Development of the metallurgical industry in St. Petersburg played an outstanding role in the history of world and domestic science and technology. The founding fathers of domestic metallurgy: D.K. Chernov and his contemporaries had such a strong influence on the development of metal science that metallurgical science in Russia continued to develop successfully throughout the century and achieved impressive results in the 20^th century and the beginning of the 21^st century both in theoretical and in applied areas. However, the history of metallurgy in St. Petersburg wasn’t systematically covered in scientific and technical periodicals in recent years. Publishing this article in the year of the 300^th anniversary of the Russian Academy of Sciences, we highlight current issues of history, continuity of traditions and prospects for the development of metallurgy in one of the leading regions of our country.

Powder metallurgy of high-entropy alloys has gained significant attention in modern applications due to its low cost and near-net-shape forma­bility. This overview presents the state-of-the-art research on powder metallurgy of high-entropy alloys for high-temperature applications, covering basic solid state fabricating processes, phase composition, and advanced mechanical properties recently attained. The analysis showed that various methods of production and mixing of powder components, including self-propagating high-temperature synthesis, magnesium reduction, hydrogenation, mechanical alloying, plasma spheroidization, centrifugal plasma sputtering of the bar, and conventional mixing of elemental powders in high-energy mixers are used to produce powder mixtures. The most common consolidation method is spark plasma sintering, which allows obtaining compacts with high speed and preservation of fine structure. Also, for the production of long bars and billets, the extrusion of powder mixtures in shells is used. A key feature of the chemical compositions of billets produced by methods of powder metallurgy are the possibility of obtaining oxide-disperse-strengthened powder compacts, which provides additional hardening at elevated temperatures. The main elements used in the creation of high-entropy alloys for application at elevated temperatures are the refractory metals. Therefore, in order to reduce the density of new alloys, compositions with aluminum, titanium, and refractory oxides are being developed. Finally, this review identifies unresolved and critical issues in the development of approaches to obtaining high-entropy alloys using powder metallurgy methods for their practical implementation in modern industry.

The paper presents the findings from the study of the working space of blast furnace No. 5 of PJSC Severstal during its first-category overhaul in 2024 lasting 17.46 years, which significantly exceeded the standard service life. The effectiveness of technological measures taken to extend the furnace’s campaign from 2006 to 2024, aimed at protecting the refractory lining in critical areas such as the hearth, lower shaft, and the upper bosh, was evaluated. The residual thickness of the refractory lining in the shaft, hearth, and metal receiver is analyzed, and maps showing the actual thickness of the lining across different sections are generated. The measured maximum wear of the shaft refractory lining is 344 mm (37.4 % of the original value); the measured maximum wear of carbon blocks in the area of cesspool openings – 313 mm (23.4 % of the original block size). In the upper part of the hearth, the minimum residual thickness of refractories with an Al₂O₃ content of 43 % is 220 mm or 31.9 % of the initial value. The paper also discusses safe remote measurement methods, including 3D laser scanning of the furnace shaft during the removal of residual charge materials. It highlights the advantages of ground-based laser scanners in capturing dense, high-quality 3D geometric data. Additionally, the paper describes the experience of remotely measuring the residual thickness of carbon blocks around the raking openings. Comparisons are made between the actual residual thickness of the refractory lining in the hearth, bottom carbon blocks, and high-alumina refractories of the tuyere zone, and the results obtained using ultrasonic echo-sounding technology (AU-E) during the furnace’s operation. The paper also includes a description of the stress wave propagation technology, which utilizes data analysis in the time and frequency domains to determine lining thickness and detect anomalies. The results of the current and previous blast furnace campaigns are compared in terms of pig iron production, the number of cooling system failures, and refractory wear across the entire working space of the furnace. The total production of pig iron in the 2006 – 2024 campaign, related to the furnace area, amounted to 420.0 thousand tons/m² and exceeded the figure for the previous campaign by 1.90 times.

