Effect of Intermetallic Compounds Formation in Solid State Welded Dissimilar Materials
In this study, the mechanical properties of friction stir lap-jointed Al6061/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 Al6061 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 Al6061. 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
Al6061 with HT590 and its effect on the mechanical properties.
Keywords: Al6061, HT590, Microstructures, Mechanical Properties, Intermetallic Compounds.