, L. Ts. Zhekova
Izvestiya. Ferrous Metallurgy, Volume 64; doi:10.17073/0368-0797-2021-1-78-83

Abstract:
Статья содержит биографию выдающегося ученого-металлурга и металловеда XX века Цоло Рашева. Его жизнь была посвящена развитию металлургии Болгарии, исследованию и разработке металлургических процессов, связанных с получением азотосодержащих и высокоазотистых сталей различных структурных классов и исследованию самих этих сталей. Поскольку его жизнь была неотделима от этой работы, в статье уделено внимание основным направлениям его научной деятельности. Цоло Рашев проводил работы по термодинамике и кинетике взаимодействия нетрадиционных легирующих элементов с металлами и шлаками в жидком и твердом состоянии (в том числе изучение растворимости азота в расплавах различных систем легирования на основе железа); по математическому моделированию металлургических процессов; по технологии и свойствам качественных, специальных и высокоазотистых сталей и сплавов. Разрабатывал и реализовывал на практике методы и устройства для обработки и получения сталей и сплавов, особое внимание уделяя при этом способам и конструкциям для введения и удержания азота в сталях и сплавах на основе железа. Своими работами Цоло Рашев внес неоценимый вклад в мировой фонд научных знаний.
I. N. Tanutrov, M. N. Sviridova, Yu. A. Chesnokov, L. A. Marshuk
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-891-898

Abstract:
From the analysis of data on beneficial use of red mud and oily mill scale, a new direction of recycling has been formulated: the joint processing of these wastes to produce liquid products. Technological modeling of the stage of joint water treatment of a mixture of red mud and oily mill scale was performed at an enlarged laboratory unit. The yields and compositions of the products were determined. A batch of washed sludge was sent for research on obtaining ironcontaining raw materials for subsequent pyrometallurgical processing. With component ratio of 1:1, solid to liquid ratio of 4, temperature of 95 °C and duration of 2 hours, 6.3 kg of the mixture were processed, 6.58 kg of washed precipitate with a moisture content of 21.3 % and 12.6 dm3 of the final solution were obtained. The specific volume of water evaporation was determined to be 31.3 dm3/h per 1 m2 of pulp surface. Compositions of the precipitate iron (54.4 %) and the final solution (1.1 – 1.3 mg/dm3) were established, which indicates an almost complete accumulation of iron in the precipitate. Concentrations in the products of processing impurities were determined: silicon, aluminum, phosphorus, sulfur, sodium oxide and organics. According to the results, a technological scheme for the joint processing of red mud and oily mill scale was developed and ways of using the process products were outlined: sludge – for iron, filtrate – for industrial treatment, evaporated and wash water – for leaching. Using the example of cooperation between enterprises of the Kamensk-Uralsky Industrial Unit, the hardware process diagram is considered. It is advisable to use the data obtained to implement the technology, in particular, to develop technological regulations for the design of a pilot installation.
V. D. Sarychev, S. G. Molotkov, V. E. Kormyshev, S. A. Nevskii, E. V. Polevoi
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-907-914

Abstract:
Mathematical modeling of differentiated thermal processing of railway rails with air has been carried out. At the first stage, onedimensional heat conduction problem with boundary conditions of the third kind was solved analytically and numerically. The obtained temperature distributions at the surface of the rail head and at a depth of 20 mm from the rolling surface were compared with experimental data. As a result, value of the coefficients of heat transfer and thermal conductivity of rail steel was determined. At the second stage, mathematical model of temperature distribution in a rail template was created in conditions of forced cooling and subsequent cooling under natural convection. The proposed mathematical model is based on the Navier-Stokes and convective thermal conductivity equations for the quenching medium and thermal conductivity equation for rail steel. On the rail – air boundary, condition of heat flow continuity was set. In conditions of spontaneous cooling, change in temperature field was simulated by heat conduction equation with conditions of the third kind. Analytical solution of one-dimensional heat conduction equation has shown that calculated temperature values differ from the experimental data by 10 %. When cooling duration is more than 30 s, change of pace of temperature versus time curves occurs, which is associated with change in cooling mechanisms. Results of numerical analysis confirm this assumption. Analysis of the two-dimensional model of rail cooling by the finite element method has shown that at the initial stage of cooling, surface temperature of the rail head decreases sharply both along the central axis and along the fillet. When cooling duration is over 100 s, temperature stabilizes to 307 K. In the central zones of the rail head, cooling process is slower than in the surface ones. After forced cooling is stopped, heating of the surface layers is observed, due to change in heat flow direction from the central zones to the surface of the rail head, and then cooling occurs at speeds significantly lower than at the first stage. The obtained results can be used to correct differential hardening modes.
Yu. S. Kuznetsov, O. I. Kachurina
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-935-945

