Optimization of Mechanical Properties and Microstructure of Friction Stir Welded AA6061-T6 Joints Using Response Surface Methodology

• Optimal FSW parameters (1200 rpm, 80 mm/min, 2° tilt) yield tensile strength of 310 MPa, 85% of base metal. • Rotational speed and welding speed are the most influential parameters on joint mechanical properties. • Fine equiaxed grains in the nugget zone due to dynamic recrystallization enhance mechanical performance. • RSM models with R² > 0.95 accurately predict tensile strength, hardness, and elongation.