基于0.5 mm厚Hastelloy C-276薄板进行了脉冲激光填丝焊接实验，研究了激光单脉冲能量和离焦量对焊缝成形的影响规律。研究结果表明，单脉冲能量和离焦量主要影响脉冲激光焊接热输入量、光斑大小和激光空间分布，并且对焊缝成形的宏观形貌影响较大；随着热输入量的增大，焊缝上下熔宽增大，焊缝下余高和下接触角也增大；在一定离焦量范围内，激光光斑直径越大，焊缝熔宽越大；受激光空间分布的影响，负离焦时，焊缝上熔宽总是略大于下熔宽；在一定工艺条件下，可获得正余高可控的焊接接头及熔宽、余高和接触角均匀而熔宽较小的焊缝形貌；焊缝上下表面光滑、均匀，表现出半圆波浪条纹特征。

The experiment of pulsed laser welding with filler wire on 0.5 mm thick Hastelloy C-276 sheets is conducted, and the influence rules of laser single pulse energy and defocusing on the weld joint forming are studied. The study results show that the single pulse energy and the defocusing mainly influence the heat input of pulsed laser welding, spot size and spatial distribution of laser beam, and they also have a great influence on the macroscopic morphology of the weld joint forming. With the increase of the heat input, both of the top and bottom welding widths of weld joints increase, and the bottom reinforcement and the bottom contact angle of weld joints also increase. In a certain range of defocusing, the larger the laser spot diameter is, the wider the weld joint width is. With the influence of the laser beam spatial distribution, the top welding width is always slightly larger than the bottom welding width when the defocusing is negative. Under a certain process condition, the weld joints with controllable positive reinforcement, and the weld joint appearance with uniform weld width, reinforcement and contact angle, but small weld width, can be obtained. The top and bottom surfaces of weld joints are smooth and uniform, which show a feature of semicircular wave stripes.