Heat Transfer in Pulsed Gas Metal Arc Welding

The heat transferred to the workpiece during direct current, electrode positive pulsed gas metal arc welding (GMAW) was measured and related to pulse parameters and other process variables using in-process high speed weld video, electrical signal analysis, and calorimetry techniques. Arc efficiency of pulsed GMAW was determined as a function of heat input and arc length for various combinations of peak current and duty cycle. The methodology for relating the arc efficiency of pulsed GMAW to constant voltage and constant current GMAW was also investigated. The arc efficiency of pulsed GMAW varied inversely as a function of heat input, but was approximately 73% over the range of heat inputs evaluated in this study. It was also shown that under certain conditions constant voltage, constant current and pulsed current (PC) processes exhibit equivalent arc efficiencies when the weld heat input is the same.