On the basis of literature and our own data, the effect of boron on characteristics of all stages of metallurgical processes (from sintering, smelting of cast iron and ferroalloys, to steel production) and on the properties of the resulting slag and metal was studied. To intensify the pellets hardening at the stage of liquid-phase sintering and to improve their metallurgical properties, it is sufficient to have 0.20 – 0.35 % of boron oxide in them. According to the laboratory studies, the presence of boron oxide in pellets increases their compressive strength by 1.5 – 1.7 times and hot strength by 3 – 4 times. While studying the mechanism and kinetics of sulfur removal, it was shown that the presence of boric anhydride significantly intensifies processes of pellets desulfurization. Their intensive progress goes to the zones of lower temperatures of 1050 – 1100 °С. To increase the sinter strength characteristics, it is possible to add B₂O₃ to the charge. The introduction of 0.44 % of B₂O₃ does not affect the sinter abrasion. The content of fines (0 – 5 mm) in comparison with the base sample is reduced by 1.5 times. The use of boron pellets in blast-furnace smelting makes it possible to increase the basicity of the final slag from 1.10 to 1.16. In this regard, the sulfur distribution coefficient increases from 48 to 74. The sulfur content in cast iron decreases by 0.005 %. The possibility of using boron and its compounds to improve the technical and economic indicators of production and the quality of pellets, sinter and cast iron is shown on the base of the presented theoretical, laboratory-experimental and industrial data.

The actual problem of increasing the service life of stamped-rolled railway wheels is a complex problem. Residual technological stresses, which cannot be completely eliminated, have a significant effect on the stress-strain state of the wheel as a whole and its disk in particular. At different stages of roughing wheels machining, the residual stress field is continuously changing. This makes it difficult to take into account the residual stresses in the wheels strength calculations. In Report 1 of this work, an accounting method for residual technological stresses was proposed, the essence of which is to set the value of interference between hub and axle when modeling is greater than the actual one. This approach made it possible to obtain additional stresses in the wheel, which adequately reflect the effect of residual technological stresses. In this part of the work, the authors have carried out practical implementation of the developed method and assessment of the degree of residual technological stresses influence on stress-strain state of the wheel disk under the action of operational loads. With regard to the design of a 957 mm diameter wheel with a flat-conical disk (GOST 10791 – 2011), calculations of stress-strain state of the disk under the action of mechanical types of load have been performed. The 60 % increase in the interference between hub and axle realized in the calculations made it possible to establish that the presence of residual technological stresses in the wheel causes an increase of 5 – 38 % in maximum equivalent stresses in the disk zones most loaded during operation. Thus, the proposed method for residual technological stresses accounting allows obtaining an upper estimate of the wheels strength characteristics, and, therefore, more adequately predicting their service life.

The rail steel properties are adversely affected by rigid non-metallic inclusions, containing aluminum oxides. Therefore, aluminum content is limited to 0.004 % wt. in rail steel grades. Aluminum can get into steel from charge materials and refractory lining. In this work, we’ve analyzed how the chemical composition of refractories used in rail steel making influence steel quality on example of one domestic enterprise. To determine the main types of non-metallic inclusions created in E76F rail steels, we have performed fractional gas analysis of the samples taken in various process steps. It was found that the slag composition after degassing changes insignificantly, while the most part of non-metallic inclusions in rail steel is represented by aluminates.

The paper presents the thermodynamic modeling results of zinc and iron reduction from B₂O₃ ‒ CaO ‒ Fe₂O₃ ‒ ZnО melts by CO ‒ CO₂ and H₂ ‒ H₂O mixtures containing 0 – 60 % CO₂ (H₂O) at 1273 – 1673 K using a technique describing the reduction of metals from an oxide melt by gas in bubbling processes, under conditions that provide an approximation to real systems. Its originality is equilibrium determination for each individual portion of gas supplied into the working fluid. The reducible metals oxides content in each calculation cycle is taken from the previous data. During the calculations, changes in the content of zinc (С_ZnO ) and iron (С_Fe2O3 , С_Fe3O4 and С_FeO ) oxides in the melt and the degree of their reduction were estimated. When using CO or H₂ as a reducing agent, this process proceeds in three stages. In the first stage, Fe₂O₃ is reduced to Fe₃O₄ and FeO. C_Fe2O3 values decrease to almost zero, while C_Fe3O4 and C_FeO increase simultaneously. By the end of the stage, С_Fe3O4 reaches its maximum value. At the second stage, the Fe₃O₄ → FeO transition occurs, when С_FeO values reach its maximum. At these stages, there is a slight increase in the C_ZnO . At the third stage, the values C_FeO and C_ZnO decrease, and iron and zinc are reduced. An increase in temperature dramatically reduces the gas consumption for zinc reduction by 2 – 3 times, and the replacement of CO with H₂ reduces it by less than 20 %. In the presence of oxidizing agents (CO or H₂O), only zinc is reduced. The process ends when the final content of zinc oxide in the melt corresponds to the equilibrium with the initial gas composition. The higher the temperature, the less C_ZnO is. The obtained data are useful for the development of technologies for the selective recovery of metals.

