Effect of coaxial welding wire structure on arc instability in argon shielding gas

Abstract

The instability of gas metal arc welding in pure Ar shielding gas is associated with the structure of the coaxial multilayer solid (CMS) wire. This wire has a coaxial double structure consisting of a different composition in its inner and outer parts. In this paper, four CMS wires were developed to investigate the influence of the wire structure on the welding behaviour. First, the wire melting behaviour was observed with a high speed video camera system. Then, the relation between the welding instability and the length of the column of liquid molten metal, which causes arc instability, was analysed. Next, a wire melting simulation of the CMS wire was carried out to discuss the effect of the wire structure on the melting behaviour. Finally, the welding stability was investigated at the V groove. An excellent bead shape was obtained, and stable welding was found to be possible using an appropriate wire structure.