Enhancing plasma arc penetration ability with radial gas flow

Enhancing penetration ability is a critical issue in plasma arc welding (PAW). A novel welding torch is developed to create a secondary compression by adding a radial gas flow below the nozzle of the PAW torch, which acts on the plasma arc in the vertical direction. The role and action mechanism of radial gas is studied by experimental test and simulation calculation. Adding the radial gas will enhance the arc column contraction, resulting in increased arc pressure and voltage; simulation results indicate that the addition of radial gas improves the physical characteristics such as arc plasma velocity, temperature, current density, magnetic flux intensity, and radial Lorentz force when compared with conventional PAW; spot welding proves that the re-constricted plasma arc with radial gas achieves greater penetration depth. These findings suggest that the addition of radial gas flow is an effective method for controlling and improving the penetration ability of the plasma arc.