Influence of Push and Pull Techniques on High-Speed Buried-Arc GMAW Process

Abstract

The GMAW torch orientation, whether pulling or pushing, influences both arc welding and hybrid processes. In hybrid laser-arc welding, for example, when the torch is pulled, a greater bead penetration is obtained. To promote greater penetration, the literature also indicates the use of a buried arc in GMAW, although it was initially developed to only operate with a vertically-positioned torch. Therefore, this work aims to investigate the influence of the push and pull techniques on the behavior of buried-arc GMAW at high welding speeds. Welds were performed with the push and pull techniques under the following conditions: buried and unburied (long) arc with welding speeds of 1.0, 1.5 and 2.0 m/min and current ranging from 450 to 470 A. The process tends to be more stable when pulling than when pushing (buried or long arc). Evidence of instability was only identified for the pushed buried arc, due to material accumulation at the front region of the molten pool, for the higher welding speeds. Only the 1.0 m/min buried-arc processes resulted in beads with an appropriate surface finish.

Buried Arc application in Hybrid Laser-Arc Welding of Thermo-Mechanical Control Process Steels

“…According to Kutsuna and Chen [8], the deeper the laser incidence region in the molten pool, the greater penetration expected for the HLAW process. As in the GMAW process with buried arc the weld pool has a deeper pro le [3], the thickness of material to be penetrated by the laser is smaller, allowing the application of a lower laser power to achieve full penetration. This behavior is illustrated in Fig.…”

“…In this case, the arc is established in a depression in the center of the molten pool, increasing the penetration and enabling higher welding speeds. The GMBAW also has high deposition rates, due to the high wire-feed speeds required to keep the short arc length and to the high currents combined with a long stick-out, which assist in wire fusion [3]. These characteristics of GMBAW can also be bene cial when applied in HLAW, since the deep depression formed by the pressure of the arc would reduce the thickness perceived by the laser beam, improving weld penetration.…”