Correlation between the microstructure and corrosion behaviour of copper/316 L stainless-steel dissimilar-metal welded joints

In this study, the correlation between the microstructure and corrosion behaviour of copper/316 L stainless-steel dissimilar-metal welded joints on an electrolytic copper cathode plate was experimentally investigated. Clear phase separation was noted in the weld metal with the γ- and e-Cu phase dominating the Fe-rich and Cu-rich zones, respectively. The difference in the corrosion resistance of these zones means that multiple galvanic corrosion couples are formed in different joint areas. Strong galvanic corrosion between the γ and e-Cu phases caused the shedding of the γ phase particles from the surface, thereby producing corrosion pits and eventually leading to joint failure.