Corrosion behavior of aluminum/steel dissimilar metals friction stir welding joint

The corrosion performance of aluminum/steel contact and aluminum/steel FSW joint in 3.5 wt.% NaCl solution were analyzed using potentiostatic tests. The post-corrosion microstructure of the welding joint was characterized by optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the localized corrosion of FSW joint of Al/steel dissimilar metals mainly initiated at the interface transition zone (ITZ). Precipitation of intermetallic compounds (IMCs) and Fe-rich phase particles in ITZ accelerated the corrosion of the FSW joint. This phenomenon has been attributed to distinct corrosion potentials between IMCs and steel, aluminum base metal. The corrosion resistance sequence of IMCs in ITZ is Fe₃Al > FeAl > Fe₂Al₅.