Comparative investigation of tungsten inert gas and friction stir welding characteristics of Al-Mg-Sc alloy plates

Al-Mg-Sc alloy plates were welded by FSW and TIG welding. The effect of welding processes on mechanical properties of Al-Mg-Sc welded joints was analyzed based on optical microscopy, transmission electron microscopy, tensile testing and Vickers microhardness measurements. The results show that the mechanical properties of FSW welded joint are much better than those of TIG welded joint; the strength coefficient of FSW joint is up to 94%. Moreover, tensile strength and yield strength of FSW joint are 19% and 31% higher than those of TIG joint, respectively, which are attributed to the preservation of cold working microstructures in the process of FSW. Due to the low welding temperature during FSW process and the excellent thermal stability of Al3(Sc, Zr) particles, the cold working microstructures can be well preserved. In addition, the FSW joint have asymmetric microstructures and mechanical properties, which are not observed in TIG welded joint.