Some basic aspects of geometrical characteristics of pulsed current vertical-up GMA weld

The performance of pulsed current gas metal are welding (GMAW) in vertical- up position has been studied in reference to thermal behaviour of the dropl et at the time of deposition affecting the geometrical characteristics of w eld deposit. A more realistic estimation of heat generation at tip of the f ilter wire has been worked out by modifying its resistive heating component using effective current (RMS value) of the pulse current wave. The estimat ed rate of heat generation and measured burnoff rate of the filler wire are correlated to a factor phi defined as summarised influence of pulse parame ter such as peak current, base current, pulse duration and pulse frequency. Analysis of heat balance in between the heat generated at tip of the fille r wire and heat consumed in melting the volume of filler wire fed to the ar c indicates that the temperature of droplet decreases with the increase of both phi and mean current. The variation in pulse parameters affects the we ld geometry by maintaining a good correlation with factor phi. In considera tion of these correlations, a qualitative understanding over the control of purse current GMAW process in vertical-up position, affecting weld geometr y has been developed.