Modification of droplet morphology and arc oscillation by magnetic field in laser-MIG hybrid welding

In this paper, we presented the morphological characteristics of droplet and arc during alternating magnetic field assisted laser-MIG welding. High speed camera was used to map the effect of magnetic intensity and frequency on droplet transfer and arc shape. Results revealed that the magnetic field indeed modified droplet morphologies and hence pointing direction. This appearance was mainly attributed to the centrifugal force during droplet spinning and resultantly reduced effective potential energy (mechanism I). Moreover, combined effect of laser and magnetic field induced a regularly altered axial asymmetry of arc along the welding direction. Cause of this arc oscillation was due to particle packing effect in one side during laser-MIG welding (mechanism II). At last, the optimum magnetic field parameters during the laser-MIG parameters (2000 W, 150A and 1.1 m/min) was concluded as B(mT)/f(Hz) <= 0.8 and f(Hz) > 1/2t(0).