Abstract: With the high speed camera, the characteristics of thin wire MAG welding process with high current density including arc shape and droplet transfer are researched. Through analyzing the force of liquid metal cone and arc, the motion model of liquid metal cone is given. Also the spatial position relationship and the motion correlation of liquid metal cone and arc are pointed out. The result shows that the motion style of the liquid metal cone belongs to self-magnetic rotating which means the liquid metal cone deviates from the wire axis by a certain angle and makes high speed rotation around the wire axis under the actions of electrode magnetic force and arc force. The relative size of deflection angle of liquid metal cone is determined by the area of liquid metal cone enclosed by the arc shining zone. When this area increases, the deflection angle becomes smaller and the stability of welding process is enhanced. The driving force of high speed rotation of arc is supplied by the magnetic filed of liquid metal cone, and the arc deflection angle and arc rotating angular velocity are closely related to the deflection angle and rotating angular velocity of liquid metal cone respectively.

Key words: Electrode magnetic force, Liquid metal cone, Thin wire high current MAG welding, Al alloy/steel, brazing-fusion welding, Joining of dissimilar materials, joint properties, state-of-art