The Influence of Tool Geometry for Refill Friction Stir Spot Welding (RFSSW) on Weld Properties During Joining Thin Sheets of Aluminum Alloys

The paper presents the results of research on the modification of the face geometry of the refill friction stir spot welding tool sleeve for welding thin aluminum sheets with an Alclad and an oxide anode coating. The analysis of the impact of such modification on the process perform (tool motion parameters, temperature) and microstructure as well as mechanical strength of the lap joints were analyzed. The tests were carried out using aluminum alloy 2024-T3 sheets with thickness 1.27 mm. For comparative purposes,joints were also made using plates without an Alclad and without anodized coating with using unmodified tool and modified toolswith developed 3 variants of face geometry. The samples with the joint were subjected to metallographic and strength tests. It has been shown that the use of modified geometry has a decisive influence on the performance of the process and the effect of softening and mixing of materials in the zone of point connection.