Blast furnace dust and sludge are by-products of ironmaking that contain high levels of iron and carbon, along with zinc. The increased zinc content complicates their recycling in the sintering and blast furnace processes, leading to their accumulation in waste dumps. This study investigates different treatment methods for recovering valuable elements from blast furnace dust (BFD) and blast furnace sludge (BFS) through reduction roasting and magnetic separation. Thermodynamic calculations and laboratory experiments were conducted to evaluate three approaches: magnetic separation without the roasting, as well as roasting stages to reduce iron to magnetite at 800 °C or metallic iron at 1200 °C, respectively. Direct magnetic separation without roasting and with the preliminary roasting at 800 °C resulted in magnetic concentrates of 49 – 63 % Fe from the BFD and BFS samples, but with elevated zinc content. The best results were achieved using reduction roasting at 1200 °C for 120 min, followed by grinding the samples to –0.054 mm and magnetic separation with a magnetic field of 0.1 T. As a result, the metallized magnetic concentrate containing 73.8 % Fe and 0.048 % Zn was obtained from the BFS sample (initially containing 39.5 % Fe and 0.31 % Zn), while a concentrate containing 80 % Fe and 0.019 % Zn was produced from the BFD sample (initially containing 44.6 % Fe and 0.31 % Zn). The iron recovery into the concentrates for the BFS and BFD samples was 92.8 and 89.7 %, respectively. The proposed approach can produce valuable materials for ferrous and non-ferrous metallurgy from these by-products, increase the efficiency of sintering and blast furnace processes, and reduce waste accumulation.

Hydraulic dumps for storing waste from primary and secondary iron ore processing (tailings dumps) were selected as objects for research. In the course of the study, data on the mineralogical composition of soil-forming rock samples of technogenic landscapes were obtained. This indicator is one of the main factors of soil formation when considering lithology at a lower hierarchical level. The mineralogical composition influences the content and ratio of nutrients and toxicants in soils, ion exchange processes, soil resistance to degradation and overall soil fertility. The mineralo­gical composition is the matrix of soil formation and regulates the transformation, migration and accumulation of matter, energy and information of the external environment and anthropogenic impact in the soil. The hydraulic filling method of waste storage has an impact on the spatial distribution of material in tailings dumps. First of all, a contrasting addition in terms of granulometric composition is distinguished due to the deposition of particles in aqueous conditions under the influence of a gravitational field. The deposition rate depends on the mass, size, shape and density of the particle substance, viscosity and density of the medium, as well as on acceleration, gravity and centrifugal forces acting on the particles. Despite a significant amount of research on the effect of mineralogical composition on soil development, this problem was not sufficiently studied. This determines the absence of generally accepted indicators of the development rate of soils formed on a man-made mineral substrate and the accumulation degree of biophilic elements in such soils.

Corrosion-resistant steels are in demand in the modern world due to their high performance properties and a wide range of applications. Such areas of application include kitchenware, furniture, medical equipment, nuclear reactors, spacecraft, etc. Oxygen in steel, especially in corrosion-resistant steel, is one of the most harmful elements. Oxide inclusions disrupt the homogeneity of the metal, negatively affect the ductility, fracture toughness, fatigue strength and corrosion resistance of steel. In corrosion-resistant steels, non-metallic inclusions (NI) lead to the formation of defects in cold-rolled sheets. Aluminate inclusions also lead to clogging of steel-casting equipment. An analysis of the production technology of corrosion-resistant steel 08Kh8N10T was carried out in order to determine the causes of NI formation that affect the pourability of steel and its quality. The studies determined the content of total oxygen and nitrogen, as well as oxygen bound in various non-metallic inclusions at the stages of ladle processing and continuous steel casting. It was shown that after the introduction of titanium wire into the melt, the total nitrogen content decreases due to the formation and subsequent removal of titanium nitrides. At the same time, the content of titanium oxides in the melt increases. It was shown that the causes of clogging of steel-pouring nozzles during continuous casting are complex non-metallic inclusions based on titanium oxides, which were deposited on the inner surface of the pouring nozzle-doser. Recommendations were made to adjust the technology of steel melting in EAF and ladle processing. Based on the results of electron microscopic analysis, it was established that mixing of refining liquid-mobile slag in ladle steel processing units contributed to the assimilation of non-metallic inclusions by slag and a decrease in their sizes in the metal. After the implementation of the corrective recommendations, clogging of steel-pouring nozzles during continuous casting was not observed.

