The conducted studies determined the patterns of influence of chemical composition and deformation parameters of ball steels with experimental chemical composition on their deformability. The development of experimental chemical compositions of ball steels was carried out based on the existing experience of domestic and foreign researchers, taking into account the possibility of further application of the obtained results for ball steels of standard grades. The studies were carried out using a specialized laboratory installation by the method of hot-rolling samples. An increase in the carbon content in the range of 0.72 ‒ 0.85 %, manganese in the range from 0.72 to 0.85 %, chromium in the range of 0.38 – 1.71 % and nickel in the range from 0.08 to 0.87 % has a significant effect on increasing the deformation resistance of steels. At the same time, the quantitative effect of carbon content in the steels on their deformation resistance is much more pronounced in relation to manganese, chromium and nickel. It was determined that a decrease in the deformation temperature from 1200 to 900 °C, an increase in the deformation rate in the range from 1 to 10 s–1 and true deformation in the range 0.05 ‒ 0.35 cause an increase in the deformation resistance of ball steels, regardless of their chemical composition. The influence of all these parameters on the deformation resistance of steels has a pronounced nonlinear character and the deformation temperature has the greatest relative influence on the deformation resistance. The data obtained are summarized in the form of a multiple regression equation, which establishes the quantitative relationship between the resistance of steel to deformation with its chemical composition and deformation para­meters. Verification of the adequacy of the obtained equation in relation to the rolling conditions of ball steel billets of standard grades at the continuous medium-grade mill 450 of JSC EVRAZ United West Siberian Metallurgical Plant confirmed the possibility of using it to predict the energy-power parameters of rolling ball steels of various chemical composition.

The nature of typical flaws of grinding balls from rejected rail steel K76F, which are responsible for unsatisfactory results of tests for impact toughness, are studied. Metallographic analysis of the balls is made with the use of an optical microscope. The degree of contamination of the steel with nonmetallic inclusions is determined by metallographic and x-ray diffraction analyses. The hardness is measured over cross section of the balls. It is shown that the defects lowering the impact toughness of the balls have a steel-melting origin, and the probability of their formation increases with the content of carbon, hydrogen and sulfur in the steel. Increase of the rolling temperature of grinding balls from steel K76F within 900 – 980°C affects positively their impact resistance due to elevation of the ductility of the rail steel and probable welding-up of these flaws under hot deformation.

On the basis of metallographic studies, the authors determined the characteristic defects of grinding balls rolled from the rejects of continuously cast billets of K76F rail steel. Relationship of the presence of internal defects of the balls with their impact resistance was established. Defects in the form of internal cracks with accumulations of non-metallic inclusions in the area of their localization and flocks have the greatest impact on the reduction of balls impact resistance. Such defects are the cause of balls destruction during impact resistance tests in 62 and 17 % of cases, respectively. The effect of internal cracks without significant accumulations of non-metallic inclusions and quenching microcracks located along the boundaries of the phase interface was estimated at 12 and 9 %. The regularities and mechanism of influence of the rejects chemical composition of K76F rail steel billets on the probability of destruction of the balls produced from them during impact resistance tests were established. An increase in sulfur content in the billets of the studied rail steel reduces impact resistance of the balls produced from them, as it contributes to formation of non-plastic sulfides that concentrate in the area of internal cracks. An increase in hydrogen content in rail steel naturally contributes to an increase in probability of formation of the flocks, which significantly reduce the balls stability to shock loads. An increase in carbon content in the initial billets affects the increase in probability of destruction of K76F steel balls during copra tests. It is explained by formation of cementite-type carbides when carbon content corresponding to the eutectoid steel is reached. In general, the relative degree of influence of the K76F rail steel chemical composition on impact resistance of grinding balls is 48 %.