Abstract:
Thermodynamic analysis of chromium reduction from its oxide in gas phase Н2 – Н2О – СО – СО2 in contact with carbon was performed. Oxidation potential (pO2 ) was determined by two nomograms in the coordinates and taking into account condition normalizations xH2O + xH2 + xCO2+ xCO = 1. In calculations, possible parameters of reduction of chromium from Cr2O3 oxide were determined by ratio of dissociation elasticity of the oxide and oxidation potential of the gas phase. In the СО – СО2 – С system, chromium is reduced at temperature of 1505 K if xCO > 0.9995. At this temperature, Cr2O3 compound is reduced in water gas of the following composition xH2 = 0.0186, xH2O = 0.28·10–4, xCO = 0.9809, xCO2 = 4.86·10–4, for which the oxidation potential is equal to dissociation elasticity of oxide With an increase in hydrogen concentration from 0.0186 to 0.99, oxidation potential of water gas in contact with carbon decreases by four orders of magnitude to This should lead to a significant increase in reduction rate. In such a gaseous atmosphere, it is possible to reduce chromium at temperature of 1230 K. It is technologically simple to obtain reducing water gas and at the lowest cost, for example, by heating water vapor in contact with carbon. It is shown that at temperature of 1500 K water gas is obtained with traces of Н2О and СО2 compounds with parameters xH2 = 0.4999, xCO = 0.4996, Oxidizing potential of such a gas is less than that of chromium oxide, and this difference significantly increases with increasing temperature.
O. S. Lekhov, A. V. Mikhalev
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-960-964

Abstract:
The article describes the main loads affecting shaped backups of the unit of combined process of continuous casting and deformation in billets production. Importance of determining the temperature fields and thermoelastic stresses in shaped backups with collars is provided at formation of several billets, at slab compression and at idle during water cooling of backups. The authors describe strength and thermophysical properties of steel from which the backups are made. Geometry of backups with collars used for obtaining billets of three different shapes in one pass is shown. Initial data of the temperature field calculation are given for backups with collars of the combined unit. Temperature boundary conditions are considered for calculation of temperature fields of backups with collars. Boundary conditions determining temperature of such backups are described and values of the heat flow and effective heat transfer coefficient are given. The results of calculation of temperature fields are performed in four sections and are given for typical lines and points located on contact surface of backups with collars and in contact layer at depth of 5 mm from the working surface. The sizes of finite elements grid which is used at calculation of temperature field of backups with collars are provided. Temperature field of backups with collars is determined on the basis of solution of unsteady thermal conductivity equation corresponding initial and boundary conditions. Values and regularities of temperature distribution in bases and in tops of the middle and extreme edges of the shaped backups are presented during slab compression and at idle when obtaining billets of three shapes in one pass at the unit of combined continuous casting and deformation.
L. I. Leont’Ev, V. V. Tsukanov, D. L. Smirnova
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-873-877

Abstract:
The second part of the article is devoted to the practical realizing of D.K. Chernov’s scientific “predictions”. They were confirmed by him in the implementation of the concepts of points “a” and “b”, structure of the ingot and the possibility, taking into account the knowledge of these temperature boundaries, to build basic modes of deformation and subsequent heat treatment of steel ingots. These materials are supported by a modern interpretation of that provisions and additional materials of the authors.
N. V. Red’Kina
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-965-966

