A novel AC-TIG of aluminium by controlling cathode spot behaviour through the application of an external magnetic field

This study aims to increase the penetration depth of an aluminium (A5052) weld pool in alternating current tungsten inert gas welding by controlling the cathode spot behaviour through the application of an external magnetic field. The external magnetic field direction was parallel to the base metal surface and perpendicular to the welding direction. The heat input from the distributed cathode spots was experimentally investigated using a high-speed video camera. The penetration depth almost doubled as a result of applying the optimal magnetic flux density of 5.5 mT. At this magnetic flux density, the largest number of cathode spots was concentrated in the weld pool, causing intensive heat input owing to the large cathode fall voltage and consequently leading to deeper penetration.