TIG welding is one of the welding methods widely used in industries for high reliability of joints, little occurrence of spattering and high convenience of construction. However, compared with other arc welding methods, there is a disadvantage that depth of penetration is sallow. To solve this problem, the authors propose a new ECMP (Electromagnetic Controlled Molten Pool Welding Process) method which controls the molten metal flow by using electromagnetic forces generated in the molten pool by a magnetic field perpendicular to the unidirectional current.

Incidentally, although the conventional ECMP method has mostly prevented the molten metal from sagging downward by using an upward electromagnetic force, the authors propose the use of a downward electromagnetic force in this study. When the direction of the magnetic field is reversed from the conventional method, in principle it is possible to obtain a downward electromagnetic force in the direction of gravity. Utilizing the downward electromagnetic force, improvement of the weld penetration in the TIG welding process of thick plates can be anticipated.

In this paper, the authors describe in detail their investigation of the influence of the generated downward electromagnetic force on the molten pool flow, the molten pool surface temperature, and the final bead shape when using the new ECMP method which forcefully uses such a downward electromagnetic force.