采用连续Nd:YAG激光对Fe-Ni(质量分数为36%)合金进行单道扫描实验。借助金相显微镜观察焊缝截面形貌的几何特征。分析工艺参数(激光功率、扫描速度、离焦量、焊接角度以及热输入量)变化对焊缝截面几何特征的影响。结果表明：较大的负离焦量将导致大负余高的出现，减薄材料，不利于激光自熔焊；在离焦量不变的情况下，激光功率的提高较之减小扫描速度更有助于增大熔深；在使用热输入量(功率/扫描速度)作为复合表征量分析焊缝形貌时，应考虑上述激光功率与扫描速度之间的关系带来的影响。

Continuous wave (CW) Nd:YAG laser beam bead-on-plate welding of Fe-Ni (36%, mass fraction) alloy is carried out. The morphology of the cross section is analyzed by optical microscope. The influence of welding parameters (laser power, scanning speed, defocusing amount, welding angle and heat input) on the morphology of the cross section is studied. The results indicate that large negative focusing position will weaken the weldments, consequently, is of disadvantage to self-fusible welding. And the increase of laser power is more helpful to improve welding penetration than slowing down welding speed when the focusing position is fixed. The influence of the relationship between laser power and welding speed should be considered when heat input (laser power/welding speed) is used to characterize the morphology of the weld.