Effect of heat treatment on tensile properties of friction stir welded joints of 2219-T6 aluminium alloy

The effect of post-weld heat treatment (PWHT) on the tensile properties of friction stir welded (FSW) joints of 2219-T6 aluminium alloy was investigated. The PWHT was carried out at aging temperature of 165 degrees C for 18 h. The mechanical properties of the joints were evaluated using tensile tests. The experimental results indicate that the PWHT significantly influences the tensile properties of the FSW joints. After the heat treatment, the tensile strength of the joints increases and the elongation at fracture of the joints decreases. The maximum tensile strength of the joints is equivalent to 89% of that of the base material. The fracture location characteristics of the heat treated joints are similar to those of the as welded joints. The defect free joints fracture in the heat affected zone on the retreating side and the joints with a void defect fracture in the weld zone on the advancing side. All of the experimental results can be explained by the hardness profiles and welding defects in the joints.