Arconik SMZ JSC, Moscow, Russia:

A. M. Drits, Director for Business and New Technology Development, Candidate of Technical Sciences, e-mail: Alexander.Drits@arconic.com

Moscow Polytechnic University, Moscow, Russia:
V. V. Ovchinnikov, Professor at the Department of Metal Science, Doctor of Technical Sciences, e-mail: vikov1956@mail.ru

The report presents the results of mechanical tests of welded joints of cast aluminum alloys: AM4,5Kd, AM5, VAL16 produced by manual multi-pass argon-arc welding with additive wire Sv1201 and SvAMg63 and by double pass friction stir welding. During friction stir welding (FSW) tool rotation causes heating and plasticizing of metal. Moving the tool along the seam leads to metal transfer to the area released behind the tool. As a result, stirring of welded metal occurs with the formation of welded joint. The processes of intense plastic deformation affect the formation of the microstructure of the welded joint, on which its strength properties depend, and the time — temperature parameters at which the friction stir welding process is realized are a determining factor. The study of the structure of the core of welded seam found the special layered structure of metal, which consists of recrystallized grains separated by high-angle boundaries. Independence of this structure from the initial state of welding billets demonstrates the self-organization of micro-structure of core zone for which formation temperature and plastic deformation are determining factors. It is found that during FSW of cast aluminum alloys fully recrystallized structure with the same medium-sized grains (3.9–5.3 mkm) is formed in the core of welded seam. The level of mechanical properties of welded joints made by friction stir welding (FSW) for these alloys significantly exceeds the level of mechanical properties of joints produced by multi-pass argon-arc welding. The strength coefficient of welded joints of alloys AM4.5Kd, AM5 and VAL16, made by friction stir welding, is 79.2, 81.3 and 96.7%, respectively.

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