Influence of Interwire Distance and Arc Length on Welding Process and Defect Formation Mechanism in Double-Wire Pulsed Narrow-Gap Gas Metal Arc Welding

The effects of interwire distance (d) and arc length correction coefficient (C-c) on the arc behaviors, droplet transfer and welding process stability in the double-wire narrow-gap gas metal arc welding (NG-GMAW) were investigated. With d changing from 10mm to 20mm, the arc deflection only occurs at the background stage of pulsed welding current, and the droplet transfer mode keeps unchanged. A large C-c (20%) leads to serious peak arc deflection and unstable droplet transfer, whereas a small C-c (- 10%) eliminates the arc deflection and brings about short-circuiting droplet transfer. The arc interruption frequently occurs when d is 20mm or C-c is 20%. Moreover, when d is 10mm or C-c is 20%, serious sidewall arcs occur in double-wire NG-GMAW. With the increase in d and/or decrease in C-c, the welding process stability can be improved at first and then gets worse. In general, the trailing arc is more stable than the leading arc. Increasing C-c will result in a serious surface depression defect on the left side of the weld bead because of the serious peak arc deflection. A sound weld bead is obtained when the interwire distance is 15mm.