Volume 57 (2016) Issue 5 Pages 686-690
In this study, the mechanical properties of friction stir lap-jointed A6061/HT590 alloys were evaluated. Friction stir welding was conducted at a tool rotational speed of 500 rpm and a traveling speed of 300 mm/min, where Ar gas was introduced to prevent the materials from corroding during the welding process. Electron back-scattering diffraction was used to characterize the microstructural parameters such as the grain size, misorientation angle, and crystal orientation. The evolution of intermetallic compounds in A6061 during the process was examined in terms of the morphology, size, and aspect ratio in three distinct zones in the Al base material, the heat affected zone, and the stir zone, where transmission electron microscopy was used. It was revealed that friction stir welding gave rise to grain refinement as well as the growth of intermetallic compounds in A6061. The morphological changes in the intermetallic compounds influenced the mechanical properties, resulting in the occurrence of fracture in part of the base material instead of the jointed parts (heat affected zone and stir zone). This study systematically evaluated the microstructural evolution during the friction stir welding for joining A6061 with HT590 and its effect on the mechanical properties.