Concurrent influence of ultrasonic vibration and controlled pulse current on plasma arc behaviors

The controlled pulse welding current combined with ultrasonic vibration was used to increase the keyholing/penetrating capability of plasma arc, and a mathematical model was developed to elucidate the underlying mechanism of periodic interaction between the ultrasound field and the plasma arc. The exerted ultrasonic vibration on the tungsten electrode increases the thermal conductivity of plasma arc, reduces the electrical conductivity of plasma arc, and then enhances the heat-pressure of plasma arc. The variations of the heat flux, current density, and the plasma arc pressure with time were quantitatively analyzed. Compared with the traditional controlled pulse plasma arc welding, the plasma arc heat flux, plasma arc pressure, and gas shear stress on the anode surface all increase in both peak and base stages of welding current after ultrasonic vibration is applied, which improves the keyholing/penetrating ability of plasma arc under the controlled pulse current. The experimental measurements were made to validate the numerical model indirectly.

Automated summary

The combination of controlled pulse welding current and ultrasonic vibration enhances the keyholing/penetrating capability of plasma arc. The mathematical model explains the increase in heat flux, pressure, and gas shear stress of the plasma arc after ultrasonic vibration is applied, validating the model through experimental measurements.