METHOD AND APPARATUS FOR FORMING A ROOT BEAD BY A SUBMERGED ARC WELDING PROCESS

摘要

This disclosure relates to a method and apparatus for welding a root bead in a gap between two relatively thick plates by a submerged arc welding process. An arc is formed by moving the welding electrode parallel to and closely adjacent the gap, and the welding current is alternated between a background current level and a higher or peak current level. The peak current level is high enough to heat and melt the lands at the bottom of the groove between the two plates, and the background current level is sufficient to deposit filler metal to form the root bead without cracking or burning through the root bead. After the root bead has been formed, the groove is filled by depositing additional filler metal.