The article discusses issues related to the accelerated transition of the Kuznetsk Metallurgical Plant (KMK) to production of armored steel in the conditions of the Great Patriotic War. The prerequisites and conditions for the transition from the production of exclusively peaceful products to the mass production of armored metal were determined. The authors clarified the stages of mastering new production technologies, the contribution of individual departments and production scientists, scientists from the Siberian Metallurgical Institute (SMI) to production of steel for victory. The emergence of Kuznetsk armor is viewed through the prism of contribution of the whole country and people to the common cause of the fight against fascism.

The operational resistance of railway rails is mainly determined by the resistance to contact fatigue defects and wear resistance, and, in addition to the impact characteristics of rolling stock wheels, depends on the chemical composition, structure and mechanical properties of rail steel. Currently, the ways to improve the operational properties of traditional pearlitic rails by increasing the microstructure dispersion are almost exhausted. One of the solutions to increase the service life of rails may be the transition to their production from bainitic steels, characterized by higher mecha­nical properties, resistance to the formation of surface contact and fatigue defects and increased cold resistance. Operational tests conducted abroad in the early 2000s showed that rails made of bainitic steel do indeed have increased resistance to formation of contact fatigue defects compared to rails made of pearlitic steel, but they are subject to more intensive wear. It was concluded that the resistance of bainitic rails to head damage by surface contact and fatigue defects is a consequence of the removal of the damaged rolling surface layer as a result of wear. In 2004 – 2006, JSC EVRAZ United West Siberian Metallurgical Plant conducted research and produced an experimental batch of bainitic rails, which showed the promise of using such steel and the possibility of simultaneously providing increased wear resistance and low-temperature reliability. However, at that time, the plant did not have the full capabilities to ensure the high metallurgical quality of steel: the identified shortcomings are related to the insufficient purity of the metal for non-metallic inclusions. As part of the resumption of work on the development of bainitic rails, two experimental medium-carbon steels B1 and B2, differing in alloying schemes, were smelted, rolled onto rails of type P65 and cooled in calm air. The presented results of mechanical tests showed the positive effect of increased chromium and nickel alloying on mechanical properties and structure.

For many countries the problem of industrial and household waste disposal is particularly acute, since the annual accumulation of all types of waste is quite large (about 7 billion tons), and their reuse does not exceed 30 %. At the same time, industrial waste has a negative impact on living organisms and the environment. Therefore, ways of recycling household and production wastes are necessary. This article considers the problems of utilization, processing (recycling) of industrial and household waste and the prospects of their application in various industries. The influence of different formulations of initial components (microsilica, blast furnace slag, slaked lime), their fractions on physical and mechanical properties of the obtained new composite materials is considered. The obtained materials were investigated in order to determine the values of compressive strength and percentage of water absorption. Thus, all samples have low water absorption percentage (0 – 13.12 %), except for Sample 7 (41.34 %), consisting of 2 parts of microsilica, 1 part of slag and 1 part of lime. It was found that high values of compressive strength are observed in the samples which include microsilica. Samples 3 and 4, composed of microsilica and slag jointly, have the lowest compressive strength of 14.74 and 17.18 kgf/cm², respectively. However, Sample 8, which is composed of 2 parts of microsilica, slag and lime simultaneously, is characterized by the highest compressive strength value of 51.16 kgf/cm². Microsilica has a greater influence on the increase of strength properties. At the same time, the use of industrial waste in the creation of new secondary materials leads to a reduction in the cost of production, expansion of the raw material base of the country, as well as reducing the environmental load of the region.

Using molecular dynamics simulation, the authors studied the influence of misorientation angle and energy of tilt grain boundaries with the misorientation axes \(\left\langle {100} \right\rangle\), \(\left\langle {110} \right\rangle\) and \(\left\langle {111} \right\rangle\) on the melting temperature and nature of early initiation of melting at grain boundaries in austenite. It is shown that with gradual heating, melting begins from the grain boundaries, where there is a violation of the crystal structure and, accordingly, the atoms are located in less deep potential wells. In the case of large‒angle boundaries, melting begins simultaneously along the entire boundary, in the case of small-angle boundaries – in the cores of grain-boundary dislocations. Dependences of the melting temperature of the simulated calculation cells on the angle of grain misorientation and excess energy were obtained. For the misorientation axes \(\left\langle {100} \right\rangle\), \(\left\langle {110} \right\rangle\) and \(\left\langle {111} \right\rangle\), the results were similar. In the region of small misorientation angles (less than 15°), the melting point decreases almost linearly with increasing angle, then, for large-angle boundaries, the decrease becomes less intense. These dependences correlate with the energy of grain boundary formation or with the associated excess energy of the calculation cell. The main quantitative criterion determining the effect of defects on a decrease in melting temperature is excess energy, that is, the energy difference between the considered structure and the ideal crystal, which can also be interpreted as the energy of the consi­dered structure formation. The melting point decreases linearly with increasing excess energy. Obviously, the effect of grain boundaries on the melting point becomes significant only for materials with a very high content of grain boundaries, for example, for materials with a nanocrystalline structure. 