A study of the corrosion resistance of low-alloy cast iron in the environment of anodic gases of aluminum EcoSoderberg electrolyzers was carried out. During the experiments, cast irons not le-gated and alloyed with chromium, aluminum, together with chromium and aluminum were used. The studied samples and compositions of cast iron differ in chemical composition, the structure of the base, the form of carbon in the structure and the form of graphite. The duration of the experiment was 384 days. The corrosion resistance of cast iron was determined by the mass loss of samples and specific mass loss per unit surface per unit time. Of the studied compositions, cast iron containing a minimum amount of aluminum and chromium has the highest corrosion resistance. The mass loss of the samples was 33.8 %, and the specific loss was 1.71 · 10–4 g/(cm2·h). The base of cast iron is ferrite-pearlite, graphite has a flake shape. Cast iron alloyed with aluminum in an amount of 0.64 % and alloyed with aluminum in an amount of 2.74 % and chromium 1.83 % has similar corrosion resistance indicators. The mass losses of the samples were 48.6 and 49.4 %, and the specific losses were 2.57 · 10–4 and 2.51 g/(cm2 · h), respectively. Graphite in such cast irons has a flake-like shape. Cast iron alloyed with aluminum in an amount of 5.51 % has relatively low corrosion resistance indicators, the weight loss of the samples was 64.4 %, and the specific loss was 3.22 · 10–4 g /(cm2 · h). Graphite in the structure of such cast iron has a lamellar structure. Minimum corrosion resistance is typical for cast iron samples with a chromium content of 1.83 %. The mass loss of the samples was 74.0 %, and the specific loss was 3.30 · 10–4 g/(cm2 · h). It is characteristic that cast iron of this composition does not contain graphite secretions, carbon in its composition is in the form of carbides.

The paper considers the effect of combined electromechanical processing in three different modes on the structure and hardness of the surface layers of 40Kh steel, which was in a normalized state (the original structure). The modes differ from each other by the different applied load and the number of pulses. The applied load in modes 1 and 2 (current strength 39 kA, pulse time 0.02 s, number of pulses 1) is 100 and 250 MPa, respectively. A distinctive feature of mode 3 compared to mode 2 is a greater number of pulses (two). Metallographically it was established that in all three cases a hardened surface layer of different thickness (from 300 to 1200 μm) with a hardness of 593 – 598 HV is formed, consisting of two zones (a surface zone with a structure of fine-needle martensite; a transition zone smoothly transitioning into the initial ferrite structure). The transition zone (treatment according to mode 1 ) in its structure contains martensite and ferrite. The transition zone (mode 2 processing) consists of a Widemannstett structure. A more substantial surface heating zone according to this mode (700 μm) in comparison with the processing according to mode 1 (300 μm) in combination with intensive heat removal contributed to the formation of a Widmanstett structure, which is defective and unacceptable for operation. The transition zone with the processing according to mode 3 has the structure of martensite and ferrite. The formation of a defective Widmanstett structure in the transition zone does not occur, since 2 times more pulses are used during processing than in mode 2 . This contributes to the heating of the surface layer to a greater depth (1200 μm), and, consequently, the structure formation in the transition zone occurs from the intercritical interval Ag 3 – Ag 1 .

Studies of the formation of microstructure of grinding balls from the rejects of rail steel were carried out during their quenching in various polymer media. At the first stage, based on studies of the cooling capacity of solutions of polymers PCM and Thermovit with varying concentrations and temperatures, the authors constructed the cooling curves of grinding balls made of K76F rail steel. It was found that at concentration of these polymers in an aqueous solution of 2 and 4 %, cooling rate of grinding balls made of K76F steel is almost identical at solution temperatures of 20 and 30 °C and significantly decreases when the temperature of the polymer solution increases to 40 °C. At the same time, the most noticeable decrease in the cooling rate is characteristic of PCM polymer with its concentration at the level of 2 %. At the second stage, the authors carried out metallographic studies of the microstructure of grinding balls made of K76F rail steel, which were quenched in laboratory conditions using polymers PCM and Thermovit with concentrations of 2 – 4 % and temperature of 20 – 40 °C. As a result, it was determined that the use of the PCM solution for quenching balls provides a significantly higher quality of microstructure and hardness of heat-treated balls compared to the use of the Thermovit polymer. At the same time, varying the concentration and temperature of the PCM polymer quenching medium allows one to obtain grinding balls with different performance characteristics that determine the potential areas of their application. Thus, quenching of balls in a solution of the specified polymer with concentration of 2 % and temperature of 20 – 30 °C ensures the production of balls with high hardness (corresponding to the IV hardness group according to the state standard GOST 7524 – 2015), and the use of a solution of the same polymer with concentration of 4 % and temperature of 20 – 30 °С for quenching creates the possibility of producing balls with lower hardness, but potentially high impact resistance.

