采用CO2激光器对高强铝合金2519-T87进行焊接,研究了其激光焊接头组织和力学性能特征,并与熔化极气体保护焊(MIG)焊接头的组织和力学性能进行了对比。实验结果表明,激光焊焊缝组织细小,晶界共晶相呈短棒状均匀分布,时效后焊缝中有大量细小θ′相均匀析出,且熔合线附近没有形成等轴晶区,而熔化极气体保护焊焊缝组织晶粒粗大,晶界共晶相呈长条网络状分布,时效后焊缝中的θ′相尺寸大,数量少,且分布不均匀,熔合线附近还存在一个较宽的等轴晶区。焊后时效激光焊接头抗拉强度可达到母材的74%,并且随着焊接速度的增加,接头抗拉强度随之增加,而熔化极气体保护焊焊接头抗拉强度仅仅只有母材的61%,且激光焊接头的热影响区(HAZ)中没有明显的软化区。

CO2 laser beam was used to weld 2519-T87 high strength aluminum alloy, and the microstructure and mechanical properties of the welds were studied and compared with the melting electrode inert gas (MIG) welds. Results indicate that the grains in laser welds are very fine, and the eutectic phase distributes more uniformly. After aging treatment, there are lots of finer θ′ phase in laser welds. And there is no equiaxed grain zone along the laser weld fusion line. Whereas the grains in MIG welds are coarser. The eutectic phase is strip morphology and network distributes along the grain boundary. After aging treatment, the size of θ′ phase is big and number of θ′ phase is small, and it does not distribute uniformly in the grains. There is a wide equaixed grain zone along the fusion line. The tensile strength of the laser weld after aging treatment can reach 74% of that of the base metal, whereas the tensile strength of MIG weld is only 61% of that of the base metal. And there is no softened zone in the heat affected zone (HAZ) of laser welds.