Metallurgist最新文献

Understanding how pores form enables control over the structure and metallurgical properties of iron ore feedstock. This study pursued two objectives: (i) to test whether fractal analysis is applicable to the pore structure of iron ore pellets at different production stages (dry, indurated, and reduced), and (ii) to quantify the internal surface area of pores per unit volume. Scanning electron microscopy micrographs were acquired at multiple magnifications. The fractal dimension (D) was estimated using the box-counting (covering) method. Across image-processing workflows and magnifications, D remained within a narrow range (1.85–1.95), indicating self-similarity (scale invariance); moreover, D showed a slight upward trend with increasing image scale, further supporting the fractal nature of the pellet pore network. The internal surface area of pores with equivalent diameters of 10–100 µm was on the order of 10–100 m²/m³.

This study evaluates the influence of annular welds (undercuts) on the inner and outer surfaces of ceramic and metal casting molds on reducing their stress-strain state during the crystallization and cooling of a steel casting. Key results from a numerical simulation of parameters governing mold resistance to crack formation, specifically the magnitude of normal stresses on the inner (facing) and outer surfaces during the cooling stage of the solidifying casting are presented. The presence of annular undercuts on the inner surface of a spherical metal mold significantly reduces the level of thermal stress σ₂₂ that develops during the cooling stage of solidification, keeping it well below the maximum allowable stress level. In a ceramic shell mold featuring both cylindrical and spherical segments, substantial σ₂₂ stresses develop during casting cooling. The stresses are negative (compressive) in the inner facing layer and positive (tensile) in the outer layer at the interface with the support filler.

The shift in the transportation of crude oil, petroleum products, and LNG from the West to the East required an expansion of Russia fleet of large-capacity, deep-draft, high-ice-class tankers and the utilization of the Northern Sea Route. Annual steel consumption in Russia for shipbuilding amounts to 400,000 tons. In order to renew the outdated commercial fleet by 2031, the demand for shipbuilding steel could increase to one million tons per year if the decision is made to construct the vessels at Russian shipyards. By 2030, the demand for shipbuilding steel will reach 1.2 million tons, not including metal products for the icebreaker fleet and specialized vessels needed for navigation along the Northern Sea Route. The Zvezda Shipbuilding Complex in Bolshoy Kamen, Primorsky Krai, is the only shipyard in Russia capable of constructing large-capacity, deep-draft tankers and gas carriers from large modules. The shipyard was designed based on the principle of international cooperation. However, due to sanctions, relationships with foreign partners have been suspended. Currently, the issue of supplying the Zvezda Shipbuilding Complex with large-format steel plates produced in Russia is being addressed. Russia has three thick-plate rolling mills with reversing stands, with a combined annual production capacity of over three million tons. However, the production of high-strength steel for shipbuilding in Russia faces two main constraints. First, the continuous-cast slab is insufficiently thick to obtain wide-format plates, and the cast structure must be refined simultaneously. Second, the 5000 rolling mills lack specialized thermal units for quenching and subsequent tempering, which is necessary for producing high-strength, cold-resistant plates. Organizing the production of slabs with a thickness of at least 500 mm and equipping existing thick-plate rolling mills with quenching production capacities will significantly increase high-strength steel output for shipbuilding without the need for additional alloying. This will meet the needs of the domestic industry, which is task of national importance. This task is relevant because it ensures that Russian shipyards have the steel necessary to construct large-capacity vessels and Arctic-class marine structures.

This article addressed the optimization of the injection ring used in flash smelting furnaces (FSFs) for processing nickel-sulfide concentrates. The goal was to improve furnace performance by modifying the geometry and nozzle configuration of the injection ring. Six designs were developed, including two baseline configurations and four optimized ones, and computational fluid dynamics (CFD) simulations were carried out to evaluate their performance. A 3D model of the furnace reaction shaft was generated, incorporating baseline flow parameters and boundary conditions. The model included several simplifications: the thermal effect of methane combustion was represented as a volumetric heat source, and the gas mixture components with volume fractions below 5% were neglected. The simulations demonstrated high accuracy in reproducing gas-dynamic behavior, with a discrepancy of just 2.5%.

This study investigates the evolution of the technological ductility of a continuous-cast billet (CCB) of AISI 321 steel during rolling across various stands of a continuous pipe rolling mill. Compression, tension, and torsion tests were conducted on samples taken from the billet and shell within the temperature range of 900–1250 °C using a multifunctional complex equipped with a Gleeble 3800 thermomechanical simulation system. The results showed that the maximum ductility of billets is achieved at 1200–1250 °C and the shell at 1150–1200 °C. Preliminary deformation (piercing) was shown to improve the ductility of the billet. Ductility diagrams that consider the influence of temperature and stress state were constructed to help optimize rolling regimes and improve the pipe quality. For the first time, the obtained data enabled the rolling of austenitic stainless steel pipes directly from continuous-cast billets at the Volzhsky Pipe Plant.

