Friction Stir Welding Between Sheets and Extruded Profiles

In the Friction Stir Welding process (FSW), usually two sheets are joined by means of a rotating pin. Nevertheless, some industrial applications of this process require the joining of three bodies such as in the naval and aeronautical applications, where the two sheets has to be joined with a third body in order to realize a structural component. These types of joint are usually called T-joint or corner welds, and are usually realized by joining three sheets. In this paper, a novel approach is presented for joining two AA6082 sheets with aluminum extruded profiles made by AA6082 and AA6060. The advantages of this approach are numerous: profiles can be directly extruded with the desired shape, while rolled sheets have to be bended in order to get the desired geometry and the mechanical proprieties of the extruded profiles are comparable to the rolled sheets ones; moreover, an extruded profile can assume almost every kind of shape, thus allowing an optimized oriented design of the structural component. As a last remark, aluminum extruded products have almost the same price of rolled ones when big lots are required. In this work, the FSW process for joining two sheets and an H-shape extruded profile is presented and discussed. In the experiments, several PIN shapes and process parameters are investigated in order to produce a sound weld. The process conditions and PIN shapes are reported and the results of mechanical and metallurgical characterization of the joint are presented. Several specimens were extracted from the different experimental conditions, and then tensile tested, while optical microscope analysis and micro hardness measurements were performed in the cross section in order to investigate the material flow and the presence of defects.