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Browsing Статті КПММ by Author "Askerov, Hangardas"
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Item The Calculation of Stress Intensity Factor Steel of Railway Wheels(Silesian University of Technology, Katowice, Poland, 2020) Vakulenko, Ihor O.; Proydak, Svetlana V.; Askerov, HangardasEN: From an analysis of the dependence complex of carbon steel properties on structural parameters, it was found that for an isostructural state, the influence of austenite grain size on impact strength exceeds the dependence on carbon content. As a result of explaining correlation relationships between individual mechanical characteristics, to evaluate critical stress intensity factor, a relationship is proposed based on the use of impact strength. The proportionality coefficient in proposed dependence is determined by ratio of elongation to narrowing at tensile test.Item The Effect of Stress Pulses on the Cyclic Endurance of Steel Axle Wheel-Set(Nevsehir Haci Bektas Veli University, Cappadocia, Nevsehir, Turkey, 2019) Vakulenko, Ihor A.; Bülent, Kurt; Raksha, Serhii V.; Askerov, Hangardas; Hryshchenko, Mykola A.ENG: For different temperature and speed deformation conditions, the nature of the increase in the number of defects in the crystal structure and the achieved complex of properties are due to the peculiarities of the internal structure of the metallic material. Compared with unidirectional static loading, the violation of the monotonous nature of the effective stress is accompanied by qualitative changes in the internal structure of metals and alloys. Thus, the pulsating nature of the acting stresses in case of fatigue, depending on the degree of cyclic overload per cycle, can lead to significant changes in the development of the processes accumulation and redistribution of defects in the crystal structure and, above all, dislocations. Based on this, the rate of accumulation of dislocations per loading cycle can be considered as one factor that will allow the development of measures to increase the cyclic endurance of metallic materials during fatigue. Compared to thermal technologies, treatments that are based on the use of short stresses pulses for moving defects in a crystal structure have gained some fame. In addition to sufficiently strong magnetic fields or high-power pulses of electric current, treatments based on mechanical effects on the metal can be used.Item Formation of Carbon Steel Structure During Hot Plastic Deformation(Dnipro National University of Railway Transport named after Academician V. Lazaryan, Dnipro, 2020) Vakulenko, Ihor O.; Bolotova, Daria M.; Proidak, Svitlana V.; Askerov, Hangardas; Cug, H.; Tchaikovska, H. O.EN: Purpose. The main purpose of the work is to determine the peculiarities of the development of recrystallization processes of carbon steel austenite depending on the degree of hot plastic deformation and to develop proposals for improving the structural state of the metal of the railway solid-rolled wheel. Methodology. Two carbon steels of a railway wheel with a minimum and maximum carbon content of 0.55 and 0.65 % and other chemical elements within the grade composition of the steel 60 were used as research material. Samples in the form of cylinders with a diameter of 20 mm and a height of 40 mm were heated in a muffle furnace, exposed for a certain time to equalize the temperature across the cross section of the sample. After that, the samples were subjected to hot compression on Instron type test machine. The temperature interval of hot compression of the samples was 950–1100 ºС, with deformation degrees in height in the range of 10–40%. The strain rate was 10-3–10-2 sec-1 . A standard etching was used to detect the boundaries of the austenite grains. Structural studies were performed using Epikvant type light microscope at magnifications sufficient to determine the structure of austenite grains. The grain size of austenite was determined by the methods of quantitative metallography. Findings. In the case of hot compression of the railway wheel blank, increasing the concentration of carbon atoms only within the grade composition of the steel is sufficient to increase the average austenite grain size, which confirms the proposals to limit the carbon content in the metal of railway wheels. The formation of a certain degree of austenite structural heterogeneity at the cross section of the rim or hub of the railway wheel is due to a change in the development mechanism of recrystallization processes depending on the deformation value. Under conditions of the same degree of hot plastic deformation, the replacement of one-time compression by fractional one is accompanied by a violation of the conditions of formation of the recrystallization nucleus. As a result of the specified replacement of the scheme of hot plastic deformation we obtain reduction in the austenite grain size. Originality. Based on a study of the development of collective recrystallization processes during the hot compression of carbon steel of the railway wheel, it was determined that the increase in carbon content contributes to the austenite grain increase. After hot compression of the wheel blank, the structural inhomogeneity of austenite that occurs is determined by a change in the mechanism of recrystallization processes development. During deformations above the critical degree, the recrystallization nuclei are formed and successively grow, which leads to the structure refinement. In the case of deformations below the critical value, the growth of austenite grains occurs according to the coalescence mechanism, according to which fragments of boundaries with large disorientation angles consistently disappear. Practical value. For austenite grain refining in massive elements of solid-rolled railway wheel we offer to replace one-time hot compression by fractional one.Item Influence of Plastic Deformation Carbon Steel on the Process of Burning lectric ARC(Silesian University of Technology, Poland, 2021) Vakulenko, Igor A.; Plitchenko, Sergey; Kurt, Bulent; Askerov, Hangardas; Proydak, Svetlana V.; Erdogdu, Ahmet EmrahEN: During a study of the combustion process of a direct polarity electric arc, a directly proportional dependence of the electric current value on the degree of cold plastic deformation of carbon steel used as an electrode was found. To calculate the value of the electric current during arc burning, in the indicated ratio, it was proposed to replace the surface tension force of the liquid metal with the surface tension of ferrite of plastically deformed carbon steel. Calculation of the ferrite’s surface tension value on the deformation degree of the steel under study through the size of the coherent scattering regions was used to explain the observed dependence of the electric current during arc burning. From the analysis of the considered correlation ratios, it was found that with an increase in the cold deformation degree, the refinement of the coherent scattering regions results in the ferrite’s surface tension increase and consequently, to an increase in the electric current during arc burning. Comparative analysis of the obtained results of calculating the value of electric current during arc burning through the surface tension of ferrite of cold-deformed carbon steel showed a fairly good coincidence with experimental data. The differences did not exceed 9%.Item Insights into Factors of Damage of Surface Rolling of Railway Wheels During Operation(The Silesian University of Technology, 2019) Askerov, Hangardas; Vakulenko, Igor A.; Grischenko, NikolajiEN: The systematization results of microstructure studies of carbon steel has made it possible to explain the mechanism of formation of certain damages to the rolling surface of railway wheels during operation. The evaluation ability of metal to strain hardening was used to explain the nature of the influence compactly located non-deformable dispersed particles on the strength properties steel during cold plastic deformation. In the process of the interaction of a railway wheel with a rail, successively occurring heterogeneities in the distribution of the plastic flow metal are one of the main reasons for the formation of defects on the rolling surface of the wheel.Item Transformation of Structure During Friction Stir Welding(Silesian University of Technology, Poland, 2021) Vakulenko, Igor A.; Plitchenko, Sergey; Kurt, Bulent; Proydak, Svetlana V.; Askerov, HangardasEN: In comparison with low carbon steels, there is increased interest in the use of aluminium-based alloys as materials for the manufacture of welded structures rolling stock of railway transport. During friction stir welding aluminium-based alloy, against the background of the analysis structural transformations, issues of development hardening processes are considered. Under conditions of existence, a temperature gradient at zone of weld formation, shown degree approximation alloy to the conditions of superplastic flow and influence from presence particles of the second phase on grain size of matrix is estimated. Evaluation of the separate influence grain size of matrix and state of solid solution at total hardness of the weld showed dependence of their contributions on temperature of hot plastic deformation. As the temperature of plastic deformation of alloy at area of the weld increases, contribution to the total hardness from grain size increase and on state of the solid solution decreases.