In this paper, fibre laser-cold metal transfer arc (CMT) and oscillating fibre laser-CMT hybrid welding processes were adopted for A7204P-T4 aluminium alloy sheets with thickness of 6 mm. Furthermore, the effect of Nb content on microstructure and mechanical properties, the metallurgical behaviour, and influence mechanism were investigated. Oscillating laser effectively reduced the weld porosity and increased the joint’s elongation after fracture by 81%. With the addition of Nb, the heterogeneous nucleation significantly refined weld grains and removed columnar and dendritic structures which attributed to the solute segregation of Nb and primary phase NbAl_3. The average tensile strength of joints with 0.43%, 0.74%, and 0.83% Nb mass fractions to 336, 334.5, and 341 MPa, respectively.

本文对厚度为6mm的A7204P-T4铝合金薄板采用了纤维激光冷金属转移电弧（CMT）和振动纤维激光-CMT混合焊接工艺。此外，研究了铌含量对组织和力学性能，冶金行为以及影响机理的影响。振荡激光有效地降低了焊接孔隙率，并使接头断裂后的伸长率提高了81％。随着Nb的添加，异质形核显着细化了焊缝晶粒，并去除了柱状和树枝状结构，这归因于Nb和主相NbAl ₃的溶质偏析。接头的平均抗拉强度为0.43％，0.74％和0.83％Nb质量分数分别为336、334.5和341 MPa。