Suppression of undercut defects in high-speed GMAW through a compound magnetic field

The influence of compound magnetic field on the arc and droplet movement is studied using a pair of high-speed color cameras. An improved vision-based sensing system was employed to capture 2-D image of tracer particle movement on weld pool. An algorithm transforming 2-D image coordinates to 2-D space coordinates was used to determine the velocity of tracer particle. The assisting compound magnetic field is able to decrease the speed of backward fluid flow and promote the transverse spreading of the liquid metal, which is beneficial to suppressing undercut defects in high-speed arc welding. The maximum welding speed can reach up to 1.7 m/min when the welding current is 280A, arc voltage is 32.5 V, excitation current is 6 A and excitation frequency is 15 Hz.