Experimental investigation on the Effect of Wire-laser distance on the Metal transfer Mode and Weld geometry in CO2 laser-gas Metal arc (gMa) hybrid Welding
F-D. Liu, S-Y. Liu, H. Zhang and Y. Shi
In this work the CO2 laser-gas metal arc (GMA) hybrid welding technique is used to weld high strength steel and optimized processes parameters are obtained. In order to make clear the forming process of weld shape, the effect of distance between laser and arc (DLA) on the cross-section morphology of welds, electric signals, arc characteristic and droplet transfer behaviour were studied. When DLA is between 0 and 2 mm “cocktail cupshaped” weld joints form. However, when DLA is between 2 and 6 mm “cone-shaped” welded joints with maximum effective join area are formed. The welding electric signals of hybrid welding processes are quantitatively described and analysed. When DLA is between 2 and 5 mm the results indicated that the probability density distribution of arc current converges toward centre, which favours the stability of the droplet transfer and hybrid welding processes. The droplet transfer mode is changed from globular transfer to projected transfer with the increasing of DLA. Projected transfer mode is benefit for the stability of hybrid welding processes.
Keywords: CO2 laser, laser-gas metal arc (GMA) hybrid welding, arc characteristics, droplet transfer, electric signals