@misc{fu_revealing_joining_2021, author={Fu, B.,Shen, J.,Suhuddin, U.,Pereira, A.,Maawad, E.,dos Santos, J.,Klusemann, B.,Rethmeier, M.}, title={Revealing joining mechanism in refill friction stir spot welding of AZ31 magnesium alloy to galvanized DP600 steel}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.matdes.2021.109997}, abstract = {The application of magnesium (Mg) inevitably involves dissimilar welding with steel. A novel solid state spot welding method, refill friction stir spot welding (refill FSSW), was utilized to weld AZ31 Mg alloy to galvanized DP600 steel. Although Mg/Fe is an immiscible alloy system, defect-free welds with high strength were successfully obtained in a wide parameter window. The results of microstructure, interfacial reactions, and mechanical properties are reported to reveal the underlying joining mechanism. Due to the melting of Zn coating and subsequent Mg-Zn reactions, Mg-Zn eutectic and intermetallic compounds were detected within welds. Heterogeneous interfacial reactions occur along Mg/steel interface, and the relationship between interfacial structure and fracture behavior was investigated. The joining mechanism is associated with Zn coating and Fe-Al layer: 1) the presence of Zn coating is beneficial for achieving high-quality welding between Mg and steel, it protects the interface from oxidation and contributes to brazing of the weld; 2) the Al present in Mg alloy reacts with Fe, resulting in the growth of Fe-Al layer, which contributes to the diffusion bonding in the interface. The overall results clearly show that refill FSSW is a competitive welding method for joining Mg and galvanized steel.}, note = {Online available at: \url{https://doi.org/10.1016/j.matdes.2021.109997} (DOI). Fu, B.; Shen, J.; Suhuddin, U.; Pereira, A.; Maawad, E.; dos Santos, J.; Klusemann, B.; Rethmeier, M.: Revealing joining mechanism in refill friction stir spot welding of AZ31 magnesium alloy to galvanized DP600 steel. Materials & Design. 2021. vol. 209, 109997. DOI: 10.1016/j.matdes.2021.109997}}