Кафедра "Прикладна механіка та матеріалознавство" <br> (з 2016 року об'єднано каф. "Прикладна механіка" та каф. "Технологія матеріалів")
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RU: Кафедра "Прикладная механика и материаловедение" с 2016 г. объединены каф. "Прикладная механика" каф. "Технология материалов"
EN: Department of Applied Mechanics 2016 Department of Applied Mechanics Department of Material Technology
EN: Department of Applied Mechanics 2016 Department of Applied Mechanics Department of Material Technology
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Browsing Кафедра "Прикладна механіка та матеріалознавство" <br> (з 2016 року об'єднано каф. "Прикладна механіка" та каф. "Технологія матеріалів") by Subject "aluminum alloy"
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Item Concept of Determining the Friction Stir Welding Mode(Національний гірничий університет, Дніпро, 2018) Vakulenko, Ihor O.; Plitchenko, Serhii; Murashova, Nataliia H.; Bohomaz, Volodymyr M.ENG: Purpose. To determine the optimal mode of friction stir welding of aluminum alloy. Methodology. 2.5 mm thick plates made of aluminum alloy AMg5 with chemical content of alloying elements within grade composition were used as a material for the research. Friction stir welding was carried out using specially designed equipment with a preselected form and dimensions of working tool. At different ratios of the working tool rotation frequency the forces of pressing and speed of its movement along the connecting edges determined the metal heating degree and the quality of welded joint formation. Temperature of the connecting edges heating was determined by thermocouples immersed in metal at different distances from the welded joint. Rotational speed of the working tool was from 800 to 1600 min-1 with the effort of pressing to the plate surface from 580 to 1370 N and the speed of movement along the joint of 50 mm/min. Findings. On the basis of different ratios of the working tool rotation speed and pressing to the connecting edges, there were determined conditions for achieving the effect of constant softening during friction stir welding. In order to achieve a high level of welding joint quality during friction stir welding it is necessary to carry out the process at high revolutions of the working tool and low levels of pressing to the connecting edges. Originality. At the constant speed of the working tool rotation proportional increase in alloy temperature from increasing the level of its pressing to the connecting edges is disturbed by achievement of conditions of the dynamic softening processes development. Practical value. The concept of choosing the technological parameters of welding process is determined, when it is preferred to increase in speed of the working tool rotation when the level of its pressing to the connecting edges decreases.Item Determination Activation Energy of Friction Stir Welding(WRTYS, Kyiv, 2017) Vakulenko, Ihor O.; Plitchenko, SerhiiEN: According to the technology of friction stir welding (FSW) heating of the edges is equal to 0.85-0.9 from the melting temperature of metal (T). Increase in temperature is accompanied by increased degree of the metal stirring, which leads to ambiguous influence on the metal density and concentration of cavities at different distances from the welding joint. At the same time, the temperature gradient across the section of joint leads to a different speed of recrystallization processes development and forming of structural heterogeneity in metal edges. Thus, the relevant question is to determine the optimal scheme of metal edges heating during the implementation of FSW technology. Material for the study was alloy AMg5. For different ratio of rotation speed and pressure on operating tool there were obtained the conditions of superplastic state of alloy at the temperatures of heating at the level of 0.45-0.5 from T, which corresponds to the beginning of dynamic recrystallization development during FSW. At the same time, it was evaluated the energy of activation (EA) of FSW process. Using the analysis of the obtained results it was determined the fact that when reaching the same temperature of alloy heating the EA value of FSW process decreases with increasing the rotation frequency of the operating tool and decreasing the degree of its pressing to the edges of welding joint. On the basis of the above mentioned the development of FSW technology should be directed toward the use of high speed rotations of the operating tool and low levels of its pressing to the alloy edges.Item Use of Electric Pulse Treatment for Relaxation Internal Stresess(DIA Ltd, Kyiv, 2017) Vakulenko, Ihor A.; Plitchenko, Sergey; Sokirko, V. A.; Nadegdin, Yurii L.; Efremenko, Vasiliy G.EN: The article deals with explanation of the effect redistribution of residual stresses after processing electrical pulses based on aluminum alloy after welding. The results indicate quite significant influence of electrical pulse treatment on both the morphology of alloy structural components and the relation of chemical elements involved in the formation of certain phases alloy. After the welding alloy had the majority of the signs of the cast condition with characteristic plate forms of the eutectic components. The use of EP has led to the quite significant qualitative changes in the internal structure. The globular structures formation indicates a high degree of EP influence on the development of structural change processes. Studying the chemical composition of the phase components was found out that the observed structural changes of alloy as a result of EP first of all may be caused by the redistribution of chemical elements, which form the compounds themselves. After the EP of the welded joint, the alloy hardness increase is accompanied by the decrease in the number of crystal structure defects and coarsening of the coherent scattering regions.