The effect of pulsed frequency on the plasma jet force with ultra high-frequency pulsed arc welding

Abstract

Plasma jet force is considered to be the key component of the arc force during arc welding. This is known to be the important factor for surface penetration into the molten pool. With pulsed welding technology, the arc plasma constricts significantly which affects the plasma jet force. The experimental results in this work indicate that the arc force increases with increasing pulse frequency. The plasma jet force is found to be the most important contributor to a larger arc force during ultra high-frequency pulsed gas tungsten arc welding (UHFP-GTAW). In this work, the reason for the increasing force is studied with support from a mathematical model. The plasma jet force was recognized to change with the distribution coefficient a at various pulse frequencies. With increasing frequency, the value of the distribution coefficient decreases. As known, the distribution coefficient represents attenuation of the curve. The results suggest that with a high pulse frequency, a high level of plasma jet force occurs in a constricted arc plasma and significant attenuation of the plasma jet force can be found. In contrast, the plasma jet force was low with little attenuation during conventional gas tungsten arc welding (C-GTAW).