Influence of Joint Geometry on Micro and Macro Mechanical Properties of Friction Stir Spot Welded Joints

Spot welding can be considered a very common joining technique in automotive and transportation industries as it permits to obtain effective lap-joints with short process times and what is more it is easily developed through robots and automated systems. Recently, Friction Stir Spot Welding (FSSW) has been proposed as a natural evolution of the already known Friction Stir Welding (FSW) process, allowing to obtain sound spot joints that do not suffer from the insurgence of typical welding defects due to the melting of the base material. Similarly to FSW, both geometrical and technological parameters must be considered as they affect the material flow and the heat flux generated during the process. In the paper the results of an experimental campaign on AA6082-T6 aluminum alloy are presented. Lap joints have been FSSWed under different process conditions. During the process temperature fields have been measured through embedded thermocouples. The micro and macro mechanical joint properties have been measured and the effect of the joint geometry on the microstructure and local strength of the material was highlighted.