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255 results on '"Dobatkin, S. V."'

1. Low Carbon Steel Processed by Equal Channel Angular Warm Pressing

Author

Zrnik, J., Mamuzić, I., Dobatkin, S. V., Stejskal, Z., and Kraus, L.

Subjects
Low carbon steel, warm ECAP, structure evolution, dynamic recrystallization, mechanical properties, Mining engineering. Metallurgy, TN1-997
Abstract

Low carbon steel AISI 10 was subjected to a severe plastic deformation technique called Equal Angular Channel Pressing (ECAP) at different increased temperatures. The steel was subjected to ECAP with channel’s angle j = 90°, at different temperature in range of 150 - 300 °C. The number of passes at each temperature was N = 3. Light, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of thin foils were used to study the formation of substructure and ultrafine grains in deformed specimens. The size of newly born polygonized grains (subgrains and/or submicrocrystalline grains) is in range of 300 - 500 mm. The formation of such of predominant submicrocrystalline structure resulted in significant increase of yield stress [Re] and tensile strength of the steel [Rm].

Published
2007

2. Nanostructures by Severe Plastic Deformation of Steels: Advantages and Problems

Author

Dobatkin, S. V., Zrník J., and Mamuzić, I.

Subjects
nano- and submicrocrystalline structure, severe plastic deformation (SPD), equal channel angular pressing (ECAP), steels, Mining engineering. Metallurgy, TN1-997
Abstract

The aim of this paper is to consider the features of structure evolution during severe plastic deformation (SPD) of steels and its influence on mechanical properties. The investigation have been carried out mainly on low carbon steels as well as on austenitic stainless steels after SPD by torsion under high pressure (HPT) and equal channel angular (ECA) pressing. Structure formation dependencies on temperature deformation conditions, strain degree, chemical composition, initial state and pressure are considered. The role of phase transformations for additional grain refinement, namely, martensitic transformation, precipitation of carbide particles during SPD and heating is underlined.

Published
2006

21. Effect of Equal-Channel Angular Pressing and Subsequent Aging on the Structure and Mechanical Properties of Al–Mg2Si Alloys with Transition Metal Additions.

Author

Rybal'chenko, O. V., Martynenko, N. S., Rybal'chenko, G. V., Tabachkova, N. Yu., Luk'yanova, E. A., Temralieva, D. R., Tarytina, I. E., Prutskov, M. E., Ogarkov, A. I., Raab, A. G., Bochvar, N. R., and Dobatkin, S. V.

Abstract

The effect of equal-channel angular pressing (ECAP) at 150°C and subsequent aging on the structure and strength characteristics of Al–Mg2Si alloys with scandium and joint (Sc + Zr) and (Sc + Hf) additions is studied. Hardness and electrical resistivity curves demonstrate the decomposition of the supersaturated solid solution in the alloys with (Sc + Zr) and (Sc + Hf) additions is found to be same, and the optimum aging conditions of the alloys are obtained. The microstructure of the alloys and precipitation of secondary phases are studied in detail using scanning and transmission electron microscopy (SEM and TEM, respectively). The alloys subjected to ECAP and aging demonstrate an increase in the strength and the plasticity due to compensation of aging processes by recovery processes related to restructuring a dislocation structure. [ABSTRACT FROM AUTHOR]

Published
2023
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31. Effective Temperature of High Pressure Torsion in Zr-Nb Alloys

Author

Straumal Boris B., Gornakova Alena S., Fabrichnaya Olga B., Kriegel Mario J., Mazilkin Andrey A., Baretzky B., Gusak A. M., and Dobatkin S. V.

Subjects
nanocrystalline materials, high pressure torsion, phase transitions, zr-nb alloys, Technology, Chemical technology, TP1-1185, Chemicals: Manufacture, use, etc., TP200-248
Abstract

Severe plastic deformation by the high pressure torsion (HPT) leads to the phase transitions and strong grain refinement. The starting α Zr-phase in Zr alloyed by 2.5 and 8 mass% Nb transforms into β + ω mixture. This β + ω phase mixture can be found in the equilibrium phase diagram at higher (effective) temperature (Teff = 620°C for Zr-2.5 mass% Nb and (Teff = 550°C for Zr-8 mass% Nb). The published papers on phase transitions during HPT are analysed and the values of effective temperature are estimated. Contrary to the increasing temperature, the increasing pressure slows down the diffusion and grain boundary migration. Therefore, the forced atomic movement during HPT produces the states equivalent to higher temperature, but not to the higher pressure.

Published
2012
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36. Effect of Equal-Channel Angular Pressing on the Structure and Properties of Fe–Mn–C Alloys for Biomedical Application.

Author

Rybal'chenko, O. V., Martynenko, N. S., Anisimova, N. Yu., Kiselevskii, M. V., Rybal'chenko, G. V., Bochvar, N. R., Tabachkova, N. Yu., Shchetinin, I. V., Konushkin, S. V., Tokar', A. A., Ogarkov, A. I., Raab, A. G., and Dobatkin, S. V.

Abstract

The possibility of producing alloys, which are characterized by high degradation rate and used for manufacturing biodegradable implants, is studied on Fe–Mn–C alloys subjected to equal-channel angular pressing (ECAP). In particular, the attention is paid to the preparation of alloys, which have an ultrafine-grained structure and a high density of boundaries of structural elements and are in completely austenitic state. The effect of a structure on the corrosion rate, the mechanical properties, and in vitro biocompatibility has been revealed. An analysis of X-ray diffraction and transmission electron microscopy data for the alloys subjected to ECAP shows the formation of an austenitic partially or completely twin structure. The formed structure determines a high level of the strength characteristics while maintaining an adequate plasticity. As the uniformity of the twin structure and density of twin packets increases and the twin size decreases, the corrosion rate is shown to decrease. Based on results of in vitro studies of the hemolytic efficiency and cytotoxicity, the biocompatibility of the alloys subjected to ECAP is retained. The treatment conditions of samples are found not to affect their biocompatibility and to ensure a similar level of the adherence of mesenchymal cells with an osteogenic potential on the surface of the alloy samples subjected to ECAP. [ABSTRACT FROM AUTHOR]

Published
2022
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