The material used in this work was SSM 6061 Al alloy which obtained from SSM squeeze casting technique. The
chemical composition of SSM 6061 is listed in Table 1. The friction stir welding plates were 100 mm in length, 50
mm in width and 4 mm in thickness. The cylindrical pin was used for friction stir welding. The diameter of the
shoulder was 20 mm. The diameter and length of the pin were 5 mm and 3.8 mm, respectively. The welding tool
was rotated in the clockwise direction and specimens, which were tightly fixed at the backing plate, were traveled,
In this work, the welding speeds was at 160 mm/min. The tool rotation speeds were at 710, 1000 and 1400 rpm, the
tilt angle was 3