The 4F welding position refers to the overhead fillet weld, one of the most challenging orientations in the welding industry. In this position, the welder works from the underside of a joint, with the torch or electrode pointed upward. Because gravity constantly pulls the molten puddle away from the metal, achieving a clean, strong weld requires exceptional technique and precise heat control.
The two biggest defects in 4F welding are undercut and overlap. Undercut occurs when the arc melts the base metal at the edges of the weld but doesn't fill it back in with filler metal, often caused by excessive heat or an incorrect torch angle. Overlap happens when the puddle sags and rolls over the surface without fusing, usually due to low heat or slow travel speed. 4f welding position