Abstract:
The total solubility of alloying elements (chromium, titanium, aluminum) in the iron-nickel matrix (Fe – Ni) of 44NKhTYu alloy, depending on the number of cycles, does not occur during primary thermocycling processing (TCP). This is evidenced by the main replicas of the matrix with (111) reflection plane indexes of the samples X-ray images under the studied modes of thermocyclic processing. The maximum solubility of alloying elements is achieved only at total quenching. Special attention should be paid to the third and fourth cycles in the further study of TCP changing the cooling rate in these cycles due to the cooling medium, since with an increase in the number of cycles in the primary TCP, significant changes do not occur.
S. V. Myasoedov, S. V. Filatov, V. V. Panteleev, V. S. Listopadov, S. A. Zagainov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-878-882

Abstract:
One of the ways to increase the energy efficiency and intensity of blast furnace smelting, especially when using pulverized coal fuel, is to increase the hot strength of coke. In the conditions of OJSC NLMK, an oil additive was introduced into the coal charge to improve the coke quality. At the same time, sulfur content in the coke increases, and, consequently, sulfur content in the cast iron increases as well. In this regard, the task of finding ways to improve the desulfurization of cast iron in blast furnace becomes urgent. The main factors determining the desulfurization of cast iron are slag basicity, content of MgO oxide in it, temperature of the smelting products, and the slag viscosity. The purpose of this work was to compare the efficiency of sulfur removal by increasing the slag basicity and MgO content. On the basis of wellknown equations, an algorithm was developed that allows the problem to be solved. It was established that an increase in MgO content in the slag promotes desulfurization of cast iron to a greater extent than a basicity increase. In addition, an increase in MgO content by 1 % is accompanied by an increase in slag yield by 3.0 – 3.5 kg/t of cast iron. At the same time, an increase in basicity by 0.01 leads to an increase in the slag yield by 4 – 5 kg/t of pig iron. Consequently, reducing the sulfur content in pig iron by increasing the slag basicity requires less heat. In terms of the specific consumption of coke, difference in heat demand is 0.4 – 0.5 kg/t of pig iron. It is shown that with an increase in MgO content in the slag, the slag viscosity at a temperature of 1450 °C increases to a lesser extent than with an increase in basicity.
A. G. Upolovnikova, A. A. Babenko, L. A. Smirnov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-946-951

Abstract:
Thermodynamic modeling results of lanthanum equilibrium content in metal under the slag of CaO – SiO2 – La2О3 – Al2O3 – MgO system corresponding to chemical composition of 16 points of local simplex plan are presented using the HSC 8.03 Chemistry (Outokumpu) software package in combination with the simplex planning lattice method. In the work, slag is represented by CaO – SiO2 – La2O3 – – 15 % Al2O3 – 8 % MgO oxide system in a wide range of chemical composition for temperatures of 1550 and 1650 °C, and metal contains 0.06 % C, 0.25 % Si, 0.05 % Al (in this expression and hereinafter in mass.%). The results of mathematical modeling are shown graphically in the form of composition - equilibrium content diagrams of lanthanum. There is significant effect of slag basicity on the lanthanum equilibrium content in metal. An increase in slag basicity from 2 to 5 at temperature of 1550 °C leads to an increase in the lanthanum equilibrium content from 0.2 ppm in the region of lanthanum oxide concentration of 1 – 5 % to 7 ppm in the region of increased concentration of lanthanum oxide to 4 – 7 %, hence the increase in slag basicity favorably affects development of lanthanum reduction. Increase in metal temperature also has positive effect on lanthanum reduction process. As temperature rises to 1650 °C, the lanthanum equilibrium content in metal increases from 0.2 ppm in the region of lanthanum oxide concentration of 1 – 3 % to 12 ppm in the region of increased concentration of lanthanum oxide to 4 – 7 %. In diagrams of chemical composition of slag containing 56 – 61 % CaO, 12 – 14 % SiO2 and 4 – 7 % La2O3 , the lanthanum content in metal at level of 7 – 12 ppm is ensured in temperature range from 1550 to 1650 °C. Therefore, there can be confirmed a decisive role of slag basicity, concentration of lanthanum oxide and temperature factor in development of lanthanum reduction from slags of the studied oxide system by aluminum dissolved in metal.
N. A. Popova, E. L. Nikonenko, E. E. Tabieva, G. K. Uazyrkhanova, V. E. Gromov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-915-921

