激光深熔焊接过程的稳定性与焊接时的金属蒸气动力学行为密切相关。采取特殊试验方法对高功率激光深熔焊接小孔内喷出的金属蒸气流力学特性进行研究, 观察分析了在金属蒸气流的推动作用下自由下落金属球的速度变化以及从小孔飞出的飞溅熔滴速度大小。结果得出, 激光深熔焊接过程中激光功率越大、离小孔开口处距离越小, 由小孔喷出的金属蒸气流的推力越大; 相同激光功率焊接时, 飞出小孔的飞溅具有的速度和动能远大于金属蒸气推动金属球获得的速度和动能增量, 揭示了飞溅在飞出小孔前已经获得较大动能。由此得出, 相比于小孔内高压蒸气流和流动的焊接熔池熔液的动力学作用, 从小孔喷出后的金属蒸气流的推动作用甚微。

The process stability has a close relationship with the dynamics behavior of metallic vapor during deep penetration laser welding. A special experiment was designed to study the dynamic characteristic of metallic vapor when it was ejecting out from the keyhole outlet during high power deep penetration laser welding. In the experiment, the velocity of free falling metallic ball pushed by the ejecting metallic vapor and the velocity of splatter were investigated and compared. It was concluded that the thrust of ejecting metallic vapor increases as the laser power increases or the distance from the keyhole outlet decreases. At the same welding condition, the velocity and kinetic energy of splatters are much higher than the increments of velocity and kinetic energy of falling metallic ball which is pushed by the ejecting metallic vapor. This reveals that the splatter has gained more kinetic energy before it is splashed out of the keyhole. Thus, in general, it could be concluded that the push effect of ejecting metallic vapor is smaller than the dynamics effect of the high pressure vapor inside the keyhole and the dynamic molten pool during deep penetration laser welding.