Numerical analysis of hybrid plasma in fiber laser-arc welding

Abstract

A 3D non-axisymmetric hybrid plasma model in fiber laser-arc welding is developed, in which the laser induced plasma is considered as ejecting vapor from keyhole with specific radius, temperature and velocity. The effects of the ejecting vapor temperature and velocity, and the distance between laser and arc are simulated and discussed. From the simulation results, the height of the laser induced plasma is higher with lower ejecting vapor temperature, bigger ejecting vapor velocity and larger distance between laser and arc. The temperature of the hybrid plasma decreases compared with the temperature of arc plasma under all the simulation parameters, which is very benefical to reduce distortion resulted from bigger heat input. The current density of the hybrid plasma has a complex dependence on the studying parameters. When the ejecting temperature is 10 000 K, or the ejecting velocity is 50 m s−1 or distance between laser and arc is 4 mm, the current density in the laser-induced-plasma affected zone is larger than that of the arc plasma at the same position, while it becomes smaller under other simulation parameters. In addition, the current becomes more concentrated with lower vapor temperature, larger vapor velocity and smaller distance between laser and arc.