Patent ID: 7397015

Claim:
A method of forming a root bead in a gap between spaced ends of at least one workpiece, said gap including an open root, said method comprising: a) selecting a metal cored electrode, said metal cored electrode including a metal sheath and core materials, said core material including at least about 0.5 weight percent alloying agent no more than about 2 weight percent slag forming agent; b) advancing said metal cored electrode at a given wire feed rate toward said open root to weld said ends together by at least partially filling said open root in a first weld pass; c) creating a welding current with a controlled short circuit waveform, said short circuit waveform including a succession of welding cycles each having a short circuit portion and a plasma arc portion; d) moving said metal cored electrode along said open root as said welding current is passed through said metal cored electrode to melt the metal cored electrode and transfer the melted metal cored electrode to said ends in said open root to form a root bead, said root bead having an upper surface that includes little or no slag; and, e) applying a shielding gas to at least partially protect molten metal in said open root from the atmosphere.