Microstructure and Properties of 2195-T8 Al-Li Alloy Laser Welded Joint

2195-T8 Al-Li alloy with thickness of 3.7 mm was welded by using high power CO₂ laser welding machine. The effect of welding process parameters on quality of welding joint was investigated, and the microstructure and mechanical properties between as-welded and post-weld solution-aging joints under the optimal welding parameters were compared. The results show that the microhardness of as-welded joint weld seam was 81.81 HV, which had decreased by 32.3% than that of the base metal and the average tensile strength of as-welded joint weld seam was 296 MPa, which had decreased by 49% than that of the base metal. After solution-aging treatment, the microstructure of the weld seam became more homogeneous, and lots of strengthening phases T₁(Al₂CuLi) evenly reprecipitated in the grain boundaries and inside the grains. Meanwhile, the microhardness and the tensile strength had increased by 25.6% and 13.7% than that of weld seam without solution-aging treatment, respectively.