工艺参量对NdFeB永磁体和SPCC钢激光点焊质量的影响

为了将激光点焊工艺应用于NdFeB永磁体与冷轧碳钢薄板的连接,试验研究了脉冲功率、脉冲宽度和离焦量对焊点形貌和接头强度的影响。激光点焊中存在热导焊和深熔焊两种焊接模式,改变峰值功率和离焦量都能使焊接模式发生转变,而改变脉宽时焊接模式不转变。点焊试样剪切试验中存在脱壳式、剪断式和压断式3种断裂模式,所对应的熔核尺寸和剪切载荷依次增加。结果表明,为获得较高的连接强度,宜使峰值功率与离焦量适当配合,实现深熔焊模式进行焊接,而脉冲宽度不宜太大。

Effects of process parameters in laser spot welding of NdFeB permanent magnets and SPCC steels

On the demands of high speed and micromation, the welding of NdFeB permanent magnet material has been paid increasing attention nowadays. Previous studies have shown that the joining of dissimilar magnet and steel materials can be realized by laser spot welding, but it is still not clear how the welding parameters affect the weld quality. In this paper, the influences of laser pulse power, pulse duration, and defocusing distance on weld features and strength in laser spot welding of NdFeB and SPCC are studied experimentally. The results show that there are both conduction welding and keyhole welding in the laser spot welding under our experimental conditions. Welding modes can be transformed by changing peak power or defocusing distance, but not altered by changing pulse duration. There are three fracture modes in shearing tests, i.e., exuviation, shear and crush fractures, with nugget dimensions and shearing loads increasing in turn. To gain good joint strength, the pulse peak power and defocusing distance should be chosen appropriately to implement welding in keyhole mode, and moreover, pulse duration should not be too long. The above findings can be used as guideline in the selection of process parameters for laser spot welding of NdFeB permanent magnet, and are the foundation for industrial applications of laser spot welding process in joining dissimilar magnet and steel materials.