Properties and structure investigation of the friction stir welding seam of the AA6061-T6 plates

Friction stir welding (FSW) is a relatively new welding technique that has significant advantages compared to the fusion welding techniques in joining non weld able alloys by fusion, such as aluminum alloys. Three FSW seams of AA6061-T6 plates were made using different FSW parameters. The structure of the FSW seams was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and non destructive testing (NDT) techniques and their hardness was also measured. The dominate phase in the AA6061-T6 alloy and the FSW seams was the α-Al. The FSW seam has lower content of the secondary phases than the AA6061-T6 alloy. The hardness of the FSW seams was decreased by about 30% compared to the AA6061-T6 alloy. The temperature distributions in the weld seams were also studied experimentally and numerically modeled and the results were in a good agreement.