Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 03, 2017 - September 06, 2017
In fusion welding, gravity makes molten metal flow downward and it sometimes causes an irregular-shaped weld bead and weld defects. This problem makes it difficult to conduct high-quality and high-deposition rate welding. To solve this problem, the authors propose an ECMP (Electromagnetic Controlled Molten Pool Welding Process) method which controls the molten metal flow by using an upward electromagnetic force. Based on this concept, the ECMP method has already been put into practical use for multipass welding of thick plates in horizontal and vertical positions in an LNG tank with a high-deposition rate. As to flat and overhead positions welding, the upward electromagnetic force can be acquired by adding the magnetic field and this upward force can lift the molten metal up under some restricted conditions, resulting in the remarkably improved shape of a penetration bead. Incidentally, although the conventional ECMP method has prevented molten metal from sagging downward using an upward electromagnetic force, the authors examine using a downward electromagnetic force in this study. Utilizing the downward electromagnetic force, improvement of the weld penetration in TIG welding processes of thick plates can be anticipated. In this paper, the authors investigate in detail the influence of the downward electromagnetic force on the flow and temperature of the molten pool.
