采用高功率光纤激光对3mm厚铝合金进行焊接实验,系统研究了离焦量对焊缝熔池形貌、熔深、熔宽、底部驼峰及深宽比、宽度比例系数的影响。结果表明,随着离焦量的增加,焊接模式由深熔焊转变为热导焊,熔宽变化不明显,底部驼峰高度和宽度比例系数降低;用高功率光纤激光焊接时,通过减小负离焦量或改变为正离焦的方式能降低焊缝塌陷程度与底部驼峰高度;用较低功率光纤激光焊接时,通过增大负离焦量或减小正离焦量的方式能增大背面熔宽。 High-power fiber laser was used to weld 3mm thick aluminum alloy. The effects of defocusing amount on weld pool morphology, penetration depth, weld width, bottom hump and aspect ratio and width ratio coefficient were systematically studied. The results show that as the amount of defocus increases, the welding mode changes from deep fusion welding to thermal conduction welding, the melting width does not change obviously, and the ratio coefficient of the bottom hump height and width decreases. When using high power fiber laser welding, The amount of defocus or change to positive defocusing can reduce the degree of weld collapse and bottom hump height; with lower power fiber laser welding, the amount of negative defocus can be increased or the amount of positive defocus can be increased Back melt width.