Effects of welding current and torch position parameters on minimizing the weld porosity of zinc-coated steel

Abstract

This study involves an investigation of the effects of the welding current and torch position parameters, including the travel angle, torch-aiming position, and work angle, on reducing the weld porosity in the cold metal transfer (CMT) welding of hot-dip galvannealed steel in the lap-joint configuration. The effects of the welding parameters on the weld porosity are investigated through statistical analysis, high-speed imaging of the weld pool behavior, welding signal analysis, and scanning electron microscopy (SEM) analysis. The magnitude of the welding current influences the weld porosity and weld pool behavior because the current determines the arc force, the heat input, the amount of zinc vaporization, and the weld pool viscosity. The torch position parameters also have considerable effects on the weld porosity because they determine where the arc, arc force, and heat input are concentrated. A response surface model relating the welding parameters and the amount of weld porosity is estimated, and the optimum welding conditions and a suitable welding range are determined on the basis of the estimated model to minimize the weld porosity in the CMT welding of hot-dip galvannealed steel.