Improving Surfacing Performance with GMAW

 

This paper presents a new technique for the production of a coating using the GMAW process, fulfilling two important requisites for this type of operation: low dilution and high productivity.  The use of negative polarity (CC-) would be the appropriate solution.  However, the drawbacks of its use outweigh the advantages.  For this reason only a small part of its power is used in practice, through the application of rectangular wave alternating current. In this technique the time for which negative polarity remains is limited to within the period of transfer of each drop. In the technique presented herein the negative polarity time extends beyond the drop transfer period and becomes associated with the oscillation motion of the torch.  The aim is to solve the drawback of negative polarity associated with its poor wettability. On applying the technique proposed herein, referred to as SP-GMAW (Synchronized Polarity – Gas Metal Arc Welding) the weld beads produced by torch oscillation have positive polarity at their edges. Thus, the geometry is suitable for anchorage of the next bead, avoiding fusion failures. 

 

 

Keywords: GMAW; Cladding; Welding Mechanization; Weaving; Negative Electrode; Overlay welding. 

 

Dutra, J. C.; PUHL, E. B.; BONACORSO, N. G.; SILVA, R. H. G. Improving Surfacing Performance with GMAW. Welding Journal, v. 92, p. 42-47, 2013