Stability of Double Wires Narrow-gap Gas Metal Arc Welding

Some special parameters of double wires narrow gap GMAW (NG-GMAW) welding can be adjusted individually, such as the angle and distance between the two wires along the welding direction and the distance between the wire and the sidewall of the groove. These parameters have great influence on the welding stability. Experiments results show that when the distance between the two wires is less than 15 mm or greater than 50 mm, the two welding arcs are in one molten pool or two independent molten pools, and the welding process is very stable. When the distance is 20-30 mm, the molten pool is transforming from single one to two independent one. Under the action of unbalanced electromagnetic force, the arc is compelled to break frequently and the stable welding process is destroyed. When the two wires are parallel along the welding direction, the welding process is stable; if the front wire is inclined to the rear wire, the wandering of the front arc is aggravated. The distance between the wire and the groove sidewall has great influence on the arc modality. When the distance is 2.5 mm, the arc burns stably between the wire and the sidewall as well as the bottom of the groove. But if the distance is less than 1.5 mm, the arc burns between the sidewall or bottom randomly, and the welding stability deteriorates.