Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-53687 Zeitschriftenartikel Fu, B.; Shen, J.; Suhuddin, U.; Pereira, A.; Maawad, E.; dos Santos, J.; Klusemann, B.; Rethmeier, Michael Revealing joining mechanism in refill friction stir spot welding of AZ31 magnesium alloy to galvanized DP600 steel 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. Elsevier Ltd. 2021 Materials & Design 209 109997 urn:nbn:de:kobv:b43-536878 10.1016/j.matdes.2021.109997 https://creativecommons.org/licenses/by/4.0/deed.de 2021-11-03 OPUS4-53688 Zeitschriftenartikel Fu, B.; Shen, J.; Suhuddin, U.; Chen, T.; dos Santos, J.; Klusemann, B.; Rethmeier, Michael Improved mechanical properties of cast Mg alloy welds via texture weakening by differential rotation refill friction stir spot welding Cast magnesium alloys welds produced by refill friction stir spot welding (refill FSSW) show low lap shear strength (LSS) and constantly fail in stirred zone (SZ) shear mode. The cause is most probably related to the heavily textured microstructure. Here, to re-engineer the resulting microstructure, we pro- pose a novel process variant, the differential rotation refill FSSW (DR-refill FSSW). DR-refill FSSW stim- ulates discontinuous dynamic recrystallization and produces a bimodal microstructure with weakened texture. Therefore, the deformation incompatibility between SZ and thermal-mechanically affected zone is avoided. The welds have 50% higher LSS than that of standard refill FSSW welds, and fail in a different failure mode, i.e., SZ pull-out mode. DR-refill FSSW provides a new and effective strategy for improving the performance of spot welds based on microstructural engineering. Elsevier Ltd. 2021 Scripta Materialia 203 114113 urn:nbn:de:kobv:b43-536885 10.1016/j.scriptamat.2021.114113 https://creativecommons.org/licenses/by/4.0/deed.de 2021-11-03 OPUS4-43234 Beitrag zu einem Tagungsband Fu, B.; Shen, J.; Suhuddin, U.; Su, H.; dos Santos, J.; Rethmeier, Michael Microstructure and mechanical properties of a modified refill friction stir spot welds of AM50 magnesium alloy Magnesium (Mg) alloys have attracted much attention due to their merits of meeting requirements of lightweight, energy-efficient and environmental friendly engineering. In this study, a modified refill friction stir spot welding (refill-FSSW) method is proposed to weid AMSO Mg alloy, in which pin and sleeve rotate at different states. Effects of process parameters on the microstructure, material flow, and mechanical properties of welds were studied. Results showed that, the modified refill-FSSW technology could enhance the intennixing of material by changing the flow state. Lap shear strength of welds could be significantly improved with changed failure modes. The modified refill FSSW technology is a competitive welding method for Mg alloy. 2017 WSE & CAWE 2017 7th International Conference on Welding Science and Engineering in conjunction with 3rd International Symposium on Computer-Aided Welding Engineering Jinan, China 18.10.2017 20.10.2017 203 206 2017-12-04