Study on welding process and prosperities of AA5754 Al-alloy welded by double pulsed gas metal arc welding

•DP-GMAW has attracted great attention for its characteristics of stir weld pool.•The penetration depth increases and fluctuates with thermal pulse.•The droplet transfer frequency varied with thermal pulse.•The grain size of the weld joint decreased with the thermal frequency increasing.

In this paper, the effect of double pulsed gas metal arc welding (DP-GMAW) on metal droplet transfer, weld pool profile, weld bead geometry and weld joint mechanical properties of Al alloy AA5754 are presented. A high speed camera was utilized to reveal the metal transfer behavior and weld pool profile. A self-developed electrical signal acquire system was adopted to record the current waveform during welding process. The results indicated that the metal transfer, weld pool profile and weld bead geometry in DP-GMAW significantly differ with P-GMAW. The microstructure showed that grain size of the weld bead decreased with increasing of thermal pulse frequency, and the eutectic precipitates Mg2Si were homogeneously distributed at fusion zone. The mechanical properties of welded joints were improved.