Texture development of a modified refill friction stir spot weld of AM50 magnesium alloy
By Banglong Fu (Helmholtz-Zentrum Geesthacht), Junjun Shen (Helmholtz-Zentrum Geesthacht), Uceu F.h.r. Suhuddin (Helmholtz-Zentrum Geesthacht), Jorge F. Dos Santos (Helmholtz-Zentrum Geesthacht), Michael Rethmeier (BAM Federal Institute for Materials Research and Testing)

Magnesium (Mg) alloys have attracted much attention due to their merits of meeting requirements of lightweight, energy-efficient and environmental friendly engineering. Joints produced by the conventional refill friction stir spot welding (refill FSSW) have been in general shown to be insensitive to variations of process parameters. In this study, a modified refill FSSW method is proposed to weld AM50 Mg alloy, in which pin and sleeve rotate at different speeds. Lap shear strength test shows that the modified refill FSSW could increase the strength of the weld, which failed with the different fracture mode compared to the weld obtained by conventional refill FSSW. The comparative study is further conducted between conventional and the modified refill FSSW, the microstructure evolutions during welding process and the lap shear strength test are reported. The modified refill FSSW technology is a competitive welding method for Mg alloy.