The Effect of Shielding Gas and Arc Voltage on the Bead Shape and Pore Generation of Galvanized Steel Pipe Welds with Gas Metal Arc Welding

Abstract

The present study was carried out to investigate the effect of shielding gases (Ar, CO2, Ar+5%CO2, Ar+10%CO2, Ar+20%CO2, Ar+2%O2, Ar+5%O2 and Ar+10%O2) and arc voltage (16-24V) on the bead shape and porosity formation of galvanized steel pipe welds made by a gas metal arc welding process. It was confirmed that the bead height was lowered and bead width was wider with increasing voltages. Bead shapes made by Ar was narrow and convex due to a high surface tension while those made by mixture gas compositions such as Ar+CO2 and Ar+O2t became wider and smoother due to a lower surface tension. The pores were generated the least at low arc voltages of 16-20V and they were more formed over 22V. It was confirmed that Ar produced the most porosity while active and mixture gases such as CO2 and Ar+10%CO2 , Ar+5%O2 and Ar+10%O2 produced little pores by forming ZnO in the weld pool.