Mechanical, fatigue and microstructural properties of friction stir welded 5083-H111 and 6082-T651 aluminum alloys

In this study, 5083-H111 and 6082-T651 aluminum alloy plates in 6 mm thickness that are used particularly for shipbuilding industry were welded using Friction Stir Welding (FSW) method as similar and dissimilar joints with one side pass at PA position with the parameters of 1250 rpm tool rotation, 64 mm/min welding speed and 2° tool tilt angle. Tensile tests results showed sufficient joint efficiencies and surprisingly high yield stress values. Bending fatigue test results of all joint types showed fatigue strength close to each other. Fatigue strength order of the joints were respectively FSWed 5083-5083, and 6082-6082 similar joints and 5083-6082 dissimilar joint. Cross sections of the weld zones have been analyzed with light optical microscopy (LOM) and fracture surface of fatigue test specimens were examined by scanning electron microscopy (SEM). Although there were no voids in radiographic and microscopic analyzes, 5083-6082 joint showed rarely encountered voiding effect under fatigue load. Microhardness measurements revealed rare result for FSWed AW5083 and novel result for FSWed 6082 aluminum alloy.