Microstructural Analysis of Friction Stir Welding Using CuZn and Zn Fillers on Aluminum 6061-T6: A Comparative Study

Friction stir welding (FSW) is a pivotal solid-state method revolutionizing metal joining diverse manufacturing sectors. This study explored the transformative potential of FSW in welding various metal types, both ferrous and nonferrous, by its ability to create a minimal heat-affected zone (HAZ), thereby mitigating alterations to the microstructure. This research delved into the utilization of filler materials during the FSW process. The investigation centers on scrutinizing the microstructure within the weld nugget area of FSW, employing a 3.1 mm thick aluminum 6061-T6 sheet in a butt joint configuration. Brass and zinc, each 0.2 mm thick, were selected as fillers. Microstructural analyses conducted via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) specifically targeted the weld nugget and HAZ regions. The EDS analysis revealed a higher presence of zinc fillers within the weld nugget than brass, indicating more evenly dispersed grains. SEM observations also highlighted larger grain sizes associated with brass, which could lead to welding defects such as voids and cracks. As such, the study concluded that using zinc fillers manifests a superior microstructure compared to brass during the FSW process involving aluminum 6061-T6.