Metallurgist最新文献

Nanostructured powders of AMg6 deformable aluminum alloy are obtained by the procedure of high-energy ball milling of chips. The structures and properties of these powders are characterized by the methods of scanning electron microscopy, X‑ray diffractometry, granulometric analysis, and kinetic indentation. We determine the mechanism of transformation of chip materials including the procedure of deformation of the original chips into flake-like particles and their subsequent fragmentation down to the formation of powder particles. The influence of the conditions of mechanical treatment in a planetary mill on the granulometric composition of the obtained powder mixtures is studied. The possibility of grinding of the chips of aluminum alloy in a steel working chamber with the help of steel bodies carried out without noticeable contamination of the powder material with iron impurities is established. The quantitative data on the contents of aluminum oxide in powders are obtained. It is shown that, for the obtained powders, the mean size of the regions of coherent scattering constitutes ~89–115 nm. It is also demonstrated that the procedure of high-energy ball milling of chip wastes leads to an ~1.8–2-fold increase in the level of microhardness of the obtained powder particles as compared with the chip material.

Physical properties of steels exhibiting TRIP-TWIP effects were measured in order to use the obtained data for calculations relating to steel casting regimes in slab vertical continuous casting machines, and to develop casting technology. Specifically, coefficient of the linear thermal expansion was measured in the temperature range of 100–700 °C, alongside the solidus and liquidus temperatures, density, and specific heat capacity in the range of 20–1500 °C. The thermal diffusivity and thermal conductivity of steels alloyed with Si, Cr and Ni, as well as steels containing 14.5 and 7.40 wt % Mn, were also determined. These results will refine the calculations of parameters for the continuous casting, rolling, and forging of the investigated steels, as well as other production processes.

A technological scheme for vacuum-thermal decarburization (VTD) of high-carbon ferrochrome (HC-FeCr) was developed based on preliminary research and existing production methods. Optimal conditions for grinding, oxidation, briquetting, and drying were determined through experimental studies. The kinetic parameters of the VTD reaction for HC-FeCr were identified using thermal analysis. Combined with thermodynamic calculations, these parameters enabled the proposal of optimal VTD conditions (temperature, pressure, and process duration).

The structure and phase composition of coatings formed on the surface of the CrNi32Ti alloy by the hot-dip aluminizing method with subsequent heat treatment were studied. During aluminizing of the CrNi32Ti alloy, a continuous coating is formed on its surface, consisting of an aluminum matrix with eutectic regions ((Al)+τ₁(FeNiAl₉)), large intermetallic inclusions of the H‑(CrFeAl) phase and interlayers of FeNiAl₅ and FeAl₃(Cr) intermetallic compounds along the substrate interface. The heat treatment of the aluminized CrNi32Ti alloy at 1100 °C ensures the dissolution of aluminum-rich intermetallic compounds and the formation of aluminide (Fe,Ni,Cr)Al in the surface layer. High-temperature oxidation of the resulting coatings is accompanied by the formation of a stable α‑Al₂O₃ and metastable θ‑Al₂O₃ phases on their surface.

This paper presents a parametric analysis methodology for supervisory control of the electrolytic copper refining process. The approach employs an antisymmetric dynamic regulator to compensate for deviations in key process parameters, including electrolyte composition, current density, and circulation rate. The developed mathematical model captures the input–output relationships of the system, enabling precise prediction and adjustment of operating conditions. Modeling was conducted to assess the influence of sulfuric acid concentration, copper content, and electrolyte circulation rate on productivity and current efficiency. The results demonstrate that the proposed method effectively mitigates disturbances, stabilizes current efficiency, and maintains productivity within target ranges. Additionally, the identification of optimal operating ranges contributes to improved energy efficiency and reduced material consumption. The model’s integration into a SCADA-based control system enables real-time monitoring and high responsiveness, enhancing both operational reliability and adaptability.

The influence of the roller table level on the vertical bending of the leading edge during asymmetric thick-plate rolling has been investigated using finite-element modeling. The study demonstrates that a mismatch in the rotational speeds of the work rolls can produce inconsistent deformation patterns, causing the strip to bend toward either the slower or the faster roll. A finite-element model developed in the Deform software was employed to simulate the bending behavior of K60-grade pipe steel strips under various asymmetry conditions. The results show that for strip thicknesses of 25–50 mm, a mismatch between the roller table level and the rolling line leads to upward bending of the leading edge. This effect is amplified when the lower roll rotates faster than the upper roll and the reduction is below a critical threshold. To mitigate vertical bending, intentional counterbending can be induced by adjusting roll speed asymmetry. In doing so, it is necessary to account for the critical reduction or the deformation zone shape factor, defined as the ratio of the deformation zone length to the average strip thickness.

Experimental studies of the forced capillary disintegration of a system of jets of molten lead were carried out. It has been shown that increasing the number of dispersed jets makes it possible to increase the productivity of the process by an order of magnitude. At the same time, the high quality of monodisperse spherical granules is preserved. The main patterns of the influence of oxidation of the surface of a liquid metal jet on the process of its disintegration have been studied. Obtained results can be used later to expand the functionality of monodisperse granulation technology.

We present a version of implementation of the physical modeling of the processes running in the course of production of transformer steels in all stages of the process after hot rolling. We consider various types of installations applied for this purpose throughout the world and analyze the advantages and disadvantages of their application. The requirements for the set of equipment are specified and a criterial assessment of the implementation options is carried out. The results obtained in the work make it possible to realize the possibility of acceleration and improvement of the quality of development of new grades of transformer steels.

Synthesis of composite materials by the method of selective laser melting based on a metal matrix with improved properties is actual and extensively developed direction of scientific research. The development of aluminum-matrix composites and their adaptation to the technology of selective laser melting requires taking into account numerous critical factors, such as the composition of the composite, the method used for the preparation of the source powder material, conditions of synthesis, etc. In the present work, we analyze the role played by the main factors in the development and synthesis of aluminum-matrix composites, the processes running in the melt pool during synthesis, and the key problems and tasks encountered in this field. On the basis of the deep analysis of data available from the literature, we determine the main trends in the subsequent development of the procedure of synthesis of aluminum-matrix composites by the method of selective laser melting, among which we can mention the development of aluminum-matrix composites accompanied by the formation of new phases as a result of the in situ reactions in the melt pool, computer simulation of the process of synthesis of aluminum-matrix composites, and the implementation of the in situ control over the process of melting by using various methods with a possibility of affecting the conditions of synthesis by using the accumulated data. We also formulate the tasks and fields of scientific investigations that require solutions and further efforts of the scientific community aimed at improving the properties of the aluminum-matrix composites.

The structure and properties of sheet steel produced from low carbon martensitic steel using various controlled rolling regimes was investigated. Standard mechanical properties, ductility parameters, and steel toughness were determined. The effects of the temperature range and the final deformation temperature during the finishing stage of rolling on the structure and consequently on the strength properties, cold resistance, and fracture resistance of the rolled steel were investigated. The study reveals the relationship between the processing regime and the level of steel properties. The results indicate that reducing the final deformation temperature improves low-temperature impact toughness and increases the proportion of crack propagation work in the total fracture energy.