Influence of Welding Speed on Microstructure and Mechanical Properties in Friction Stir Additive Manufacturing of Aluminum Alloys

This study investigates the effect of welding speed on the microstructure and mechanical properties of aluminium alloys in Friction Stir Additive Manufacturing (FSAM), with a fixed rotational speed of 900 RPM. Welding speeds of 20 mm/min, 40 mm/min, and 60 mm/min were employed to evaluate their impact on tensile strength, microstructure, and overall material performance. The results show a complex relationship between welding speed and tensile strength. At a welding speed of 20 mm/min, the tensile strength was observed to be 99 MPa, while at 40 mm/min, it increased to 174 MPa. However, further increase in welding speed to 60 mm/min led to a slight decrease in tensile strength to 96.72 MPa, before returning to 100.56 MPa at the highest welding speed, suggesting a non-linear behavior. Microstructural analysis revealed that slower welding speeds resulted in a finer grain structure due to lower cooling rates, whereas higher welding speeds led to slightly coarser grains but enhanced material homogeneity. These findings indicate that optimal welding speed is crucial for maximizing tensile strength and achieving desirable mechanical properties. The study highlights the importance of precise control over welding parameters for the production of high-performance aluminium components in FSAM, with potential applications in industries such as aerospace and automotive.