Comparison of mechanical and microstructural properties of single and double sided friction stir welded aluminum alloy joints

In this study, AA 5083-H111 and AA 6082-T651 aluminum alloy sheets were joined by friction stir welding (FSW) and double-sided friction stir welding (DS-FSW) methods at different rotation speed and traverse speed. Tensile tests, bending tests, microhardness measurements, and metallographic examinations were performed on the sheets joined at different parameters and the findings were compared. In some of the studied parameters, tool-induced deformations were clearly observed on the surfaces of the joints and it was concluded that this reduced the strength of the joints. The tensile strength of the FSW joints ranged between 208,17-239,55 MPa. The tensile strength of the DS-FSW joints ranged between 194,11-204,91 MPa.The bending test results showed that damage occurred on the weld surface and weld root in FSW joints, but no damage occurred in the DS-FSW joints. Light microscope examinations showed, onion ring shaped shear bands were clearly seen in the weld center of welded joints. In welded joints, hardness values were low on the AA 5083 side, while they tended to increase towards the AA 6082 side. Keywords: Friction stir welding (FSW), double-sided friction stir welding (DS-FSW), Al alloy