Hot forming behaviour of tailor welded aluminium (AA6061-AA8011) alloy sheets using friction stir welding

Tailor Welded Blanks (TWBs) are currently employed in numerous cars because of the advantages of lower vehicle weight. TWBs made of high-strength steel alloys were the subject of the researchers' research between the years 1990 and 2010. The automobile industry's attention switched to the usage of aluminium alloys after 2010, resulting in increased research work on the welding process of aluminium alloys. Aluminum is a lightweight non-ferrous metal that is soft, and its strength is increased by alloying with Mg, Zn, Cu, Mg-Zn & Si metals. Most of these aluminum alloys are used in automobile, aerospace and marine industries. The main objective of this research work is to weld two dissimilar Aluminum alloy sheets AA6061-T6 & AA8011- using Friction Stir Welding (FSW). Optimized Process parameters for FSW i.e., Tool Rotation Speed 1120 RPM, Traverse Speed 50 mm/min, Tilt angle 2 degrees and 1 mm advancing side offset are selected based on the previous experimental data. Stretch forming parameters temperature, strain rate and orientation play a vital role in forming, where temperature has a major effect then strain rate and orientation. Stretching experiments are conducted at temperature 425 degrees C, orientation R60 and strain rates of 0.5 s(-1), 0.05 s(-1),0.005 s(-1), for 6 different widths. The forming performance is investigated by calculating safe, necking and fracture forming limit curves, strain distribution and limiting dome height. The formability of a welded AA6061/AA8011 alloy pair, 2 mm thick, is compared to base materials. In comparison to base metals AA 6061, where n = 0.12 at room temperature, and AA 8011, where n = 0.23 at room temperature, the formability strain limits of TWB are increased by n = 0.32 with elevated forming temperature and decreased strain rate. In addition to the load-displacement behaviour, different weld line orientations related to sheet rolling direction are described, and corresponding forming limit curves are generated.