在细管径侧吹气体的辅助下,对SUS 304不锈钢试样进行了光纤激光焊接，使用高速摄影设备配合背景激光光源对匙孔、熔池以及金属蒸气的行为进行了观察，并对焊缝熔深和焊缝成形进行了分析。结果表明：在激光功率、焊接速度、离焦量、喷嘴位置与角度等参数一定的情况下，焊缝熔深随着细管径侧吹气体流量的增大而增加。细管径侧吹气体可以明显打开匙孔并维持匙孔稳定性，并扩大熔池面积。气体流量大小对焊缝成形有较大影响。当无细管径侧吹气体时，飞溅较大，焊缝成形均匀；当气体流量较小时，飞溅较小，且焊缝成形均匀；当气流量过大时，飞溅较小，但焊缝成形较差。

With the assistance of the small diameter side-blown gas, the fiber laser welding of SUS 304 stainless steel sample is performed. The behaviors of keyholes, molten pools and metallic vapor are observed by using the high-speed photography equipment under the background light source and the fusion depth and formation of welds are also analyzed. The results indicate that, when the laser power, welding speed, defocusing amount, position and angle of gas jet nozzle, and other welding parameters are constant, the fusion depth of welds increases with the increment of small diameter side-blown gas flow. The small diameter side-blown gas can open the keyholes obviously, maintain the stability of the keyholes, and also enlarge the area of the molten pool. The gas flow value has a great influence on the formation of welds. Without the small diameter side-blown gas, the uniformly-distributed weld formation with lots of the spatters is achieved. When the gas flow value is small, the uniformly-distributed weld formation with few spatters is achieved. When the gas flow value is too large, the spatters are few and the weld formation is poor.