Hybrid welding with fiber laser and CO2 gas shielded arc

Argon-rich shielding gas was replaced by 100% CO2 gas for cost reduction in fiber laser-GMA hybrid welding of double-side welded T-joints. The welding process using 100% CO2 gas was characterized by a large number of spatters, while the penetration depth of a weld was increased and porosity was reduced. With the objective of obtaining a buried-arc transfer for the reduction of spatter formation, the welding parameters were optimized by observation with a high-speed video camera. Reduced arc voltage, arc leading arrangement and shortened wire extension were necessary to achieve a buried-arc transfer. A significant reduction in spatter generation could only be obtained by the procedure that the relative distances between the two heat sources in the X and Y directions were controlled to produce a proper profile of the arc cavity that could trap any spatters generated. A regulating action of a keyhole was observed to remove the disturbances in the melt flows caused by the arc short-circuiting, and high quality joints with good appearances and very few spatters could be produced.