Process Description:

In submerged arc welding, the ending of a continuous bare wire electrode is inserted into a mound of flux that covers the area or joint to be welded. An arc is initiated and a wire-feeding mechanism then starts to feed the electrode wire towards the joint at a controlled rate, and the feeder is moved automatically or manually along the weld seam. For machine or automatic welding, the work might be moved beneath a stationary wire feeder.

Additional flux is constantly fed in front of and around the electrode, and constantly distributed over the joint. Heat evolved by the arc melts some of the flux progressively, the end of the wire, and the adjacent edges of the base metal, making a pool of molten metal beneath a layer of liquid slag. The melted bath near the arc is in a highly turbulent state. Gas bubbles are rapidly swept to the surface of the pool. The flux floats on the molten metal and totally shields the welding zone from the atmosphere.

The liquid flux might conduct some electric current among the wire and base metal, but an arc is the predominant heat source. The flux blanket on the top surface of the weld pool prevents atmospheric gases from contaminating the weld metal, and dissolves impurities in the base metal and floats and electrode them to the surface. The flux might also remove or add certain alloying elements to or from the weld metal.

Since the welding zone progresses along the seam, the weld metal and then the liquid flux cool and solidify, making a weld bead and a protective slag shield over it.