Double-wire tandem GMAW welding process of HSLA50 steel

Abstract

Tandem welding process employs double wire feed in a single torch, providing increased deposition rate and consequent reduction in process times. However, the process complexity increases since an optimum combination of parameters is essential to avoid the occurrence of interference between both electric arcs. Such interferences may result in hindering stability of the welding process, leading to poor weld bead geometry. To address this problem, the present investigation proposes an approach to reduce the number of arc’s inconsistencies during welding of a 15-mm HSLA50 steel plate with ER70S-6 wire. Three configurations were tested considering high-current ratings in lead and trail wires: pulsed-pulsed waves (torch angle: 90°), continuous-pulsed waves (torch angle: 90°) and continuous-pulsed waves (torch angle: 80°). In the three cases, the welding arc voltage and currents were acquired, and penetration profile and the dimension of the heat affected zone (HAZ) evaluated. Microhardness testing was utilized to investigate the mechanical strength of the HAZ. The best combination of parameters was found considering the three welding conditions tested in this study, where the lead wire was parameterized in constant voltage mode and the trail wire in pulsed spray metal transfer with a torch angle of 90 ° from the workpiece. 20% higher displacement speed of the robot and no occurrence of inconsistences in the electric arcs were accomplished.