Abstract:
The study was carried out by means of transmission electron microscopy on thin foils to investigate the changes in matrix morphology and phase composition occurring in ferritic-pearlitic steel of St2 grade (Russian) under plasma electrolytic surface quenching. In the original state St2 steel is a material which underwent quenching under the temperature of 890 °C (2 – 2.5 h) with cooling into warm water (30 – 60 °C) and further tempering under the temperature of 580 °С (2.5 – 3 h). Surface quenching was conducted in aqueous salt solution during 4 seconds under the temperature of 850 – 900 °C, voltage of 320 V, and current rate of 40 A. In the original state morphological components of the steel matrix were lamellar pearlite and non-fragmented and fragmented ferrite. Surface quenching resulted in the following transformations of morphology and phase composition: 1 – to martensitic transformation (morphological components are lath martensite, lamellar low-temperature and high temperature martensite), 2 – to steel self-tempering (inside all martensite crystals there are thin plate-like precipitations of cementite), 3 – to diffusion transformation γ → α and precipitation of retained austenite (γ-phase) given as thin layers along the boundaries of laths and plates of low-temperature martensite and inside all the crystals of lamellar martensite in the shape of “needles” like in twin type colonies. Surface quenching led to precipitation of special carbides of Мe23С6 phase. It was revealed that carbide precipitation is attributed primarily to decomposition of retained austenite and martensite and also to partial dissipation of cementite and, moreover, it is due to carbon removal from dislocations and the boundaries of α-phase crystals. That means that in all cases carbon from retained austenite, α-solid solution, cementite particles and defects of crystal lattice is used for the formation of special carbides.
A. N. Maznichevskii, Yu. N. Goikhenberg, R. V. Sprikut
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-899-906

Yu. M. Dombrovskii, M. S. Stepanov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-929-934

Abstract:
Intensification of carburizing and boriding of steel parts is achieved by microarc surface alloying. For carburizing, the parts are immersed in coal powder followed by electric current passing. For boriding, a coating with diffusant is used. Acceleration of diffusion is achieved by action of microarc discharges on the steel surface. The aim of this work was to study the effect of diffusion parameters on thickness, structure, and phase composition of coatings. The samples were made of 20 steel. Surface current density was 0.45 – 0.53 A/cm2. Duration of the process was 2 – 8 min. At the beginning of heating, temperature of the samples increases, and then stabilizes at 930 – 1250 °C due to cessation of micro-formation during combustion of coal particles. After carburizing, a eutectoid mixture is formed on the surface, then, the zone with ferrite-perlite structure is located, which transfers into the original structure. The maximum layer thickness (60 – 390 microns) is reached after 6 – 7 min of heating and then does not increase due to a decrease in the carbon potential during combustion of coal particles. Similar relationship is obtained when boriding: the maximum layer thickness (60 – 340 microns) is reached after 6 – 7 min and then does not increase due to depletion of diffusant source in the coating. At current density of 0.45 A/cm2, the layer consists of a base (a dispersed ferrite-carbide mixture) containing fine inclusions of iron borides and boron carbide. At current densities of 0.49 and 0.53 A/cm2, the layer has heterogeneous structure, with areas of high-hard boride eutectic located at the base. At high current density, diffusion of carbon and boron along the grain boundaries forms Fe – C – B triple eutectic. At lower current density, surface temperature is lower than eutectic formation temperature, so heterogeneous coating structure is not formed. The work results make it possible to choose modes of microarc heating to obtain the required parameters of diffusion layer.
A. A. Brodov, A. A. Gribkov, V. A. Uglov, N. Kh. Mukhatdinov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-867-872

Abstract:
The article describes state of the Russian market of medical instruments and equipment, the volume of production, import and export of medical instruments based on metals, and assesses the import dependence on various market segments. The comparative analysis of domestic alloys and materials produced by foreign companies has shown that Russia has developed unique alloys and steels that have no analogues abroad, with improved indicators of corrosion resistance, wear resistance, static and cyclic strength. However, metallurgical products supplied to the medical industry do not always meet the quality requirements, and medical industry enterprises use imported types of metallic products. It should be noted that for medical purposes, lowtonnage production batches are required, which are associated with increased costs. The situation is aggravated by the fact that some of the enterprises that produced low-tonnage batches of special steels and alloys were completely liquidated. In this regard, it is necessary to create a specialized manufacture of such materials. Results of the analysis of the Russian market of special metals and alloys used for medical needs are presented, and ways to solve the problem of import substitution in this market are suggested.
T. N. Oskolkova, A. S. Simachev, S. I. Yares’Ko
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-922-928

