Alternating current-gas metal arc welding for application to thick plates

An alternating current (AC)-gas metal arc welding (GMAW) process with an improved current waveform is proposed. In this process, an increase in the welding current and electrode negative (EN) ratio resulted in finger-like penetration. Concentrated heat input was observed at the center of the weld pool at high current, and this input increased with the EN ratio. The lack of fusion at the joint side walls, which was observed for plates thicker than 5 mm, can be overcome by rapid pre-heating of the joint sides through induction heating. The effectiveness of using the AC-GMAW process under the strong magnetic fields of induction heating was evaluated in comparison with the pulsed-GMAW process. The proposed approach, by utilizing the benefits of a higher material deposition rate and controlled heat input, can be used to apply the AC-GMAW process to workpieces of greater thickness. (C) 2015 Elsevier B.V. All rights reserved.