The microstructure of cast billets and grinding balls fabricated from rail steels of different chemical compositions is studied. The samples are heat treated by annealing, quenching, and quenching with tempering. The microhardness and the structures of the samples after the treatments are compared. It is shown that chromium alloying above the standardized values causes development of dendritic segregation in the cast structures, which is reduced but not removed completely after the heating for rolling. Assessment of the microstructures and of the hardness of the grinding balls shows that the optimum composition for their production corresponds to rail steel 76KhF.

Исследована микроструктура дифференцированно термоупрочненных железнодорожных рельсов текущего производства АО "ЕВРАЗ ЗСМК". Определены типы неметаллических включений и их состав. Изучены процессы ликвации основных химических элементов рельсовых сталей (С, Si, Mn, Cr, S, P) и изменение твердости по сечению рельсовых профилей. Показано, что характерными неметаллическими включениями являются недеформирующиеся силикаты, наиболее сконцентрированные в шейке рельсов и пластичные сульфиды, сосредоточенные преимущественно в их головке. Для ряда рельсов выявлена химическая неоднородность со скоплениями неметаллических включений в шейке профиля.

Analysis of the existing trends in development of technologies for production of welding and surfacing fluxes showed that one of the actively developing areas is the production of fluxes using man-made waste (including metallurgical one) as components of the initial charge. This is due to the fact that the slag waste of metallurgical production contains a large amount of manganese and silicon, which in turn are the basis in welding fluxes. Within the framework of this direction development, the article describes principal possibility and efficiency of using materials based on ladle electric steelmaking slag from JSC “EVRAZ United West Siberian Metallurgical Combine” and slag produced by silicomanganese from LLC “West Siberian Electrometallurgical Plant” in the charge for production of fluxes used in the surfacing of rolling rolls. All the laboratory tests were made using the equipment of the scientific and production center “Welding Processes and Technologies”. For surfacing steel samples, the authors used a flux additive obtained by mixing ladle electric steelmaking slag of a fraction less than 0.2 mm with liquid sodium glass in a ratio of 62 and 38%. The resulting flux additive was mixed with slag from the production of silicomanganese of a fraction of 0.45–2.50 mm in various ratios. Chemical composition studies (by the spectral method) and metallographic studies of the deposited layer revealed a tendency to an increase in sulfur content and in contamination with non-metallic inclusions in it with an increase in content of the flux additive in the charge of more than 20%. According to the results of visual quality control of the deposited layer macrostructure, the absence of defects was established with a flux additive content of up to 30%.

Исследована микроструктура литых заготовок и мелющих шаров, полученных из рельсовых сталей различного химического состава. Проведена термическая обработка образцов: отжиг; закалка; закалка с отпуском. Осуществлен сравнительный анализ микротвердости и структуры образцов сталей разного состава после термической обработки. Установлено, что легирование хромом сверх нормативных значений и дополнительное легирование никелем рельсовой стали приводит к развитию дендритной ликвации в литой структуре заготовок, которая снижается, но полностью не устраняется после нагрева под прокатку. На основании результатов оценки микроструктуры и твердости мелющих шаров показано, что оптимальной для их производства является сталь, по составу соответствующая рельсовой стали 76ХФ.

