Dynamic behavior of ultrasonic frequency pulsed current-assisted gas metal arc welding

Investigating ultrasonic frequency pulsed current (UFPC)-assisted welding is crucial owing to its significant advantages over traditional welding methods, including enhanced weld quality, reduced defects, and increased efficiency. This study elucidated the generation mechanism of arc ultrasonic waves influenced by UFPC through theoretical derivation. A microscopic model of arc plasma under the influence of UFPC was developed, and the equations governing the thermophysical properties of the plasma were theoretically derived and calculated. A three-dimensional numerical simulation model was developed to analyze the dynamic behavior of arc plasma and molten metal in UFPC-assisted gas metal arc welding (UFPC-GMAW). The simulation results revealed that the incorporation of UFPC increased both the maximum arc temperature and plasma velocity, resulting in a conical shape of the arc. Additionally, the maximum arc temperature amplitude decreased from 13.6% in conventional GMAW (C-GMAW) to 9.6% in UFPC-GMAW, indicating improved arc stability. The increase in electromagnetic force led to a higher droplet transfer frequency. Moreover, the weld pool in UFPC-GMAW exhibited greater weld penetration than in C-GMAW. Notably, the variations in maximum arc temperature and velocity were synchronized with UFPC, resulting in localized thermal contraction and expansion within the arc. These changes affected the arc volume and shape, leading to the excitation of ultrasonic waves. The calculated droplet size and transfer frequency were consistent with the experimental results, confirming the reliability of the models. These simulation results provide valuable guidance for engineers in designing UFPC-GMAW technology to achieve high-quality welds.