STUDIES ON INFLUENCE OF SOME PULSE PARAMETERS ON WELD THERMAL CYCLE IN PULSED MIG WELDING OF Al-Zn-Mg ALLOY

Abstract

In this investigation the influence of various pulse parameters on the weld thermal cycle in'pulsed MIG welding of Al-Zn-Mg alloy has been studied. The filler wire of composition Al-4.5% Mg has been used for welding. The welding was carried out for mean current of 150, 180 and 220 A and the pulse frequencies employed were of 25, 50 and 100 Hz for three values of pulse duration viz. 4.5, 6.6 and 8.6 ms. The weld thermal cycle has been analysed by determining the peak temperature and the retention time during cooling in solution temperature range (450-350 C), overaging temperature range (250-200 C) and convention aging temperature range (160-130 C). The peak temperature has been found to be affected by the mean current, pulse frequency and pulse duration. At low mean current level the peak temperature in HAZ was found to be higher in comparison to that of at higher mean current. The retention time in above mention temperature ranges has also been found to be affected by mean current, pulse frequency and pulse duration. The micro hardness in HA2 has also been found to be affected by mean current, pulse frequency and pulse duration.