在高功率光纤激光焊接厚度为12 mm的SUS 304不锈钢板的过程中，熔池无法在其自身重力、表面张力、蒸气反冲力等作用力的共同作用下保持动态平衡，熔池内液态金属流动剧烈，使得穿透焊时焊缝表面成型质量较差，容易出现飞溅、表面塌陷以及底部驼峰等焊接缺陷的问题。在确定焊接功率及正面保护种类及气流量等工艺参数的情况下，采用改变单一变量的方法，讨论了焊接速度、离焦量、背面保护气流量以及对接间隙的变化对焊缝表面质量的影响。结果表明：合理的工艺措施可有效改善焊缝质量，优化参数后的焊缝表面光滑、均匀，后续加工量小。拉伸试验表明韧性断裂发生在母材处，而且远离焊缝，最大拉伸应力为809 MPa，对应的应变为64%。

In the process of autogenously welding of SUS 304 stainless steel plate with 12-mm thickness using high power fiber laser, because the welding pool can not maintain homeostasis in the combined action of gravity, surface tension and vapor recoil, the flow of the liquid metal in the molten pool is drastic and the poor formation is easy to cause welding defects of its surface such as spatters, surface undercut and root hump. With certain welding power and top protection gas with certain flow rate, the influences of the welding speeding, defocus, butt joint gap and the flow rate of bottom shielding gas on welding quality by changing the single variable are discussed. The results show that adopting some reasonable technology measures can efficiently improve the welding quality, make the welding surface smooth and well-distributed, and reduce following machining amount after being welded. Tensile test shows that ductile fracture happens in parent metal place, far away from the weld. The maximum tensile stress is 809 MPa, and the mechanical performance of the weld is good.