Corrosion behavior in aluminum/galvanized steel resistance spot welds and self-piercing riveting joints in salt spray environment

This paper underlined the corrosion behavior of aluminum alloy/galvanized steel joints fabricated by resistance spot welding (RSW) and self-piercing riveting (SPR) exposed to different salt-spray cycles. It was found that crevice generated joining methods has an important impact on behavior. Compared with RSW joint, less happened coupled regions in SPR because higher local pH value resulted from smaller crevice. The crevice, however, types products. Galvanic region for both joints. Pourbaix diagram explained stable products Al ZnFe alloy, which are Al2O3, ZnO, Fe3O4. Additional observed experiment included α-Al(OH)3, Ca4Al2(CO3)(OH)12(H2O)5, Zn5(OH)8Cl2(H2O), Zn5(CO3)2(OH)6, Fe2(OH)2(CO3), can be understood considering metastable products, diagram, possible chemical reactions.