Corrosion Behavior of Dissimilar Metal Weld Joint by Underwater

Corrosion studies on dissimilar metal joint by underwater welding are carried out in seawater by wire beam electrode method (WBE). Current and potential distributions show that the weld material and heat affected zone (HAZ) are cathodes and the base metal (BM) is anode during the first immersion. After a period of immersion in seawater, anodic current appears in the HAZ. The anodic current maintains till the end of the test. This result demonstrates that corrosion attack occurs predominantly at the HAZ after a long term immersion in seawater. The mechanism is discussed and IR drop in the rust is believed to be one of the main reasons.