Кафедра ливарного виробництва (ДМетІ)

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ENG: Department of casting production (DMetI)

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Complex Solid-Phase Reduction in a Blast Furnace of Self-Healing Pellets of Cold Agglomeration Containing By-Product Carbon Materials of Metallurgical Production
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Vaniukov, Anton A.; Ivashchenko, Valerii P.; Ivanova, Liudmyla Kh.; Kovalov, M.; Tsybulia, Ye.
ENG: The reactions of direct and indirect reduction occurring during the heat treatment of self reducing pellets (SRP) have been studied. In this investigation Blast furnace (BF) sludge which contains particles of coke, has been included in the SRP blend as a source of solid reductant. In the SRP as a part ot the blast furnace burden occur the reactions simultaneously: inside of SRP-direct reduction by Csolid; gasification of carbon and indirect reduction by CO; and outside of SRP-indirect reduction of iron bearing oxides by reducing gas coming from the hearth of blast furnace through the column of charged materials. The experiments was performed continuously from the start temperature (~200 ˚C) to the experimental temperature (500 ˚C; 700 ˚C; 900 ˚C; 1100 ˚C) in argon free environment. Upon reaching the desired temperature argon was replaced by hydrogen during 30 minutes. After that the reduced probe of SRP was cooled in argon. The objective of the present work is to research a quantitate ratio of degree direct reduction inside of SRP and degree of indirect reduction outside of SRP on the top of the blast furnace.
Heat Balance of Billets during Hot Extrusion of Nickel Alloy Pipes
(Ukrainian State University of Science and Technologies, Dnipro, 2026) Medvedev, M. I.; Bobukh, Oleksandr S.; Kuzmina, O. M.; Krasiuk, A. D.; Ivanova, Liudmyla Kh.
ENG: Among the problems encountered in the production of nickel-based alloy pipes by hot extrusion sleeves on horizontal hydraulic presses, one of the main ones is the high level of product surface defects. To reduce rejects on this basis, it is important to understand the changes in the temperature field of the pipe billet throughout the entire technological process, since this factor is the key to the formation of surface defects in such pipes. The purpose of the work is to establish the regularities of temperature changes in nickel alloy pipe billets at the main stages of pipe production, which are made by extrusion on presses with a force of 16.0 MN and 31.5 MN with the use of glass lubricants. Methodology. The work was performed based on the results of a systematic analysis of the main technological stages of the actual process of producing hot-extruded pipes made of nickel alloy 602CA on presses with a force of 16.0 MN and 31.5 MN. The selected production stages include: transporting the billet (liner) from the induction heater to the glass-filled table, applying glass-filled material to the billet surface, transporting the billet with glass-filled material to the press, holding the billet in a container before extrusion, and extrusion in the container. The calculation of the stepwise temperature loss by the billet was performed using known and own empirical equations obtained from the results of thermography of the billets. The chemical composition of the billets was determined using an Elvax plus spectrometer. The temperature of the outer surface of the workpiece was measured using chromium-aluminium thermocouples complete with an electronic potentiometer. Results. It was found that the total change in the temperature of the sleeves during the cooling process during auxiliary operations on presses with a force of 16.0 MN and 31.5 MN at the same initial heating temperature of the workpieces is inversely proportional to their wall thickness. At the same time, this dependence is almost linear in the range of 40...120 mm wall thickness of the sleeves and 1050...1250 °C heating temperatures of the workpiece. Scientific novelty. For the first time, a methodology for calculating the temperature of the sleeves at the main stages of their preparation for the extrusion process has been developed. Practical utility. The use of the developed methodology for calculating the temperature of the liner allows for a reasonable choice of glass lubricant for the initial technological operations of extrusion on presses with a force of 16.0 MN and 31.5 MN using glass lubricant, which in turn contributes to improving the surface quality of pressed pipes, reducing the level of pipe rejects and reducing the volume of their the volume of their further mechanical processing.