Experimental Correlation Between Microstructure, Residual Stresses and Mechanical Properties of Friction Stir Welded 2024-T6 Aluminum Alloys

Friction stir welding was performed on AA2024- T6 aluminum plates using different rotation and traverse speeds with the objective of improving the mechanical strength and microstructure properties. The influence of the traverse and rotation speed on the microstructures, mechanical properties and residual stresses of the welded Aluminum plates were investigated. By increasing the rotation speed, stirred zone grain size became larger. Besides, the homogenous second phase distribution was obtained. Furthermore, by increasing both rotational and traverse speeds, hardness of the thermo-mechanically affected zone and the stirred zone increase to base metal hardness. These welded plates that were fractured at advancing side have a maximum tensile strength equal to 71% of base plate strength which was obtained at 31.5 mm/min traverse speeds and 1120 rpm rotational speed. The longitudinal residual stress was diminished with decreasing of rotational speed by 1120 rpm at a constant traverse speed. In this conditions and by increasing the traverse speed by 31.5 mm/min, the maximum tensile strength was obtained as many as 48%. It was attributed to more plastic deformation and minimum grain size in the weld zone due to higher traverse speed.