功率对纯钛薄片激光封孔成形及接头性能的影响

为实现直径为0.1 mm微孔的良好封接，采用低功率脉冲激光对0.40 mm厚的工业纯钛(CP-Ti Grade 1)进行了封焊，采用扫描电镜、显微硬度计及光学显微镜，研究了激光功率对焊缝表面成形、焊接接头横截面形貌和显微硬度的影响规律，分析了接头的微观组织结构.结果表明：当激光功率不低于19.2 W时，微孔可以实现完全封接，且熔核直径随着激光功率的增大而增大，但随着激光功率增大，焊缝凹陷和烧蚀现象越加严重；当激光功率增大时，焊缝表面显微硬度呈上升趋势，激光功率为19.2 W时，焊缝成形良好，且最大显微硬度值可以达到290 HV；焊缝中心微观组织为针状α、锯齿状α以及板条状α晶，焊缝上边缘为锯齿状α晶，而焊缝下边缘为细小的锯齿状α和针状α晶.
Seal welding of 0.40 mm-thick commercially pure grade 1 titanium with 0.1 mm diameter holes was realized using low power impulse laser. The effects of laser power on the weld geometry, cross-section morphology, microhardness and microstructure of the welded joint were studied by using scanning electron microscopy, microhardness tester and optical microscopy. The results show that when the laser power is no less than 19.2 W, full seal welded joint can be achieved. Nugget size increases whereas welding depression and ablation become more serious with the increase of laser power. Meanwhile, the surface microhardness of the weld bead gradually increases with the increase of laser power. An excellent geometry of the welded joint can be achieved with the maximum microhardness values of 290 HV, when the laser power is 19.2 W. The microstructure of the welded joint consists of acicular α, serrated α and lath α in the weld center, serrated α on the top edge, and the thin serrated α and fine acicular α on the bottom edge of the welded joint.