Cold wire gas metal arc welding: Droplet transfer and geometry

Abstract

The metal transfer dynamics induced by cold wire additions were examined during the three natural transfer modes in welding: short circuit (low arc power), globular (intermediate arc power), and spray (high arc power), and their implications on weld bead geometry, dilution, and melting efficiency were evaluated during cold wire gas metal arc welding (CW-GMAW). Bead-on-plate welds were conducted on Vs-in. (9.52-mm) -thick AISI1020 steel plates. Data acquisition of the electrical signals were synchronized with highspeed imaging to study the arc dynamics. Standard metallographic procedures were used to study dilution, allowing the melting efficiency to be estimated. The results provide evidence that increasing cold wire feeding rates will favor arc attachment to the cold wire rather than to the weld pool for all natural transfer modes. This influences dilution of the welds along with the melting efficiency. The findings are used to identify conditions where CW-GMAW offers higher melting efficiency than the standard GMAW process.