Optimization of Mechanical Properties and Microstructure of Friction Stir Welded AA6061-T6 Joints Using Response Surface Methodology
Authors: A. Kumar, R. Singh, S. Sharma
Friction stir welding (FSW) is a solid-state joining process widely used for aluminum alloys. This study investigates the effect of process parameters—tool rotational speed, welding speed, and tool tilt angle—on the mechanical properties and microstructure of AA6061-T6 alloy joints. Response surface methodology (RSM) was employed to design experiments and develop predictive models for tensile strength, hardness, and elongation. The results indicate that rotational speed and welding speed significantly influence the joint properties, while tool tilt angle has a lesser effect. Microstructural analysis revealed that the nugget zone exhibits fine equiaxed grains due to dynamic recrystallization, leading to improved mechanical properties. The optimal parameter combination was found to be 1200 rpm, 80 mm/min, and 2° tilt angle, resulting in a maximum tensile strength of 310 MPa, which is 85% of the base metal strength. The developed models show high accuracy with R² values above 0.95, confirming their reliability for predicting joint properties. This work provides valuable insights for optimizing FSW parameters to achieve high-quality welds in aerospace and automotive applications.
