Microstructural Characterization and Mechanical Properties of Refill Friction Stir Spot Welded Aluminum Alloy AA6181-Ti6Al4V Dissimilar Joint

摘要

Due to their properties, demand of multi-materials structures made of titanium and aluminum has increased to reduce weight and cost (Al alloys), and improve strength and corrosion resistance (Ti alloys). However, joining Al alloys to Ti alloys is challenging due to their chemical incompatibility and also different physical characteristics. Therefore, it is an emergent problem to be solved for future industrial application. In the present study, refill friction stir spot welding or also known as friction spot welding of dissimilar AA6181 Al alloy to Ti-6Al-4V was studied. Sound joints with maximum lap shear strength of 6.4 kN were achieved. It was noticed that rotational speed significantly influences the mechanical performance of the joints. Microstructure analyses and local properties characterization by nanoindentation reveal that medium tool rotational speed produces thin and strong layer of Ti(Al,Si)3 intermetallic at the interface.