JSC Samara Metallurgical Plant (Samara, Russia)

А. М. Drits, Director of Business and Technology Development, Candidate of Technical Sciencees, Associate Professor, dritsam@gmail.com

Moscow Polytechnic University (Moscow, Russia)
V. V. Оvchinnikov, Head of the Department of Materials Science2, Doctor of Technical Sciences, Professor, vikov1956@mail.ru
P. S. Dmitrashko, Postgraduate Student of the Department of Materials Science, garentor@mail.ru
D. М. Bogush, Postgraduate Student of the Department of Materials Science, den.bogush@mail.ru

The paper presents the results of a study on the friction stir spot welding (FSSW) of lap joints made from 1 mm thick AA6022 aluminum alloy sheets. It was established that the joint strength is primarily governed by the key welding parameters, namely tool rotational speed, axial force, and welding time. Welding trials were carried out at tool rotational speeds of 600, 800, 1000, 1800, 2500, and 4000 rpm. For selected specimens, the heat input during welding was measured and the thermal cycle was recorded. Macrostructural analysis showed that defectfree spot welds were formed over a wide range of tool rotational speeds, from 800 to 2500 rpm. With a welding time of 3s, the optimal process parameters were found to be a tool rotational speed of 1000–1800 rpm and an axial force of 4500–5000 N. Under these conditions, the friction stir spot welding process produced joints with tensile pull-out loads of 0.92–0.98 kN and lap shear loads of 2.46–2.58 kN. Grain refinement within the stir zone was observed under all investigated welding conditions. Removing mechanical contamination from the faying surfaces prior to welding did not result in a significant increase in either the lap shear or pull-out strength of the joints. Post-weld artificial aging increased both the lap shear and pull-out strengths of the welds by an average of 25–30%.
This research was supported by the V. E. Fortov Grant of Moscow Polytechnic University.
The study was carried out using the equipment of the Shared Research Center “High Technologies in Mechanical Engineering” of Moscow Polytechnic University.

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