Influence of high-frequency pulse on droplet transfer process and weld formation in double-wire median pulsed GMAW of aluminum alloy

Abstract

A double-wire median pulsed gas metal arc welding (GMAW) with a high-frequency pulse waveform was developed to study the influence of a high-frequency pulse on the droplet transfer process and weld formation in aluminum (Al) alloy. The droplet transfer process was recorded using a high-speed photography system. At the same time, the influence of a high-frequency pulse at peak stage was investigated. The experimental results demonstrated that stable droplet transfer and continuous welds are obtained by incorporating high-frequency pulses. The high-frequency pulses increase electromagnetic force and facilitate premature detachment of droplets. Especially, at a high frequency of 20 kHz, one drop per pulse (ODPP) droplet transfer mode is achieved, which is the ideal mode. In addition, high-frequency pulses increase axial arc pressure, strengthen convergent flow, and reduce the effect of divergent flow, resulting in increased weld penetration while decreasing weld width and porosity.