Effects of Welding Positions on Droplet Transfer in CO_2 Laser-MAG Hybrid Welding

摘要

All-position welding is widely used in many industries such as pipeline construction, automobile factory, and shipyard. In this paper, the variations of the droplet transfer at different welding positions, including flat, horizontal, and vertical positions, have been studied by high speed video photography during CO_2 laser-MAG hybrid welding of E36 steel plates. The results indicated that the droplet transfer noted by transfer mode, impact location, droplet diameter, and transfer frequency were significantly effected by the welding positions. With the same welding parameters, at flat and horizontal positions the transfer modes were globular metal transfer, while at vertical position the transfer mode was short-circuiting. At flat and vertical positions the droplet impacted on the weld pool, whereas at the horizontal position the impact location of the droplet could be divided into three types, including drop down, impact under the seam, and impact on the weld pool. At vertical position the mean droplet diameter and the transfer frequency were the largest one and the lowest one at the three positions, respectively. The results also showed that the weld appearance was significantly affected by the welding positions.