采用Nd:YAG脉冲激光焊机实现了200μm厚的NiTiNb形状记忆合金的激光焊接。焊接接头在850℃进行了退火处理。借助于光学显微镜、扫描电镜、精密拉伸机对接头的显微组织和力学性能进行了分析。结果表明,未热处理焊接接头的显微组织存在分层现象。熔合区的晶粒外延生长,焊缝中心为细小的等轴晶。焊接接头的抗拉强度为母材的90%。焊接接头断口韧窝小而浅,表现为延性断裂。热处理后焊缝的等轴晶消失,粗晶区和偏析区交替分布。母材和焊接接头都出现了应力诱发马氏体现象,表现为伪弹性。焊接接头的屈服强度仅为母材屈服强度的60%,母材和焊接接头的显微硬度低于热处理前的显微硬度。 The laser welding of NiTiNb shape memory alloy with 200μm thickness was realized by Nd: YAG pulsed laser welding machine. Welded joints were annealed at 850 ° C. The microstructure and mechanical properties of the joint were analyzed by means of optical microscope, scanning electron microscope and precision stretching machine. The results show that there is delamination in the microstructure of the welded joint without heat treatment. The grain boundaries of the fusion zone grow epitaxially and the center of the weld is a fine equiaxed grain. The tensile strength of the welded joint is 90% of the base metal. Fracture dimples welded joints small and shallow, showing ductile fracture. The equiaxed grains of the weld disappeared after heat treatment, and the coarse grains and segregation areas were alternately distributed. The base metal and welded joints have appeared stress-induced martensite phenomenon, the performance of pseudo-elastic. The yield strength of the welded joint is only 60% of the yield strength of the base metal, and the microhardness of the base metal and the welded joint is lower than the microhardness before the heat treatment.