Abstract:
Electro-explosive alloying as a method of pulse-plasma treatment consists in accumulation of energy by a battery of pulsed capacitors and its subsequent discharge for 100 μs through a conductor in form of titanium foil with silicon carbide powder, while conductor is under explosive destruction. Method of electro-explosive alloying of tungsten-cobalt hard alloy includes melting of surface and its saturation with explosion products, followed by self-hardening by removing heat deep into the material and environment. On the surface of VK10KS hard alloy, the coating was obtained with thickness of up to 15 – 20 microns with nanohardness of 26,000 MPa. Using X-ray phase analysis and scanning electron microscopy, it has been established that new phases of TiC, W2C, (W, Ti)C1 – x , WSi2 with high hardness were formed in the surface layer. As a result, friction coefficient decreased to 0.18 compared to the initial 0.41. Investigations with transmission electron microscopy have revealed changes during electro-explosive alloying that occur in surface carbide and near-surface cobalt phases. Dislocations accumulations were found in the carbide phase. In cobalt binder, deformation bands (slip bands), single dislocations, and finely dispersed precipitates of tungsten carbides were revealed. This change can be explained by stabilization of cubic modification of cobalt, crystal lattice of which has a large number of slip planes upon deformation and greater ability to harden in comparison with hexagonal modification of cobalt. Additional alloying with cobalt binder in heat affected zone after pulse-plasma treatment have a positive effect on the service life of tungsten-cobalt hard alloys as a whole due to their stabilization.
N. Kosdauletov, V. E. Roshchin
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-952-959

Abstract:
The article presents thermodynamic modeling results of reduction roasting of ferromanganese ore with a high phosphorus content in the presence of solid carbon. The modeling was carried out using TERRA software package. Influence of the process temperature in the range 950 – 1300 K and carbon content in the amount of 8.50 – 8.85 g per 100 g of ore on reduction of iron, manganese and phosphorus was investigated. With these parameters of the system, iron is reduced by both solid carbon and carbon monoxide CO to the metallic state, and manganese is reduced only to MnO oxide. The degree of phosphorus reduction depends on the amount of reducing agent. With an excess of carbon relative to the reduction of iron, all phosphorus is converted into metal at a temperature of 1150 K. Phosphorus is not reduced at temperatures below 1150 K and such amount of carbon. The process of solid-phase reduction of iron from manganese ore with the preservation of manganese in the oxide phase was researched in laboratory conditions. Experimental results of direct reduction of these elements with carbon and indirect reduction with carbon monoxide CO are presented. The experiments were carried out in the laboratory Tamman furnace at a temperature of 1000 – 1300 °C and holding time of 1 and 3 hours. Results of the research of phase composition of the reduction products, as well as chemical composition of the phases are considered. The possibility of selective solid-phase reduction of iron with solid carbon to the metallic state was confirmed. Iron in the studied conditions is reduced by carbon monoxide CO and passes into magnetic part. During the magnetic separation of the products of ore reduction roasting with solid carbon and carbon monoxide CO, the non-magnetic part contains oxides of manganese, silicon and calcium. The work results can be used in development of theoretical and technological foundations for the processing of ferromanganese ores, which are not processed by existing technologies.
A. B. Yur’Ev, M. V. Temlyantsev, V. B. Deev, A. V. Feoktistov, E. A. Pinaev
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-11-12-883-890

