Moscow Polytechnic University, Moscow, Russia

V. V. Ovchinnikov, Head of the Department of Materials Science, Doctor of Technical Sciences, Professor, vikov1956@mail.ru
М. А. Barykin, Research Engineer, mr.barykin97.97@mail.ru
R. B. Reztsov, Postgraduate Student of the Department of Materials Science, anikron_91@mail.ru
I. S. Solovev, Research Engineer, solovev.i.s@yandex.ru

The study results of the structure and properties of welded joints of an experimental aluminum alloy of the Al – Zn – Mg – Ca system obtained by singlesided friction stir welding (FSW) are presented. Hot-rolled sheets and cast blanks with a thickness of 5 mm have been used. Optimal technological welding modes (FSW): the tool rotation speed is 850–900 rpm and the speed of its movement is 95–150 mm/min, the angle of the tool inclination in the plane of the welded joint is 2.5^о with a clamping force to the welded sheets of 2.2–2.8 kN. The study results have confirmed the absence of influence of the cast blanks location relative to the direction of the tool rotation on the mechanical properties of welded joints. The strength coefficient of the weld relative to the cast blank is 0.99–1.0, relative to the hot-rolled one is 0.71–0.72. The bending angle is in the range of 44–50^о. It is established that the lowest hardness values coincide with the area of thermomechanical action from the cast blank. Analysis of the fine structure of the welded joint has revealed the formation of a dispersed grain structure with an average grain size of about 1–3 microns. In an alloy containing small additives of Zr and Sc, L12 type nanoparticles with a diameter of about 1-3 microns have been found in the grains of the aluminum matrix. The prospects of the friction stir welding method for obtaining high quality joints of blanks made of Al – 5.5Zn – 1.5Mg – 1Ca – 0.3Mn – 0.2Zr – 0.1Sc alloy have been experimentally confirmed.
The research was carried out at the expense of the grant of the Russian Science Foundation No. 22-19-00121-P. Available at: https://rscf.ru/project/22-19-00121/.

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