采用IPG YLS-6000光纤激光器和Slab DC035 CO2激光器，在近似相同的工艺条件下进行平板扫描焊接，通过Olympus光学显微镜测量焊缝横截面积，并计算熔化效率。结果表明：两种激光器焊接的熔化效率均随焊接速度先增加后减小，但是光纤激光焊接熔化效率峰值所对应的焊接速度要远远高于CO2激光焊接。进一步分析表明两种激光焊接熔化效率的差异与激光能量耦合的固有规律不同有关。因此，从焊接效率上考虑，光纤激光器更适合于高速焊接，而CO2激光器更适合于低速焊接。

Bead-on-plate welding is carried out with an IPG YLS-6000 fiber laser and a slab DC035 CO2 laser under the similar conditions. The melting efficiencies are calculated based on the measured weld cross-sectional areas with an Olympus microscope. The results show that the melting efficiency increases firstly and then decreases with welding speed increasing in both cases. However, the welding speed corresponding to the maximum melting efficiency is far greater in fiber laser welding than that in CO2 laser welding. Further analysis demonstrates that the difference of the melting efficiency is relevant to the inherent difference of the energy coupling. Therefore, from the viewpoint of welding efficiency, fiber laser is more suitable for high-speed welding, while CO2 laser is more suitable for low-speed welding.