Forced Cooling Friction Stir Welding of 2060-T8 Al-Li Alloy

Friction stir welding of 2060-T8 Al-Li alloy was experimentally investigated. Forced cooling process was realized by placing two copper pressure plates with a waterway on both sides of weld top surface. The relations between joint formation, microstructures and mechanical properties were mainly discussed. Compared with conventional joint by natural cooling, the welding joint with smaller flashes by forced cooling has the smaller well-distributed grains and higher microhardness in the stir zone (SZ). The tensile strength and elongation of forced cooling joint, respectively, reach 445.7 MPa and 6.7%, which are obviously higher than those of the conventional joint. The fracture locations of the conventional and forced cooling joints are located in the SZ, and the fracture surface morphologies show a typical ductile fracture mode.