CORROSION BEHAVIORS OF ND: YAG LASER-GMA HYBRID WELDMENT OF AA5052-H32 Al ALLOYS

This paper investigated the corrosion behaviors of the Nd: YAG laser-gas metal arc (GMA) AA5052-H32 weldments comparing with the base alloy. The corrosion susceptibility of weldments was higher than that of the base alloy. The weld fusion zone (WFZ) suffered the severe pitting in acidic chloride media. The zones adjacent to the weld fusion boundary showed less corrosion tendency. A corrosion cracking was associated with pitting in the weldments. The surface morphology observation and composition analysis were investigated by the scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy. At the WFZ/HAZ interface and the HAZ/base alloy interface, the galvanic corrosion coupling existed. From the comparison, the WFZ showed anodic behavior, the zone adjacent to the weld fusion boundary showed cathodic behavior. The corrosion of WFZ was progressed by the formation of the galvanic couples.