Research on the Use of Robotized Tandem MAG Welding in Steel Plates Destined for the Manufacture of Pipelines

Abstract

The performed research focuses on the complete replacement of the pipeline manufacturing process consisting in welding on SAW+MIG / MAG generators with the robotized Tandem MIG / MAG welding procedure, with low energy consumption.The Tandem MAG procedure was experimented on X52 MS steel plates destined for the manufacture of pipelines, measuring 400x150x12 mm, with Y-joints (30o).The welded joints were executed horizontally and unilaterally, with flux bed support, 3 welding seams, using for filler material two wires of the same quality, EN ISO 14341: G 42 4 M G3Si1 (Filcord C), measuring 1.2 mm in diameter, and shielding gas EN ISO 14175 (CORGON 18).The entire technological welding process was carried out in fully robotized, laboratory conditions, using the QIROX -315 welding robot, fitted with Tandem MIG/MAG welding equipment, type QUINTO-GLC 603.The welding seams were executed with the same Tandem MAG welding head, with two wires, taking advantage of the possibility to rotate the welding head so as to obtain welding seams with the wires either positioned one after the other (tandem), or transversally (perpendicular to the welding direction), obtaining, by correlation with the welding speed, optimal linear energies, implicitly, seams of various widths and penetrations.The results of the tests concerning the characterization of the obtained welded joints corresponded to the mechanical – metallographic tests, falling within the ranges provided by the applicable standards.The welding parameters used in the robotized Tandem MAG procedure may lead to remarkable advantages concerning the use of energy and filler metal. Thus, linear energies are about 40% - 45% smaller than in the case of the classical SAW+MIG / MAG process, with positive effects on the mechanical and metallographic characteristics of the welded joints, leading to significant reductions in energy consumption. Furthermore, the use of filler materials (wire, shielding gas) decreases by 10% - 15% as compared to the classical SAW+MIG / MAG process, leading, implicitly, to lower costs.As a consequence of the obtained results, MAG Tandem welding procedure may become an alternative to SAW submerged arc welding and combined SAW and MIG / MAG welding and a classical reference method for the manufacture of pipelines