Effect of ambient atmosphere on penetration geometry in single laser and laser-arc hybrid welding. Welding phenomena in hybrid welding using YAG laser and TIG arc (second report)

摘要

In this study the effects of ambient atmosphere upon the penetration depth and the fusion zone geometry were investigated. The results may be summarised as follows: Welding using a laser alone and hybrid welding at 100 A and 200 A arc currents were carried out where the oxygen ratio of the Ar shielding gas was varied from 0 percent-15 percent within the enclosed chamber. The results revealed that, in every case, the fusion geometry is influenced by oxygen. During welding using a laser alone and hybrid welding at 100 A arc current the upper zone fusion width gradually decreased and the penetration depth increased with increasing oxygen ratio within the atmosphere; by contrast, during hybrid welding at 200 A arc current the penetration depth did not increase even for the increased oxygen ratio and the penetration (at the nail head) of the upper part of the fusion zone substantially increased. It was clarified during similar experiments in which the shielding gas and the atmosphere were changed to He that changes in the weld geometry occurred in response to the oxygen ratio, even in the He atmosphere.