The 2 mm thick 2060-T8/2099-T83 Al-Li alloy T-joints were welded by dual laser-beam bilateral synchronous welding (DLBSW) with ER4047 filler wire. The metallurgical porosity defects under different welding parameters were investigated to study the influence of laser power and weld speed on the porosity distribution, formation mechanism and mechanical properties during DLBSW process. In order to explore the special effect of welding heat input on the difference of alloying elements content around porosity, a comparative analysis of elements content between the porosity boundary and matrix around porosity was studied. It was found that the weld porosity defects were increased significantly as the laser power increased. Besides, the heat affected zone (HAZ) and branches of dendritic crystals were the key positions of porosity nucleation and formation. The results of tensile test and SEM of failure surface demonstrated that porosity was one of the important factors leading to weld bead failure. In particular, the porosity in the bottom fusion zone and EQZ significantly weakened the performance of the T-joint.

2mm厚的2060-T8 / 2099-T83 Al-Li合金T型接头通过采用ER4047填充焊丝的双激光束双向同步焊接（DLBSW）进行焊接。研究了不同焊接参数下的冶金孔隙率缺陷，研究了激光功率和焊接速度对DLBSW过程中孔隙率分布，形成机理和力学性能的影响。为了探讨焊接热量输入对孔隙度周围合金元素含量差异的特殊影响，对孔隙度边界与孔隙周围基质之间的元素含量进行了比较分析。已经发现，随着激光功率的增加，焊缝孔隙率的缺陷显着增加。此外，热影响区（HAZ）和树枝状晶体的分支是孔隙成核和形成的关键位置。 的 失败 表面表明，孔隙率为的导致焊道失败的重要因素之一。尤其是，底部熔合区和EQZ的孔隙度显着削弱了T型接头的性能。