Microstructure and mechanical properties of friction plug welding for friction stir welded aluminum alloy

Friction plug welding for AA2219-T87 friction stir welds were performed, the macro/micro structures, hardness distributions and tensile strength were observed and tested, and the tensile fracture was observed by scanning electron microscope. The main findings are as follows:With 7500rpm rotational speed and axial force 40~55 kN can obtain defect-free plug welded joint; The ultimate tensile strength (UTS) and elongation of FPW joint in perpendicular direction can reach 336 MPa and 8%, respectively, approximately 73. 9% and 66. 7% being equivalent to that of base metal; The weakest bonding regions are always produced at the bottom bonding interface between the BM and PM and how to control the connection quality of the bottom bonding interface should be the key factor affecting the tensile properties of the friction plug welding joint.