Molten pool behaviors and weld forming characteristics of all-position tandem narrow gap GMAW.

A tandem gas metal arc welding system was utilized for narrow gap welding in three welding positions: flat, vertical down, and overhead welding position. The two arcs worked in two independent molten pools respectively. The molten pool behaviors were investigated and the weld forming characteristics were revealed. The results suggest the molten pool behaviors in different welding positions are different due to the action of gravity. In flat welding position, the molten pool surface is concave. In vertical down welding position, more fusion metal flow to the head of molten pool, and the molten pool is asymmetric, and the molten pool surface is more concave than that in flat welding position. In overhead welding position, more fusion metal flow to the tail of the molten pool, and the surface of the pool is convex. High quality welds for various welding positions can be acquired with an appropriate ratio of welding speed to wire feed speed. [ABSTRACT FROM AUTHOR]