采用Nd:YAG连续激光器对2 mm厚NiTi形状记忆合金(SMA)进行激光焊接。研究了激光焊接过程中激光功率、焊接速度、离焦量、侧吹保护气流量等主要工艺参数对焊缝成形的影响。结果表明,激光功率、焊接速度、离焦量等工艺参数的合理匹配是实现NiTi合金良好焊缝成形的关键因素。线能量为59～75.6 J/mm时能获得最佳焊缝成形;离焦量在-2～3 mm时均能使厚度2 mm NiTi合金试件焊透,其中离焦量在0～1 mm可以得到最佳焊缝成形;当侧吹气流量为15～20 L/min时,气体保护效果和焊缝成形最好。通过大量工艺实验得到2 mm厚NiTi合金焊接速度与激光功率的不同匹配对焊缝成形影响的曲线,为NiTi合金焊接加工及工程应用提供参考。

Nd:YAG laser was used to weld 2 mm thick tapes of NiTi shape memory alloy (SMA). The effect of main welding parameters including laser power, welding speed, defocusing amount, gas-assisting blowing on weld shaping was investigated. The results show that appropriate matching of main welding parameters is the key of realizing good weld shaping. Linear heat input between 59～75.6 J/mm can acquired optimal formation of welds. The defocusing amount between -2～3 mm can relize full penetration of 2 mm thick tapes of NiTi alloys. The defocusing amount between 0～1 mm can obtain the optimal formation of welds. The protective effectiveness and the weld formation is the best when side-blow shielding gas flow rate is from 15 to 20 L/min. Different matching of laser power and welding speed effecting on different formation of welds were experimentally acquired which supply references to laser welding and engineering application for NiTi alloy.