Indentation is an attractive method for studying the deformation behavior of amorphous alloys for a number of reasons: not being specific to the sample size, these tests are easy to perform and do not lead to macrofracture; plastic deformation in the material is locally limited, which facilitates the study of plastic flow in the zones surrounding and located under the indenter; direct comparison of indentation results with responses, for example, to bending or tension further makes the indentation method an effective “probe” for understanding the physics of plastic deformation and fracture of amorphous alloys. The morphology of microprints of melt-quenched ribbon of Co_70.5Fe_0.5Сr₄Si₇B₁₈ amorphous alloys subjected to heat treatment in a wide range of temperatures was studied after indentation on an elastic substrate. Structural-phase transformations were controlled by X-ray structural analysis and differential scanning calorimetry. We discovered characteristic modifications in the patterns of their deformation and fracture during the transition from amorphous to crystalline state. Three temperature ranges with characteristic deformation zones on the surface of the studied samples were established. At T_room < T_f, amorphous alloy demonstrates unique plasticity. The shear bands appear around the imprint only at the maximum load on the indenter. T_f  ≤ T_an ≤ T_sb is a transitional interval, since cracks do not form at lower temperatures, and there are no shear bands at higher temperatures. The alloy is in an amorphous but brittle state, so radial and ring cracks, as well as spalls, are observed. The interval T_sb < T_an ≤ T_crys corresponds to the final transformation of the alloy into a crystalline state; symmetrical patterns of fracture are formed, consisting of square crack networks. It is possible to give an approximate express assessment of the structural state of amorphous alloys based on an “atlas” of local loading zones (presence/absence of shear bands, cracks, their relative position) compiled taking into account the corresponding temperature intervals under different loads.

In this work, the authors used the methods of modern physical materials science to investigate the structure, defective substructure, phase composition, tribological and mechanical properties of the surfacing subjected to high-temperature tempering at 580 °C and subsequent electron beam processing. The deposited layers up to 10 mm thick are formed by plasma surfacing with PP-18YU powder wire in a nitrogen medium. According to the phase composition, the deposited layers consist of α-Fe and carbides of Me₆C composition. After tempering, the polycrystalline structure of the deposited layer contains grains of 7.0 – 22.5 μm in size with layers of the second phase along the boundaries and at the joints of grains with composition V₄C₃, Cr₇C₃, Fe₃C, Cr₂₃C₆, WC_1 – x. Electron beam processing forms a thin surface layer (30 – 50 μm) with grains of cellular (columnar) structure of high-speed crystallization of submicron (100 – 250 nm) size. Particles of the second phase of the nanoscale range of globular and faceted shapes were detected in the volume of grains and along the boundaries.

Today, researchers and industry are faced with the task of improving the physical and mechanical properties of various metal products. To strengthen the structures, there are various technologies for processing the material surface by high-temperature exposure. At the same time, the use of laser technologies is of great interest. High-speed local laser heating of the material surface followed by rapid cooling with heat removal into the volume depth, as well as the absence of mechanical action, allows us to obtain unique nonequilibrium structures with a wide range of properties. Obviously, the development of these technologies requires deep fundamental research. In this work, the molecular dynamics method revealed the features of structural changes in the surface layers of an iron crystal under high-temperature exposure. The choice of such a method is due to the fact that the phenomena under consideration are difficult to study through real experiments and direct observations. Conditions of the computer experiment were set in such a way that after the melting point is reached, a phase transition occurs in the simulated system, during which particles are separated from the surface of the liquid phase. As a result of the study, the threshold temperature of particle ejection was estimated and the mechanisms of particle cluster formation were investigated. When heated, the number of clusters increases, and when cooled, it decreases, but at the same time their sizes increase, which indicates the implementation of the condensation mechanism of ablation products. Additionally, the influence of external pressure on the simulated particle system was studied. It is shown that as the pressure increases, the number of clusters decreases.