Metallographic studies showed that the use of rare-earth oxide (REO) additives during liquid electrolysis-free boriding increases the borated layers depth, with these additives not interacting with the treated product material. Addition of lanthanum and yttrium oxides increases the borated layer depth by 30 – 40 %, while addition of scandium oxide either has no effect or decreases the layer depth. X-ray phase analysis of boriding alloys with REO additives was conducted in this study. It was shown that REO additions to the melt result in formation of low-melting rare-earth borates (LaBO₃, YBO₃, ScBO₃), which enhance grain boundary diffusion and significantly intensify the boriding process. Estimated values of bulk and grain boundary diffusion coefficients were obtained. The addition of yttrium oxide increased the bulk diffusion coefficient in VKS-5 steel by 280 %. In Kh12MF steel, addition of lanthanum oxide resulted in an 83 % increase in the bulk diffusion coefficient. For 40Kh steel, no increase in the bulk diffusion coefficient was recorded in any of the investigated cases. The grain boundary diffusion coefficient increased in VKS-5 and Kh12MF steels by 1000 % with addition of lanthanum oxide. Addition of yttrium oxide increased the grain boundary diffusion coefficient by 1000 % in VKS-5 steel, by 135 % in Kh12MF steel, and by 87 % in 40Kh steel. Addition of scandium oxide increased the grain boundary diffusion coefficient by 160 % in VKS-5 steel. The diffusion coefficient values at grain boundaries obtained through modeling calculations agree well with the experimental data.

The authors propose a simple theory of thermodynamic properties of liquid nitrogen solutions in alloys of the Fe – Ni and Fe – Cr systems. The theory is analogous to the theory of these systems proposed previously by the authors in 2019 and 2021. It is based on lattice model of the Fe – Ni and Fe – Cr solutions. The model assumes a FCC lattice. At the sites of this lattice are the atoms of iron, nickel and chromium. Nitrogen atoms are located in octahedral interstices. Nitrogen atom interacts only with the metal atoms located in the lattice sites neighboring to it. This interaction is pairwise. It is assumed that the energy of this interaction depends neither on composition nor on temperature and the liquid solutions of Fe – Ni and Fe – Cr systems are perfect. For an infinitely nitrogen-diluted solution of this element in the Fe – j alloy (j = Ni, Cr), a rational nitrogen activity coeffi­cient \(\gamma _{\rm{N}}^0\) is determined. Next, we considered the expansion of the function ln\(\gamma _{\rm{N}}^0\) at a constant temperature in a series in powers of the argument c_j, where c_j is the concentration of the j component, expressed in mole fractions. The coefficient J_n in the term of the n^th degree of this expansion is called the thermodynamic n^th order interaction coefficient of nitrogen with j element in liquid steel. In this case J₁ = \(\varepsilon _{\rm{N}}^j\) is called Wagner interaction coeffi­cient, J₂ = \(\rho _{\rm{N}}^j\) – the second order interaction coefficient. Within the framework of the presented theory the simplest relationship between 
the interaction coefficients \(\varepsilon _{\rm{N}}^j\) and \(\rho _{\rm{N}}^j\) was found. The formula looks like: \(\rho _{\rm{N}}^j = \frac{1}{{12}}{\left( {\varepsilon _{\rm{N}}^j} \right)^2}\). To verify this formula, experimental data on the solubility of nitrogen in liquid alloys of the Fe – Ni and Fe – Cr systems at a temperature of 1873 K, obtained by Satir-Kolorz and Feichtinger (1991) were used. From these data follows: \(\varepsilon _{\rm{N}}^{{\rm{Ni}}}\) = 2.6; \(\varepsilon _{\rm{N}}^{{\rm{Cr}}}\) = –10.2; \(\rho _{\rm{N}}^{{\rm{Ni}}}\) = 0.8; \(\rho _{\rm{N}}^{{\rm{Cr}}}\) = 6.3. The theoretical values calculated using the above formula are as follows: \(\rho _{\rm{N}}^{{\rm{Ni}}}\) = 0.56; \(\rho _{\rm{N}}^{{\rm{Cr}}}\) = 8.67. Bearing in mind the significant uncertainty in the experimental determination of the second order interaction coefficient of nitrogen with alloying elements in iron-based binary alloys, the correspondence between the theoretical and experimental results should be considered satisfactory.

