An investigation on Friction Spot Welding in AA6181-T4 Alloy


Friction spot welding is a new solid state welding process, invented and patented by the GKSS Research Centre GmbH in Germany, suitable for spot joining lightweight low melting point materials such as Al and Mg alloys. The process is performed with an especially designed rotating tool (comprised by a clamping ring, sleeve, and pin) that creates a joint between sheets in overlap configuration by means of frictional heat and mechanical work. The result is a spot welded lap joint with minimal material loss and a flat surface with no keyhole. In this work the application of Friction Spot Welding for spot joining the AA6181-T4 is investigated. Different rotational speeds (1900 to 2900 rpm) and welding times (2 to 3.4 s) were tested with the objective of finding the best suited ones for producing high quality joints in terms of microstructure and mechanical performance. Welds with strength in the order of 6.8 kN were obtained with high reproducibility. The results also show that geometric elements of the weld play an important role on the fracture mechanisms and hence on the mechanical performance of the joints. In sum, the results reveal the potential of this process for industrial applications.
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