采用碟片激光对3 mm厚TC4钛合金锁底接头进行焊接, 通过分析气孔特征, 判断了气孔类型, 研究了脉冲激光焊、激光热导焊、激光散焦-高速焊三种方法对气孔的抑制效果。结果表明, 锁底接头焊缝中心存在大量气孔缺陷, 气孔形状不规则、尺寸较大、孔壁表面粗糙, 主要为小孔型气孔。采用脉冲激光焊, 在较低的焊接速度和合适的脉冲频率下, 可以将气孔率降至0.5%～1%; 采用激光热导焊, 焊接速度0.4 m/min, 离焦量＋15 mm, 气孔率为0%, 但焊接变形较大、易出现未焊透; 采用激光散焦-高速焊, 随着焊接速度和离焦量的增大, 气孔率明显减小, 焊接速度2～3 m/min, 离焦量＋5～＋7 mm, 气孔率在0%～0.5%, 气孔抑制的效果显著且稳定。

TC4 titanium alloy bottom-locking joint with a thickness of 3 mm was welded by disk laser. The type of porosity was judged by analyzing the pores characteristics. The suppress effects of porosity were studied by using three welding methods: pulsed laser welding, laser heat-conduction welding and defocused laser beam-high speed welding. The results show that a large number of porosities exist in the center of the weld, the porosity is irregular and large, and the surface of the porosity wall is rough, mainly for small pores. By using pulsed laser welding with lower welding speed and appropriate pulse frequency, the porosity is decreased to 0.5%～1%. By using laser heat-conduction welding with 0.4 m/min of welding speed, ＋15 mm of laser beam defocusing distance, the porosity is 0%, but the welding deformation is large and incomplete penetration defect is possibly formed. By using defocused laser beam-high speed welding, the porosity is obviously decreased with higher welding speed and longer laser beam defocusing distance. At the parameter of 2～3 m/min of welding speed, ＋5～＋7 mm of laser beam defocusing distance, the porosity is 0%～5%, and the porosity is significantly and stably suppressed.