Heavy section welding - Narrow groove welding

Narrow groove welding was developed to make narrow welds in thick materials. The gas metal are process is used in the spray mode to join plates from 1 to 12 in. thick with root openings 3/8 to 5/8 in. wide - Fig. 1. The process allows relatively fast welding on heavy-section carbon and low-alloy steels, minimizing distortion. Either a square-groove edge preparation or a V groove with a minimal groove angle is used. One of the requirements of narrow groove welding is the necessity for the electrode to fit into the full depth of the groove so that complete sidewall fusion can occur. Some special wire feeding mechanisms have been devised to accomplish this - Fig. 2. Welding wires ranging from 0.9 to 1.6 mm (0.35 to 1/16 in.) have been used with narrow groove welding. Typically, ten welding passes will fill a 25-mm (1-in.) deep groove. Deep-groove welding has some very important advantages. Since thick sections are joined at a fast pace and with minimal filler metal, the process can be economical. The fast travel speed reduces heat input, which has a positive effect on mechanical properties and the heat-affected zone. Distortion can be controlled with this process and the whole operation can be automated.