Comparison of mechanical properties of AA6061-T6, AA7075-T6 material pairs combined with friction stir welding

Aluminum alloy materials have become indispensable materials for the aviation and space industry due to their lightness and superior strength. However, the generally low welding capabilities necessitate the use of rivets in joining these materials. Although rivets are highly durable elements in terms of strength, the negative effects of rivet and riveting process on some very important mechanical properties such as fatigue strength cannot be neglected. However, the effects of rivets on the structural weights of the products manufactured in the aviation and space industry, where rivets are frequently used, reach levels that cannot be neglected considering the number of rivets used. FSW (Friction Stir Welding), a newly developed welding method, is a very suitable method especially for materials with low melting temperature such as aluminum alloy materials. One of the most important advantages of this method is that it can successfully weld two materials of different types and does not cause large amounts of thermal stress as in other welding methods. Within the scope of this study, the effects of the test parameters on the welding quality were investigated in the friction stirring welding method of friction stirring welding method of AA6061-T6 and AA7075-T6 aluminum alloy plates of 100 mm × 125 mm dimensions, each of which has a thickness of 2 mm. As three different control variables, each of which consists of three levels, tool rotation speed 500rpm, 710rpm and 1000rpm, tool feed rate 20 mm / min, 28 mm / min and 40 mm / min and tool tilt angle 0°, 0.5° and 1° were selected and the effect levels of these control factors were compared for 3 different combinations as AA6061-AA6061, AA7075-AA7075 and AA6061-AA7075. 135 pairs of plates, which were joined in accordance with the test plan made in 3 repetitions by using the response surface method, were subjected to tensile test to determine their tensile strength after being cut with water jet. As a result of the analysis made in Minitab19 using the values obtained from the tensile tests, the effect coefficients of the control factors were calculated and the optimum process parameters were determined.