The authors studied the phase composition, crystal lattice parameters, mechanical properties and stress corrosion resistance of high-nitrogen austenitic and austenitic-ferritic Cr – Mn steels after homogenizing treatment, aging and cold plastic deformation. It was established that alloying of Cr – Mn steels with silicon and vanadium can lead to the formation of different amounts of ferromagnetic ẟ-ferrite and, from its low content, to significant hardening due to the grain-boundary effect. The presence of ẟ-ferrite has a hardening effect both after homogenizing treatment and during cold plastic deformation. In vanadium-alloyed Cr – Mn steels, even after austenitization treatment at 1250 °C, a finer grain of austenite of 8 – 9 numbers is retained than those of steels alloyed with silicon, having after quenching from a lower temperature (1150 – 1170 °C) larger grain of 6 – 7 numbers. Formation of even small amounts of ẟ-ferrite leads to a decrease in corrosion cracking resistance of high-nitrogen chromium-manganese steels. At the same time, corrosion resistance of high-nitrogen steels with ẟ-ferrite is significantly lower than that of austenitic steels containing 0.4 % nitrogen and more single-phase Cr – Mn. Aging causes significant hardening of high-nitrogen, alloyed with both silicon and vanadium, Cr – Mn steels with ẟ-ferrite and is accompanied by a loss of ferromagnetism with a significant decrease in toughness and ductility. Disappearance of ferromagnetism seems to be due to the fact that ẟ-ferrite disintegrates into a σ-phase and a paramagnetic nitrogen-containing austenite. Microstructural and X-ray diffraction studies indicate that the aging of steel with ẟ-ferrite proceeds by a continuous mechanism, accompanied by a monotonous decrease in the lattice parameter of austenite due to the release of nitrides from it. Aging of two-phase steels, leading to the disappearance of ẟ-ferrite and ferromagnetism, caused a catastrophic decrease in corrosion cracking resistance.

The paper presents original experimental data on the viscosity and electrical resistivity of liquid cast irons IChKh28N2 and ICh310Kh24M2F4TR. The authors discuss the measurement results within the framework of the concept of metal melts microheterogeneity. Liquid cast iron in a micro­heterogeneous state is considered as a dispersed system consisting of dispersed Fe – 30 % Cr particles distributed in a Fe – 3 % C dispersion medium. The concept of colloidal microheterogeneity (microheterogeneity) of Fe – C melts was first formulated by Wertman & Samarin more than 80 years ago and found another confirmation in this work. The introduction of theoretical approaches to the rheology of dispersed systems into the analysis of the temperature dependences of the viscosity of microheterogeneous melts made it possible to estimate the parameters of microheterogeneity: the volume fraction and size of dispersed particles. The volume fraction of dispersed particles was determined using the Taylor equation for the viscosity of dispersed systems and size of dispersed particles – within the framework of the theory of absolute reaction rates. Analysis of the temperature dependences of microheterogeneous melts electrical resistivity within the framework of the theory of transport phenomena (in this case, conductivity) in inhomogeneous media (microheterogeneous melts) made it possible to estimate the volume fraction of dispersed particles. The volume fraction of dispersed particles based on data on the electrical resistivity of liquid cast iron was determined using the Odelevsky equation for the inhomogeneous media conductivity. The cluster size was determined by the ratio of the melt electrical resistivity at the liquidus temperature and the analysis temperature, taking into account the known data for the mean free path and the electron scattering coefficient of liquid iron. The volume fraction of dispersed particles in liquid cast iron was 0.2 – 0.1 at the liquidus temperature. With increasing temperature, the volume fraction of dispersed particles decreases. The cluster size in liquid cast iron was about 3 nm at the liquidus temperature, and with increasing temperature the cluster size decreased to 1 – 2 nm. The results obtained are of practical importance: increasing the performance properties of cast iron castings is possible by high-temperature melt treatment (HTMT) in order to change the crystallization conditions and obtain a modified structure. Studies of the microheterogeneous structure of liquid cast irons and assessment of microheterogeneity parameters make it possible to substantiate and propose the optimal HTMT mode in order to improve the performance characteristics of products made of wear-resistant cast irons alloyed with chromium.

The high demands placed on the surface quality and geometric complexity of metal products, structures and parts produced from a wide range of non-ferrous and ferrous alloys determine the demand for investment casting as a method that provides a range of critical products for the needs of aircraft, ship building and mechanical engineering industries. A number of “bottlenecks” in the implementation of investment casting processes include a significant number of technological operations, each of them is accompanied by phenomena of a thermophysical nature that require correction, and it ultimately determines the high cost of casting. The difficulties arise from phenomena such as shrinkage of the pattern material, its thermal expansion during melting from a ceramic mold, which determines penetration of pattern mass into ceramic pores and can affect the appea­rance of surface defects, the chemical composition and structure of the alloy of future casting. The process of forming a porous surface on wax patterns without shrinkage defects by pressing powders of waxy materials is aimed at eliminating the noted shortcomings, which ensures the required geometry of the compacts and absence of deformation effects on ceramics of the model material at the stage of its melting. Widespread use of the method is hampered by the lack of information about the features of stress control in the compact body determining the magnitude of elastic response of the compacted material, which is an order of magnitude less than thermal shrinkage. The paper presents the results of an experimental study of influence of the compression rate of powder materials on the stress-strain state of pressed wax patterns formed in a closed matrix, as well as on the strength of these compacts.

