Abstract Based on an X-ray imaging system, the characteristic of underwater wet welding droplets was revealed, which was deemed to be the essential factor contributing to the unstable underwater wet welding process. By observing the X-ray images, it is confirmed that the inflation-exhaustion process in the droplet occurred during the entire process from the droplet forming to entering into the molten pool. The void in the droplet leaded to lower gravity and greater repulsive force and deteriorated the welding process stability. On the one hand, the spatter-like droplet transfer mode was relatively easy to occur, increasing the frequency of the droplet repelled spatter. On the other hand, the arc easily broke and the arc stability was deteriorated. In addition, the droplet rupture process tended to promote the generation of gas escaping spatter. The process was effected by material gas solubility, the surface tension, the temperature according to the establishing force models.

中文翻译：

---

熔滴内部特性及其对水下湿焊工艺稳定性的影响

摘要 基于X射线成像系统，揭示了水下湿焊滴的特征，认为这是造成水下湿焊过程不稳定的重要因素。通过对X射线图像的观察，证实了从液滴形成到进入熔池的整个过程中都发生了液滴中的膨胀-耗尽过程。熔滴中的空隙导致较低的重力和较大的排斥力并降低焊接过程的稳定性。一方面，飞溅状液滴转移模式相对容易发生，增加了液滴排斥飞溅的频率。另一方面，电弧容易断线，电弧稳定性变差。此外，液滴破裂过程往往会促进气体逸出飞溅的产生。