The results of surface hardening of tungsten carbide hard alloys carried out using concentrated energy flows are presented. A VK6OM alloy with a thickness of 20 μm is applied on a VK10KS hard alloy by electrospark machining. This results in a surface hardened layer consisting of W2C. The hardness of the resulting layer is 22 000 MPa, the friction factor is 0.23 (compared to the friction factor 0.41 of the original hard alloy), and a strong but low resistant base. In this work, a surface layer was obtained on the VK10KS hard alloy with a thickness of 40 μm, phase composition TiC, W2C, by single-component electroexplosive titanium doping. The nanohardness of this layer is 25 000 MPa, the friction factor is 0.14. A surface layer 3–4 μm thick with the phase composition TiB2, TiC, W2C was obtained on the VK10KS hard alloy by multicomponent electroexplosive titanium-boron doping. The nanohardness of the hardened layer is 27 500 MPa, the friction factor is 0.10. Using a separate cathode technique, an ion-plasma TiN + ZrN coating (50% Ti + 50% Zr) 20 μm thick was deposited on the VK10KS hard alloy surface. Nitrogen was used as the reaction gas. The nanohardness of the surface layer strengthened in this way is 38 500 MPa, the friction factor is 0.07. The ion-plasma TiN + ZrN coating has good adhesion to the substrate. The use of the proposed surface hardening of the VK10KS hard alloy makes it possible to choose one of the hardening methods based on the operating conditions of the hard-alloy tool, to extend its service life, save scarce materials (tungsten and cobalt).

The research investigated the structure and properties of the VK10KS hard alloy after electric spark treatment utilizing the VK6-OM alloy as an electrode in the Turbo and Norma 3 technological modes. We performed scanning electron microscopy and x-ray diffraction analysis to determine the wear resistance, nanohardness, and structure of the VK10KS alloy surface layers after electric spark processing. The study revealed a change in the phase composition of the alloy associated with the formation of ditungsten carbide W2C, which contributed to an increase in the nanohardness of the surface layer with a thickness of 20 – 25 μm to 22,000 MPa. This change also improved the wear resistance of the alloy.

The article analyzes the microstructure of differentially heat strengthened railroad rails produced by the EVRAZ ZSMK Company and determines the types and compositions of nonmetallic inclusions. The segregation processes of the main chemical elements of the rail steels (C, Si, Mn, Cr, S, and P) and the variation of hardness over the cross section of rail profiles were investigated. Typical nonmetallic inclusions are nondeformable silicates concentrated primarily in the rail webs and plastic sulfides concentrated in the rail heads. Some of the rails exhibited chemical heterogeneity with clusters of nonmetallic inclusions in the profile necks.

The effect of rolling parameters for billets and grinding balls during production from the rejects of K76F rail steel exerted on defect formation probability upon deformation has been studied. The simulation of the rolling process for high-grade billets based on the rejects of continuously cast K76F rail steel ingots using a DEFORM-2D software package has provided a significant effect of partial stretching (swaging) coefficients throughout passes, an increased feed turning frequency and rolling temperature exerted on the defect formation probability characterized by a maximum value of the Cockcroft–Latham criterion throughout the feed cross-section. It has been shown that the increase in stretching (swaging) coefficients throughout passes, due to an intensified rolling mode and to an increased turning frequency makes it possible to reduce the probability of defect formation during rolling at the expense of reduced temperature inhomogeneity throughout the feed cross-section. The revealed effect of temperature increase on the reduction of defect formation probability is caused by an increase in the rail steel ductility. Based on the obtained data, general recommendations have been formulated concerning the directions of improving rolling modes for billets made of trail steel rejects, as well as the restrictions of the application of these recommendations in practice. Based on rolling simulation for grinding balls made of rail steel rejects using a helical rolling mill, a significant effect of increased deformation temperature on a decrease in ball crack formation in the axial zone caused by increasing steel ductility has been established. Thus, a novel rolling mode for grinding balls made of the rejects of K76F grade rail steel that provides an increase in impact resistance of grinding balls while maintaining a high level of surface hardness has been developed. The efficiency of this mode has been confirmed by the results of pilot testing with the use of a ball rolling mill at JSC Gur’ev Metallurgical Plant.

