Effects of single and double pulses on microstructure and mechanical properties of weld joints during high-power double-wire GMAW

High-power double-wire gas metal arc welding (GMAW) experiments were conducted with the single and double pulses technology. The effects of single and double pulses on the weld bead formation, microstructure and mechanical properties of the weld joints were investigated. The experimental results demonstrated that through the high-power double-wire single and double pulsed GMAW stable welding could be achieved. Also, the high quality weld beads were acquired with slight spatter, without undercut or hump. Double-wire double pulsed GMAW was more stable, producing more perfect weld shape and higher microhardness compared to double-wire single pulsed GMAW. The stirring effect of alternating strong and weak pulses on the weld pool during the double-wire double pulsed GMAW could produce significant fish-scale ripples and refine the grains, resulting in finer grain microstructure with higher hardness. The results proved that the low-frequency pulse cycle controlled the formation of each weld pool precisely. This meant that a weld pool was formed in a low-frequency pulse cycle.