Abstract: Laser welding with powder filling is a highly flexible welding technology due to its effective reduction of the assembly accuracy of workpiece. Based on the correlation between the density of powder distribution and the image gray, the distribution density on the cross section of the powder beam is measured, and the effectiveness of the powder delivery with a self-developed lateral device for powder feeding is analyzed. Furthermore, the welding technological properties and the joint performance in fiber laser welding of high strength galvanized steel with powder filling are studied. The results show that：The powder position is the key factor of the rate of the powder utilization. When filling powder laterally in angle of 45°, the most effective delivery rate can be obtained with the powder position of –1.75 mm. The power would to be fed into the welding pool ineffectively when powder position is too close to or far away from the laser beam. The highest rate of the powder utilization can be realized with the powder position of –4 mm. The copper content on the weld center section decreases linearly with the reduction of the powder feeding speed. Powder filling can significantly improve the performance of the weld surface and refine the grains in the heat-affected zone, as well as the improvement of the weld properties. Laser welding with powder injection is able to improve the weld surface quality, create finer microstructure in the heat affected zone, improve the strength of the weld, as well as increase the gap tolerance and reduce the assemble accuracy of the workpiece.

Key words: laser welding;powder delivery;powder filling;assembly accuracy