The Influence of Oscillation Parameters on the Formation of Overhead Welding Seams in the Narrow-Gap GMAW Process

Thick-walled X80 pipelines for oil and gas transportation are difficult to relocate due their large size. In the process of narrow-gap overhead welding, welding defects, such as bulges lack sidewall fusion, can appear easily. To avoid these defects improve quality thick-walled pipelines, GMAW method is adopted in this paper. The formation characteristics weld influence arc oscillation parameters, width dwell time, on seams studied. research, it was found that, NG-GMAW position, there a downward trend middle formed surface pool. Defects, finger-shaped penetrations were prone occur gravity. increased beneficial reducing protrusion seam, but an excessive easily cause undercut defects. time has little effect increase penetration, thereby avoiding occurrence incomplete penetration.