Abstract:
The article presents results of the research of high-temperature gas corrosion of sections of EcoSoderberg electrolyzers’ gas-collecting bells (GSB) made of high-strength VCh50 cast iron with spherical graphite. The gravimetric method was used to study the specific mass losses of the sections due to corrosion. The microstructure of cast iron, structure, chemical and phase composition of corrosion products were studied using optical, electron microscopy and electron microprobe analysis. It was established that the specific weight loss of the sections during operation reaches 0.36 – 0.46 g/(cm2·month). Corrosion of cast iron sections of EcoSoderberg electrolyzers’ GSB is characterized by high unevenness by area. There are cases of decommissioning sections due to local through “burnouts” with a weight loss of 19 – 24 kg. With relatively uniform corrosion, the maximum allowable weight loss of the sections is 25 – 30 kg. To make predictive estimates based on experimental data, dependence of the sections’ mass loss on the operating time was obtained. It was found that the corrosion products of the sections consist of iron oxides and alloying elements of cast iron. Most samples are characterized by increased content of C, S, F, K, Al, and Na. Corrosion products have a pronounced layered structure and contain a large number of defects in the form of pores and cracks. The layers differ in chemical, phase composition, and macrostructure. All the studied samples are characterized by cyclic alternation of relatively dense layers of iron oxides Fe2O3 and Fe3O4 and more porous layers between them. The layers are characterized by increased content of C and F. Sulfur is evenly distributed over the thickness of corrosion products. The studied samples of corrosion products have high defectiveness, friability, large number of pores, cracks, discontinuities, and low adhesion to the surface of cast iron. This is due to the presence of phases and compounds with different coefficients of thermal expansion. The mechanism of corrosion products layers formation was established and scientifically proved.
M. Kh. Ziatdinov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-10-773-781

Abstract:
The article considers research on the history of nitrided ferroalloys appearance and development of technologies for nitrogen-containing steels and ligatures. The most important advantages of nitrogen as an alloying element are its availability and almost unlimited reserves in nature. The technology of nitrogen extraction does not cause any harm to the environment and is not accompanied by the formation of waste. New technologies of nitrided ferroalloys and new compositions of nitrogen-containing ligatures emerged as a response to the creation of new grades of nitrogen-alloyed steels. At the same time, researchers in Europe, the United States, and the Soviet Union made the greatest contribution to the development of nitrided steel and ferroalloys technology. Nitrided ferrochrome emerged from the need for alloying stainless steels of various classes. Nitrided ferrovanadium was created for microalloying high-strength low-alloy steels. For nitrogen alloying of transformer steel, an alloying material based on silicon nitride was developed. Nitrogen-containing compositions based on manganese are universal alloying materials for a wide range of applications. Technologies of nitrided ferroalloys developed in the direction of creating compositions with the maximum nitrogen content with minimal consumption of material resources. Currently, technologies for direct introduction of nitrogen gas into liquid metal during out-of-furnace processing are being successfully developed. Alloying with its solid carriers remains a universal method for smelting nitrogen-containing steels. Nitrogen in nature occurs exclusively in a gaseous form, so for introduction to steel, it is necessary to fix it in the composition of a solid substance. At the same time, such a nitrogen-containing material must be compatible with the steel melt and technological in use. This problem is completely solved by the technology of self-propagating high-temperature synthesis (SHS), which allows obtaining composite ferroalloys based on nitrides, with properties that are unattainable for the furnace process.
S. A. Zaides, . Pham Van Anh
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-10-802-807

Abstract:
Cold drawn calibrated steel is an effective blank for the manufacture of low-rigid cylindrical parts such as shafts and axles. High accuracy of the diametric size along the length of the workpiece, low surface roughness, increased hardness and strength of the surface layer compared to hot rolled products allow us to produce a variety of parts with high metal utilization and high machining performance. The main disadvantage of calibrated metal is the residual stresses that occur during pressure treatment. To reduce or change the nature of the distribution over the cross section, it is proposed to use small plastic deformations in the surface layer of the hire. Known in practice methods of surface plastic deformation (PPD) usually lead to the curvature of non-rigid workpieces. To intensify the stress-strain state in the deformation zone, we propose a method of orbital surface deformation. Based on the finite element modeling, influence of the main parameters of orbital surface deformation on stress state in the deformation zone and residual stresses in the finished products is considered. Compared with the traditional PPD process, the stress intensity during orbital surface deformation will increase by 10 – 15 %. The residual compressive stresses that form in the surface layers reach 70 – 85 % of the material tensile strength. In the second part of the article, it is supposed to provide information on a more effective method of surface deformation and on the change in initial residual stresses that are formed during the calibration of cylindrical rods.
E. O. Pobegalova, V. A. Ivanova
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-10-823-828

