PC-GMAW effect on the welding thermal cycle and weld metal geometry for high strength steels
Résumé
Welding of medium carbon alloy steels used in the manufacture of special-purpose machinery imposes to solve two mutually exclusive problems-to increase the depth of penetration of the base metal and to reduce the width of the thermal impact zone of the welded joints. To successfully solve this problem, it is necessary to use arc welding processes with a concentrated heat source. One of these processes is pulsed current gas metal arc welding (PC-GMAW). The present researches have allowed establishing, that with PC-GMAW change of welding current is a difficult character, namely: on high-frequency impulse signal (60 kHz), impulses of the current of low frequency (from 90-150 Hz) are imposed. The change in the values of the mean welding current at PC-GMAW is achieved by increasing the pause current and the frequency of high-amplitude current pulses. It is shown that the PCGMAW allows reducing the amount of metal splashing, to increase the depth of penetration (almost 2 times) in comparison with stationary welding. At the same time, the cooling rate of HAZ metal in the temperature range 600-500°C decreases almost 1.5 times, which allowed to reduce the width of HAZ by 40%.
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