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

Abstract

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

Applying Statistical Models to Optimize the Weld Bead Geometry in the Vertical Oscillation Arc Narrow Gap All-Position GMAW

“…In the present study, combined with previous research work [35], it was intended to combine the all-position NG-GMAW method with vertical oscillation arc welding. Then the welding parameters were optimized to achieve the desired sidewall penetration and weld bead shape and reduce incomplete fusion on the sidewall and interlayer.…”

The Influence of Two-Jet Gas Shielding Parameters on the Structure and Microhardness of Steel 45 Joints during Consumable Electrode Welding

“…Steel is still the main structural material, despite the constant increase in the share of light alloys, composites, and polymeric materials in modern products. The demand for the production of welded metal structures, especially from high-strength steel, is constantly increasing, not only in mechanical engineering, but also in other industries [1][2][3][4][5].…”

“…These structures have a high hardness and internal tension gradient that can lead to the development of cold cracks and the dissolution of a permanent joint. Welding processes are influenced by various phenomena and factors that determine their quality and operational reliability [2][3][4]. The process of welding with a consumable electrode in shielding gases is always accompanied by an extreme change of the material in the welding zone and inevitable losses-burnout and oxidation of chemical elements, splashing droplets of molten metal of the welding wire.…”