We present various procedures capable of improving the quality of strips by means of increasing the efficiency of control over the cross-sectional profile of the strip. We consider the techniques designed both by domestic and foreign researchers. In this case, various methods are used to improve the quality of strips: design of the shape and structure of the rolls, position of rolls in the stand, application of the finite-element method (FEM) for the computer simulation, the use of various components of artificial intelligence: neural networks, broad range of optimization algorithms, digital twins, machine learning, etc.

Formation of microstructures in 25Kh2N4MA high-strength steel during heat treatment was investigated. Using the dilatometric method, the temperature ranges for the formation of bainite and martensite during continuous cooling at rates from 0.1 to 30 °C/s were determined, and the corresponding continuous cooling transformation (CCT) diagram for the transformation of undercooled austenite was constructed. The mechanical properties were found to vary depending on quenching intensity and tempering temperature. The kinetics of isothermal bainite transformation were analyzed, and the level of properties achievable through bainite formation in different temperature ranges was determined. The presence of bainite in 25Kh2N4MA steel was shown to result in a 20–25% increase in impact toughness compared to the martensitic structure formed by oil quenching and low-temperature tempering. A quantitative assessment of the structural components in the steel after various heat treatments was performed.

This paper presents the design and validation of an intelligent hardware–software system for automated pipe counting in continuous production. The solution employs a two-stage neural-network architecture based on the YOLOv8 model and implemented as a two-stage architecture that first localizes the region of interest (RoI) and then performs high-precision pipe detection. The system integrates robust image acquisition, adaptive processing algorithms, and real-time data handling to ensure accuracy and stability under industrial conditions. Both software and hardware components are described in detail. Field trials confirmed high performance, achieving a precision of 99.3%, recall of 99.7%, and an F1 score of 99.5%. The system contributes to the digitalization of quality control and improves the efficiency of pipe manufacturing operations.

We study, the environmental impact of metallurgical production in the Irkutsk region by focusing our attention on the PJSC “RUSAL Bratsk” plant. Under the conditions of economic uncertainty caused by the world crisis and sanctions, metallurgy continues to exert a significant negative influence both on the ecosystem and on the health of local population. We investigate the possibility of secondary use of fine-fraction dust wastes (electrofilter dusts and sludges) formed in the process of production with an aim to weaken harmful ecological effect. The performed evaluation of the degree of damage to atmospheric air and soils demonstrate that the PJSC “RUSAL Bratsk” is responsible for 61% of emissions of the harmful substances in the regions of its operation. Our investigations revealed the presence of a high level of ecological damage, strongly affected by the wastes of hazard classes 3 and 4. Therefore, the main efforts in our work are concentrated on the use of these wastes as secondary raw materials in manufacturing of sorption materials, which would make it possible to reduce the volume of nonrecyclable wastes. The results of comparative analysis demonstrate that the obtained sorbents are characterized by good physicochemical properties and high resistance to the action of microorganisms, which opens wide prospects for their application in wastewater treatment. The accumulated results emphasize the necessity of implementation of measures aimed at the reuse of metallurgical wastes as a method for minimizing their negative impact on the environment.

The tailings storage facilities of mining and metallurgical complexes hold approximately 100 billion tons of solid waste, which can serve as raw material for extracting residual metals left after primary processing. The current practice of disposing these tailings into mined-out spaces leads to the loss of valuable components and effectively transforms the region into a natural reactor for metal leaching. This study aims to elaborate the concept of resource conservation specifically for the conditions of the Kursk Magnetic Anomaly (KMA). The paper presents a comprehensive overview involving analysis, systematization, experimentation, modeling, techno-economic calculations, and engineering forecasts. Data on the leaching rates of beneficiation tailings are also provided. The results demonstrate that maximum metal recovery is achieved through mechanochemical activation of the leaching process. Therefore, a waste-free processing flowsheet incorporating this mechanochemical activation is presented. It is recommended that a comprehensive flowsheet be used for the deep processing of technogenic raw materials to extract valuable components. Research has shown that milling tailings into a fine powder allows for the production of backfill mixtures with a strength of 6–10 MPa. After metal extraction, the beneficiation tailings can be used as a component of these mixtures and as binders. The study also confirmed that activation increases the strength of the mixtures. A nomogram was developed to determine the strength of artificial structures. After metal recovery, tailings are suitable for concrete production with reduced cement consumption. The study determined that mechanochemical activation of tailings in a disintegrator allows the mixture to meet required specifications two orders of magnitude faster than agitation leaching. The results of an economic efficiency calculation for processing tailings with mechanochemical activation are presented as well.