Исследована природа характерных дефектов мелющих шаров из отбраковки рельсовой стали К76Ф, являющихся причинами их неудовлетворительных испытаний на ударную стойкость. Проведен металлографический анализ шаров с использованием светового микроскопа. Определена степень загрязненности стали неметаллическими включениями методами металлографического и рентгеновского анализов. Измерена твердость по сечению шаров. Показано, что дефекты мелющих шаров, снижающие их ударную стойкость, имеют преимущественно сталеплавильное происхождение и вероятность их образования увеличивается с повышением содержания углерода, водорода и серы в стали. Установлено положительное влияние повышения температуры прокатки мелющих шаров из стали К76Ф в интервале 900 - 980 °C на их ударную стойкость, связанное с повышением пластичности рассматриваемой рельсовой стали и, как следствие, с увеличением вероятности заваривания дефектов при горячей деформации.

Исследована природа дефектов в железнодорожных рельсах производства АО "ЕВРАЗ ЗСМК" с использованием металлографического и рентгенофазового анализов. Дополнительно проведен регрессионный анализ влияния параметров производства рельсовой стали на вероятность отбраковки рельсов. Рассмотрены механизмы образования внутренних дефектов. Показано, что наиболее характерными внутренними дефектами рельсов, приводящими к их отбраковке при ультразвуковом контроле, являются расслоения со скоплениями непластичных и легкоплавких неметаллических включений. Установлено значимое влияние параметров выплавки и внепечной обработки рельсовой стали на вероятность образования указанных дефектов рельсов.

The article discusses the nature of defects in railroad rails manufactured by the EVRAZ ZSMK company, using the metallographic and x-ray phase analyses. In addition, a regression analysis of the influence of the rail steel production parameters on the probability of rail rejection is performed. The mechanisms behind the formation of internal defects are reviewed. It is demonstrated that the most characteristic internal defects of rails, causing their rejection during the ultrasonic control, are stratifications with the accumulation of non-plastic and low-melting non-metallic inclusions. The parameters of melting and extra-furnace processing of rail steel affect the probability of specified defects formation in rails.

Modification of the surface of VK10KS solid alloy with titanium alongside with boron by the method of pulse-plasma exposure (electro-explosive alloying) is considered. In this case, a superhard (27,500 MPa nanohardness) layer is formed with a thickness of 2.0 – 2.5 μm and a low (μ = 0.10) friction coefficient compared to the friction coefficient of a hard alloy in the sintered state (μ = 0.41). This layer consists of finely dispersed high-hard phases TiB 2 , (Ti, W)C, W 2 C (according to scanning, transmission electron microscopy and X-ray phase analysis). Below is a hardened (with a nanohardness of 17,000 MPa) surface layer (heat affected zone) 10 – 15 μm thick, identified by W 2 C and WC carbides and alloyed with a cobalt binder. This layer smoothly passes into the base. By profilometric studies it was established that after electroexplosive alloying with titanium and boron, the roughness increases ( Ra = 2.00 μm) compared to the initial one ( Ra = 1.32 μm), but remains within the specifications ( Ra = 2.50 μm). The authors have revealed changes that occur in the surface carbide and near-surface cobalt phases during electroexplosive alloying. In the carbide phase, accumulations of dislocations were indicated. In the cobalt binder, deformation bands (slip bands), single dislocations, and also finely dispersed tungsten carbide precipitates were found. This change can be explained by stabilization of the cubic modification of cobalt, the crystal lattice of which has a large number of slip planes during deformation and a greater ability to harden compared to the hexagonal modification of cobalt. Additional alloying with a cobalt binder will positively affect the operational stability of tungsten carbide alloys as a whole due to their stabilization.