One of the applications of construction low-carbon 22K steel (AISI 1022 type) is as a material for the vessel of a core catcher (CC) for nuclear power plants with VVER reactors. In the event of severe beyond design basis accident, the CC-vessel will be under conditions of prolonged hightemperature impacts, which can significantly change the structural state and lead to degradation of mechanical properties of the vessel material. Data on the effect of such actions on the mechanical properties and fracture resistance of welds (the properties of which usually differ from those of the base metal) from low-carbon steels are very limited in the literature. This makes it difficult to guarantee the reliability and safety prediction of CC. The purpose of this work was to carry out the comparative Charpy V-notch impact tests of the samples of base metal and weld metal of the 22K steel welded joint before and after long-term high-temperature heat treatment, simulating the thermal effect on the reactor vessel material of nuclear power plants during severe accidents. Welded joints of 22K steel sheets were obtained by the method of automatic argon-arc welding with a consumable electrode (welding wire SV-08G2S was used) in accordance with PNAE G-7-009–89. Based on the test results, the ductile–brittle transition curves were plotted and analysis of fracture surfaces after tests was carried out. The influence of structural factors on the impact toughness has been studied. It is shown that prolonged high-temperature exposure leads to an increase in the temperatures of beginning and end of the ductile-brittle transition by 30 – 50 °C and to the expansion of range of the ductile-brittle transition temperature by 15 – 25 °C of both base metal and weld metal of the welded joint.

The article considers the temperature distribution in steel during its continuous casting. Temperatures were measured sequentially in the steelpouring ladle (one measurement) and in the tundish (two measurements) using a platinum-platinum-rhodium thermocouple with an accuracy of ±4 °C. We have analyzed the results of 170 casts of two steel grades: 5SP and 35GS. The type of temperatures set distribution was verified on the basis of three goodness-of-fit criteria: Pearson’s χ-square criterion, λ Kolmogorov-Smirnov criterion and W Shapiro-Wilk criterion. The results obtained are consistent with the physical picture of steel casting. The metal in steel-pouring ladle is practically in a stable state and is subject only to natural cooling through the lining, top and ladle body. In the variant of analyzing a sample of temperature values in tundish at the first and second measurements, the hypothesis of normal distribution should be rejected. Here, the steel temperature depends on a number of parameters, including the feed rate and casting rate, feed time and composition of slag-forming and heat-insulating mixtures, etc. Attempts to establish the relationship between the steel temperatures of in steel-pouring ladle and tundish were unsuccessful. Considering the temperature measurement in tundish as two sequential data arrays, the first of which is an argument, and the second is a function, a linear relationship between these arrays was established. This relationship between the first and second temperature measurements in the tundish can be used to estimate the steel final temperature at thermocouple readout, including in the event of a failure. The results of the work can be used in development of a mathematical model of steel casting.

The work is devoted to the problem of flexible small-scale production of galvanized steel of various sizes on a continuous hot-dip galvanizing unit with varying productivity. The main focus is on the heat treatment of steel strip, the requirements for which limit productivity. In conditions of disturbances, it is necessary to proactively control the heat treatment using models, or to reduce the speed of the strip to ensure that the requirements are met. Unlike most of the works that focus on heat control, this work focuses on strip cooling. Based on the analysis of production data of the Magnitogorsk Iron and Steel Works, it is shown that violation of the cooling requirements leads to the appearance of defects in the zinc coating. Dependence of the probability of defects occurrence on the strip temperature is given. Problems of cooling predictive control are formulated using models in the absence of temperature control of the cooling section cavity. For each of the tasks, the model structure and the method of its tuning are determined according to the data accumulated over a significant period of the unit operation under conditions of uncontrolled systematic disturbances. The structure of the cooling control system is proposed by estimation of the cooling section cavity temperature as a controlled variable. The temperature estimate is determined from the model. The lack of measurement of the cooling section cavity temperature is not a problem then varying productivity. The results of the models tuning are presented according to the data of the Magnitogorsk Iron and Steel Works continuous hot-dip galvanizing unit. The proposed structures of the models and methods for their adjustment can be applied in the development of models for metal heating in furnaces.

The article presents mathematical and computer modeling of the behavior of liquid electrode metal drops during the process of electroslag remelting (ESP) at a constant current source. The study of the effect of electric field created by direct current allowed us to show the deviation of the drop trajectory from the electrode axis. The flow of electrons and drops of the electrode metal are exposed to electromagnetic forces, which leads to their displacement relative to the remelted electrode axis. This effect entails destabilization of the liquid metal bath and crystal heterogeneity. In turn, the use of external influence on the flow of ESR process can make it possible to stabilize the liquid metal bath even with the use of direct current. Centrifugal forces can act as such forces. They can arise when implementing the technology with the consumable electrode rotation around its own axis. To establish the optimal parameters of rotation speed, it is necessary to estimate the magnitude of impact of the magnetic field that occurs during direct current remelting process. The modeling was carried out using the Ansys Fluent 16.0 software package on the example of remelting 12Kh18N10T steel under the flux ANF-6. The algorithm for calculating of Ansys Fluent is based on the finite element method. In this paper, the mathematical apparatus was not changed and was used in its initial form. The method of magnetic induction was used. The database of information about the ongoing process was built on a grid of finite elements with certain, but sufficient level of adequacy and quality. Each element contains information about the model at a given point, specified for this modeling process. We have revealed the change in the trajectory of the electrode metal drop by electric field from the opposite direction along which the drop flows. The average length of the path traversed by liquid metal drop from the mold axis to the inner surface is from 5 to 15 cm. The motion of an electrode metal drop without an external magnetic field was simulated. This simulation made it possible to determine (estimate) the direction of movement of electrode metal drops and the indicator of necessary external force to stabilize the liquid metal bath during ESP process at direct current equal to 0.067 N.

Gennadii Nikolaevich Elanskii,
07.04.1937 – 22.06.2021