Process, microstructures and mechanical properties of double-sided fiber laser beam welded T-joints of aluminum-lithium alloys 2060 and 2099

Alcoa’s third-generation aluminum-lithium alloys 2060-T8 and 2099-T83 were joined together to form T-joints by double-sided fiber laser beam welding using aluminum-silicon alloy 4047 filler wire. The influence of the incident beam angle, the incident beam position, the beam separation distance and the welding heat input were investigated regarding to weld microstructural features. It was observed that a good fusion between the two parts of T-joints could be obtained by using smaller incident beam angle. The forming requirements of the weld seam were met when the incident beam position was 0.1mm yielding a 45∼50° weld seam angle. To ensure weld microstructure consistency and improve the T-joints’ mechanical properties, beam separation distance must be strictly controlled to achieve the fusion of the double-sided welds in a common molten. High speed welding was a favorable process for reducing the weld penetration and avoiding the porosity of the weld. For welds with a fully fusion and uniform microstructure, the key factor restricting the long transverse (LT) tensile strength was weld penetration.