为了研究磁场对激光焊接的影响, 采用在工件旁放置永磁铁、提供横向或者纵向常磁场对不锈钢进行激光电流热丝焊接的方法, 结合焊缝横截面形状以及焊缝组织等, 对不同磁场下激光热丝焊接头进行了分析。结果表明, 磁场的加入对焊接过程和接头形状有显著影响, 适当的磁感应强度能稳定激光热丝焊接过程, 磁感应强度过大则易造成大量飞溅; 焊缝接头的形状随磁场的方向、极性以及磁感应强度的变化而改变; 横向磁场的加入能提高激光热丝焊接效率; 磁场还能减少焊缝柱状树枝晶区域, 促进胞状晶的形成, 提高焊缝的显微硬度值。外加磁场在焊接熔池中产生了安培力, 安培力是搅拌熔池的主要作用力, 从而改变液态金属流动, 造成激光热丝焊接头形状和组织的改变。

In order to study the influence of magnetic field on laser welding, the longitudinal or transverse magnetic field was employed via adding a permanent magnet next to the specimen. Experiment investigation on laser hot wire welding of stainless steel was performed with additional magnetic field. By combining the weld cross section shape and weld microstructure, laser hot wire welding joints under different magnetic fields were analyzed. The results show that, the addition of magnetic field has a significant effect on the welding process and joint shape. The appropriate magnetic induction intensity can stabilize the laser hot wire welding process. But too large magnetic induction intensity would cause a large number of splashes. The shape of welding joint changes with the change of the direction of magnetic field, the polarity of magnetic field, and magnetic induction intensity. Transverse magnetic field can improve the welding efficiency of laser wire. Magnetic field can also decrease the columnar dendrite area, promote the formation of cell crystal, and increase the micro hardness value of weld. The additional magnetic field causes the generation of ampere force in the welding pool. Ampere force is the main force to stir pool. It changes the flow of molten metal and causes the changes of head shape and microstructure of laser hot wire welding.