Перегляд за Автор "Pashynska, O. H."

Зараз показуємо 1 - 4 з 4

Forming of properties complex of copper wire by the method of combined deformation by torsion and tension
(ПП "ТЕХНОЛОГІЧНИЙ ЦЕНТР"; Полтавський державний аграрний університет, 2022) Pashynska, O. H.; Pashynskyi, V. V.; Kraliuk, M. O.; Boyko, I. O.; Пашинська, О. Г.; Пашинський, В. В.; Бойко, І. О.; Кралюк, М. О.
The object of research is the mechanical properties of copper wire M1 for electrical applications, subjected to combined torsional deformation with tensile tension. One of the most problematic aspects in the manufacturing of such a wire is its fracture during processing due to low strength and ductility. DSTU EN 13602:2010 regulates the ultimate tensile strength, relative elongation, the number of bends before fracture and the number of twists until failure. To increase the service life of the product it is necessary to increase strength and plastic properties.The methods of influence on the material by combined plastic tensile deformation with tensile was used in the study, the mechanical characteristics (ultimate tensile strength, true deformation before failure, relative elonga-tion, relative reduction in area) and electrical conductivity were determined. Statistical analysis tools were used for modeling and graphical displaying of data.The proposed approach allows to select the modes of combined torsional deformation with tensile, providing the optimal combination of tensile strength and relative narrowing of M1 grade copper wire. Under certain modes of such deformation, with increasing degree of deformation, it is possible to increase the strength characteristics and at the same time obtain high values of plasticity.The obtained results of approbation of different combined deformation modes allow to consider it an effec-tive tool for achieving high values of true rapture stress and ultimate deformation in order to improve the service characteristics of the deformed wire. It is shown that relaxation processes occur during such treatment, which leads to a decrease in stresses and a sharp increase in plastic characteristics. Clarification of the mechanisms of the characteristics formation allows to control the features of the structure and, accordingly, the level of mechanical properties to obtain a wire that combines high strength with high toughness. This makes it possible to develop de-formation modes to obtain copper wire with special properties depending on customer requirements, for example: strong wire with low electrical resistance.
Influence of heat treatment on the structure and wear resistance at abrasive wearing of high-carbon chromonickel steel of 150H15N5VM type
(Фізико-технологічний інститут металів і сплавів НАН України, 2023) Pashynskyi, V. V.; Pashynska, O. H.; Boyko, I. O.; Пашинський, В. В.; Пашинська, О. Г.; Бойко, І. О.
The article is devoted to the improvement of heat treatment regimes of steel 150H15N5VM type to ensure the necessary operational characteristics of the tool. The wear resistance of the alloys during abrasive wear was studied by the method of friction against a fixed abrasive. Formation of different structural states was performed by annealing of cast steel at temperatures of 550–900 °C, as well as quenching from temperatures of 950–1100 °C, followed by tempering in the range of 550–850 °C. The structure of the steel was studied by optical metallography and the morphology of the wear surfaces – by scanning electron microscopy. As a result of research, it was established that high-chromium steel with nickel addition in the cast state has increased stability of retained austenite. To obtain maximum hardness, cast steel should be heated in the temperature range of 740 ... 790 °C for 2 ... 4 hours. As a result of annealing and following quenching with tempering, two variants of the structural state with increased wear resistance are formed – martensite and retained austenite immediately after tempering and the products of tempering of martensite and decay of retained austenite at high tempering. Wear resistance increases with increasing of quenching temperature. The main mechanism of wear is microcutting of the surface by hard abrasive particles. The drop in wear resistance at tempering temperatures of 550–650 °C is a consequence of a decrease in hardness and is accompanied by changes in the micromechanism of the wear surface destruction – the appearance of local centers of destruction. A significant increase in wear resistance with a further increase in tempering temperature, especially at small specific loads, can be explained by the formation of special carbides of alloying elements in the matrix.
Shear impact during steel wire drawing on grain boundaries and mechanical properties
(Institute for Metals Superplasticity Problems of Russian Academy of Sciences, 2020) Zavdoveev, A. V. ; Baudin, Т.; Rogante, М.; Pashynska, O. H. ; Skoryk, M.; Пашинська, О. Г.
Shear deformation is one of the effective ways for grain boundary engineering. In the current contribution, the effect of the shear deformation incorporated into the conventional drawing process is shown. A specific feature of this experimental technology is a reduction of the structural anisotropy. This effect is related to the application of dies with shear that makes the metal flow to change its direction. In particular the grain refinement is stronger. The experimental drawing technology results in an extensive increase in the fraction of small grains (less than 3 μm in size) and a decrease in the fraction of large grains. A large amount of small grains with high-angle boundaries in this case is registered. The formation of this kind of grains is explained by progress in competing processes of large grain fragmentation and continuous dynamic recrystallization. The result is the change of the type of the grain boundaries from smooth to serrated ones and the formation of unclosed high-angle grain boundaries. Besides, it has been demonstrated that a certain part of small grains provides grain boundary sliding. The comparative analysis of the hardness tests has demonstrated increasing hardness with deformation accumulation, but after the classical drawing, the hardness grows linearly and stepwise after the experimental shear drawing. The physical reasons of such behaviour are explained by microstructural features which are discussed in current contribution.
Small Angle Neutron Scattering Study of Nanoscale Structure of Low-Carbon Steel After Rolling with Shear Followed by Cold Drawing
(Корейський інститут металів і матеріалів, 2021) Zavdoveev, A. V.; Len, A.; Pashynska, O. H.; Пашинська, О. Г.
Small angle neutron scattering was applied to steel produced by rolling with shear (RS) technology and compared to samples produced by standard technology (ST). Based on small angle neutron scattering measurements the morphology of the grains and pores of RS steels were compared to those of the ST steels. The scattering in small scattering vector region showed anisotropy, attributed to the elongation of the pores; the pearlite lamellae distances along and perpendicular to the rolling directions difered by a factor of 1.5. The results of the Small angle neutron scattering measurements were in accordance with the electrical characteristics of the specimens. They showed smaller and less anisotropic average sizes of the cracks and nanopores for the RS samples than for the ST rods. This confrms the dynamic healing of the nanosized defects during the cold drawing of the RS rods. This fundamental result shows that during severe plastic deformation a cyclic process of nucleation and healing of the nanovoids took place. However, during the standard deformation process only nucleation of the nanovoids is present.