The paper is devoted to automatic electric arc welding under a flux layer using filler material in the form of aluminothermic backfill for joining thick-plate structures. The plate material is assumed to be elastic-plastic, the deformations are small and consist of elastic and plastic. Reversible (elastic) deformations are associated with stresses by the Duhamel-Neumann law, irreversible (plastic) ones arise and grow due to plastic flow within the framework of the associated law of plastic flow. The modified Mises condition, which takes into account viscosity, is adopted as the condition of plastic flow. The heat source from automatic electric arc welding is modeled by a double ellipsoid proposed by John A. Goldak, and heat from chemical reaction in the region of aluminothermiс combustion front is specified by the heat flux value. Elastic moduli and yield strength depend on temperature. Plates with thicknesses of 12, 14, 16, 18 mm were considered. Comparing the intensity of residual stresses in the upper and lower layers of the plates and by their thicknesses, it can be stated that with increasing thickness, the areas of distribution of residual stresses high intensity increase and their values increase too. These areas are located inside the material in the near-weld zone in the area of blue brittleness. Analyzing straightening of temperature fields, for the case of electric arc welding with filler material in the form of aluminothermiс backfill and without it, it was found that as a result of a chemical reaction, the temperature in the weld zone increases by 500 °C, this makes it possible to use this technology for welding at low climatic temperatures.

In the metallurgical industry, approximately 40 % of the energy spent on raw material preparation for further processing accounts for the processes of brittle materials destruction in crushing machines. From the analysis of operation of crushing machines, differing in the method of creating stresses in a destructible piece of brittle material, it follows that the best, from the point of view of energy efficiency, is the one in which tangential stresses (shear deformation) are generated in the processed material. The authors describe the design of a crushing machine which ensures that during the crushing process only tangential stresses arise in the piece, causing shear deformations.

The relationship between temperature-strain-force parameters in hot deformation processes is important in the forming practice. Of the two options for searching and describing such relationships (based on physical laws and mathematical techniques), in some cases the method of mathe­matical search for the desired dependence turns out to be simpler. This is exactly the path implemented in the abstracted message. For this propose, a matrix of initial data was created from digitized strain diagrams of the samples made of heat-resistant 1Cr12Ni3Mo2VNbN 12 % Cr steel deformed to a true deformation degree of ~1 at 1253 – 1453 K and a compression rate of 0.01 – 10 s^–1 in true coordinates (φ and S). In this matrix, for each point of the experimental deformation diagram the stress S, the deformation degree φ, the deformation rate φ′, and the temperature T were indicated. The required mathematical model has a multiplicative form, which made it possible to bring it into a linear form by taking logarithms and to search for coefficients with the factors (and after logarithm, with terms in a polynomial) to use standard Mathcad operators with calculation algorithms based on the least squares method. The quality of the model was assessed quantitatively by calculating Q – the sum of squared differences between the calculated and experimental stress values ​​with its normalization to the average stress value S from the entire array. For the found best form of relationship S = f (φ, φ′, T) as \(\log (S) = A + B\log (\varphi ) + C{[\log (\varphi )]^2} + D{[\log (\varphi )]^3} + E\log (\varphi ') + F\log (\varphi )\log (\varphi ') + G\frac{\varphi }{{\varphi '}} + \frac{{H + K\varphi  + M\log (\varphi ) + N\log (\varphi ') + P\log (\varphi )\log (\varphi ')}}{T}\) the Q value was 6 % of S_av = 130 MPa. It was established that the found type of mathematical description of hot deformation is applicable to the analysis of hot deformation processes of a wide variety of metal materials, while the accuracy of the predictive characteristics of the deformation stress is 3 – 11 %.