Study on the microstructure and properties of spray formed 7055-T76 aluminum alloy joints by rotating magnetic field assisted friction stir welding.

This study explores an electrically-magnetically-assisted friction stir welding (EMAFSW) method, conducting butt welding experiments on T76 tempered spray-formed 7055 aluminum alloy. Compared to traditional friction stir welding (FSW) processes, the EMAFSW method maintained basically consistent weld hardness, while tensile strength and elongation increased by 13.1% and 72.3%, respectively. The rotating magnetic field enhanced the mechanical stirring action of the welding tool, reduced the size of precipitates, promoted dislocation pinning, and increased the mobility of dislocations. The stirred zone (SZ) and thermo-mechanically affected zone (TMAZ) of EMAFSW weld joint showed significant grain refinement and increased recrystallization proportion, enhancing the weld joint toughness. The joint's fracture behavior shifted from brittle to ductile fracture. • A new method based on rotating magnetic field assisted FSW is proposed. • The grains in SZ and TMAZ of 4 mm-thick spray-formed 7055-T76 aluminum alloy are obviously refined. • The strength of the welded joint is stable and the toughness is improved under the assistance of the magnetic field. • The rotating magnetic field enhances the dislocation motion and improves the plastic flow of the metal during FSW. • EMAFSW is expected to expand the process window of friction stir welding. [ABSTRACT FROM AUTHOR]