OBRABOTKAMETALLOV Vol. 24 No. 2 2022 TECHNOLOGY Fig. 10. Changes in tensile strength and elongation of specimens during the tensile testing Conclusions As a result of the theoretical and experimental studies, the following conclusions can be drawn: 1. An optimal place for ultrasonic vibration application and welding the seam is one of the maximum amplitudes of self-induced bending vibrations of the welding plate. The weld joint length is selected based on the equality of the resonance frequency of self-induced vibrations and the frequency of the vibration source; 2. The nature of plate vibrations depends on the processing conditions defi ned by the vibration amplitude. The highest proportion of bending vibrations is achieved in intermediate conditions of vibrations; 3. The application of ultrasonic vibrations leads to changes in the weld metal microstructure, which is expressed in a signifi cantly reduced proportion of dendritic segregation; 4. The introduction of ultrasonic vibrations reduces the crystallization start temperature, increases the number of nuclei formed, and decreases its growth rate; 5. The mechanism of changing the microstructure is the dispersion of dendrites and crystallization nuclei when cavitation bubbles collapse. Dendrite fragments are the new nuclei of crystallization that propagate through the processed volume due to acoustic streams. Then the process is repeated; 6. In a welded joint, the formation of which was accompanied by the applying of ultrasonic vibrations, welding deformations decrease, and ultimate strength and plasticity increase. References 1. Wang H., Cen S. Research on microstructure and mechanical properties of CMT and MIG welded joints of A6N01 aluminum alloy. Journal of Physics: Conference Series, 2022, vol. 2185, iss. 1, p. 012051. DOI: 10.1088/1742-6596/2185/1/012051. 2. Sundukov S.K., Nigmetzyanov R.I., Fatyukhin D.S. Structure of the weld formed during the application of ultrasonic vibrations. Russian Metallurgy (Metally), 2021, vol. 13, pp. 1667–1672. DOI: 10.1134/ S0036029521130309. 3. Prikhodko V.M., Karelina M., Sundukov S., SukhodolyaA., Moiseev V. Improvement of operational properties of parts permanent joints with ultrasound technologies use. Journal of Physics: Conference Series, 2019, vol. 1353, iss. 1, p. 012081. DOI: 10.1088/1742-6596/1353/1/012081. 4. Babchenko N.V., Seliverstova O.V., Sundukov S.K., Fatyuhin D.S. Povyshenie ekspluatatsionnykh svoistv svarnykh shvov ul’trazvukovymi metodami [Improving operational properties weld the ultrasonic method]. Vestnik
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