The article presents the results of studying the processes of reduction of iron ore titanomagnetite pellets with synthesis gas by means of thermo­dy­namic modeling using the Terra software package. Its use made it possible to model and predict chemical and phase transformations in iron ore titanomagnetite pellets during reduction using hydrogen-containing synthesis gas, taking into account the effect of temperature, hydrogen concentration and other parameters on reduction. Calculations were performed with different gas mixture contents to evaluate the model efficiency. Content of the CO – N₂ – H₂ – CH₄ gas mixture for calculations varied with an increase in CO and H₂, decrease in N₂ and constant CH₄. Thermodynamic modeling showed that when balance of the main phases in high-temperature systems is achieved during reduction with various gas mixtures, the concentration of distribution of silicon, aluminum, titanium, magnesium, and calcium elements remains constant. Significant changes are observed in the concentration of iron, vanadium, and manganese, which is associated with the features of reduction process and composition of the gases used. Dependences of the system equilibrium composition on temperature at various element contents were obtained. The constructed thermodynamic model describes the reduction process and can be used to optimize it under various production conditions.

The thermodynamic modeling method was used to determine the temperature of beginning of reduction of iron, vanadium, silicon, and titanium in ilmenite concentrate by carbon or hydrogen at different amounts of reducing agent in the system. The amount of excess carbon relative to the stoichiometry of the iron reduction reaction does not affect the temperature of reduction beginning, but determines their reduction degree and the amount of carbides formed. The amount of hydrogen in the system significantly affects the temperature of reduction beginning: with an increase in water amount, this temperature of each element decreases, but to a different extent. The wider temperature range of beginning of reduction by hydrogen and the quantitatively unequal effect of temperature create more opportunities for controlling the solid-phase selective reduction by hydrogen in comparison with carbon. In contrast to the carbothermic process, the solid-phase reduction of titanium by hydrogen is negligible at relatively low temperatures, at which titanium is reduced by carbon and forms carbides. The low solubility of hydrogen in solid iron excludes its influence on the behavior of elements at the stage of separation melting of solid-phase reduction products. This makes it possible to carry out reduction in hydrogen flow by changing the temperature and amount of hydrogen in the reducing gas mixture, and to control the processes of selective solid-phase reduction of elements. The use of hydrogen at the stage of solid-phase reduction makes it possible to selectively reduce iron with the storage of titanium oxides in the oxide phase in form of TiO₂, and after separation of the reduction products by melting, to obtain the products in demand (carbon-free iron and TiO₂ concentrate).

The article presents the results of analysis of steelmaking slags formation. It is shown that currently two methods of steel refining are used in the steelmaking industry – oxidative and reducing. The method of oxidative refining is implemented in electric arc furnaces (EAF), and is primarily aimed at extracting phosphorus from the steel being smelted. Reducing refining is implemented in the ladle-furnace unit (LF) and is aimed at removing sulfur from steel. The features of these processes affect the formation of the phase composition of steelmaking slags. Under conditions of oxidative refining, wustite FeO, magnetite Fe₃O₄, larnite β-2CaO·SiO₂ and merwinite 3CaO·MgO·2SiO₂ are formed in EAF slags, and under conditions of reducing refining in LF slags, mayenite 12CaO·7Al₂O₃, periclase MgO, low–temperature modification of dicalcium silicate – γ-2CaO·SiO₂, CaS and FeO. Of the minerals in the composition of EAF slags and LF slags, mayenite 12CaO·7Al₂O₃ and larnite β-2CaO·SiO₂ have hydraulic activity. Based on the theoretical analysis of the formation of sulfated hydraulically active phases, the possibility of imparting properties of mineral binders to steelmaking slags by grinding without their additional thermal preparation is shown.

Using the example of formalized description of the converter production at JSC EVRAZ United West Siberian Metallurgical Plant consisting of two converter shops with two and three units, it is shown that the issues of planning production volumes and repairs of metallurgical units, building end-to-end schedules of units are complex and multifactorial tasks characterized by the discreteness and non-linearity of the functions describing them. The formalization of the tasks of optimizing production processes with specified constraints and criteria showed that features of the studied process of converter production make it almost impossible to build and use analytical solutions. The approach chosen by the authors to the solution (taking into account these circumstances) is based on the use of a digital discrete event simulation model. Such a model is a digital copy of the investigated process of converter production, reflects its structure, performance, technical condition and parameters: duration of converter campaign, duration of repair periods, etc. The model uses various control mechanisms to solve the problems of distributing the input flow of cast iron between converter shops, forming schedules for the operation of individual converters and their repairs, accumulates information as it functions for the purpose of optimizing and predicting the results of the operation process. It allows one to collect data on the operation of converter production and use predictive analytics tools to plan repairs, provides data that cannot be obtained directly on a physical object and which can be used to optimize system parameters, and generates datasets for visualizing individual results of the operation process.