Abstract:
The quality metrics of foundry coke are determined by testing at coke plants. Foundry coke consumers are foundry enterprises which are usually located far from the coke plants. Foundry coke is transported in bulk in open railway wagons. Therefore, this paper is aimed to determine the impact of transportation on the quality of foundry coke. The test conditions were as close as possible to real life conditions of foundry coke transportation. To estimate the impact of transportation distance we introduced the destruction index Pт (%). The results of experimental studies have shown that the destruction of foundry coke is not the same at different intervals of transportation. When transporting up to 300 km, the coke with the minimum durability index M40 is destroyed. When the distance is increased from 900 km up to 2500 km, the foundry coke destruction index (Pт , %) increases by 2.08 – 3.02 % depending on the batch. For all batches, a size fraction of less than 40 mm was noted depending on the durability index M40 from 0.25 to 1.41 %. The size fraction of more than 80 mm stays the same for foundry coke with higher durability indices. When the air humidity rises by 40 % during transportation, the amount of moisture in the coke samples of a 40 – 60 mm size fraction is more than 24 times higher than usual, a 60 – 80 mm size fraction – more than 17 times, an 80 mm and larger – more than 10 times. When the air humidity decreases by 34 %, the amount of moisture in a gram of coke of a 40 – 60 mm size fraction becomes 2 times lower than usual, a 60 – 80 mm size fraction – 1.26 times, an 80 mm and larger – 1.45 times. Compared to coke of size fractions 60 – 80 mm and 80 mm and larger, the moisture of the 40 – 60 mm size fraction coke grows faster when the air humidity increases as well.
S. P. Panteikov
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-10-815-822

Abstract:
For the upper blasting lances of 250-tons oxygen converters at PJSC «DMС» (Kamenskoe, Ukraine) the author has proposed a number of welded structures of 5-nozzle lance heads with increased resistance. A set of industrial studies of their operation made it possible to establish that the devices which provide cooling of the areas back from the nozzle zone of the tip have the highest resistance. Measures to increase the values of the average cooler speeds in welded structures of the lance heads and their rigidity also turned out to be quite effective. The transfer of copper welds holding the nozzle inserts in the copper tip from its outer surface to the inner proved to be ineffective from the point of increasing resistance of the lance head (the average resistance of the heads increased by only 7 heats – from 78 to 85 heats). This allows us to assert the need for complete elimination of copper welds in the head (both external, exposed to high-temperature and mechanical stresses, and internal) that hold nozzle inserts in the holes of the welded tip and lance head collector. Thus, in spite of all the measures taken to transfer the welds from the outer surface of the tip to its inner surface, to improve cooling of the tip and its back from the nozzle zones, which also include sections of copper welds around the nozzles, as well as to increase the rigidity of the blast welded structure heads, this led, although to positive, but still to relatively low results. The data obtained indicate that welds made of copper around the nozzle inserts, which are held by this in the tip (also in the collector) of the head, are the limiting link that does not significantly increase the resistance of welded lance heads, and it is urgently necessary to back off its use.
A. V. Fedosov, G. V. Chumachenko
Izvestiya. Ferrous Metallurgy, Volume 63; doi:10.17073/0368-0797-2020-10-856-861

Abstract:
The article considers the issues of monitoring the thermal conditions of alloys melting and casting at foundries. It is noted that the least reliable method is when the measurement and fixing the temperature is assigned to the worker. On the other hand, a fully automatic approach is not always available for small foundries. In this regard, the expediency of using an automated approach is shown, in which the measurement is assigned to the worker, and the values are recorded automatically. This method assumes implementation of an algorithm for automatic classification of temperature measurements based on an end-to-end array of data obtained in the production stream. The solving of this task is divided into three stages. Preparing of raw data for classification process is provided on the first stage. On the second stage, the task of measurement classification is solved by using neural network principles. Analysis of the results of the artificial neural network has shown its high efficiency and degree of their correspondence with the actual situation on the work site. It was also noted that the application of artificial neural networks principles makes the classification process flexible, due to the ability to easily supplement the process with new parameters and neurons. The final stage is analysis of the obtained results. Correctly performed data classification provides an opportunity not only to assess compliance with technological discipline at the site, but also to improve the process of identifying the causes of casting defects. Application of the proposed approach allows us to reduce the influence of human factor in the analysis of thermal conditions of alloys melting and casting with minimal costs for melting monitoring.
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