Mechanism of high velocity electromagnetic deformation of Al–Mg alloy

Abstract

Electromagnetic ring expansion experiments, as a one-dimensional simplification of the electromagnetic forming process, were performed on AA5083 aluminium alloy at room and cryogenic temperatures. The ductility of the AA5083 alloy is considerably improved at a high strain-rate under electromagnetic loading conditions, compared with that under quasi-static tensile test conditions. The average strain to failure of the specimen obtained at cryogenic temperature is lower than that at room temperature, despite the specimen being expanded at a higher deformation velocity. Characterisation of deformation texture and microstructure evolution was carried out using electron backscatter diffraction and transmission electron microscopy techniques. The results indicate that the significant enhancement in ductility of AA5083 during the electromagnetic ring expansion test at room temperature is a consequence of dynamic recovery, due to the temperature rise in the metal ring caused by the eddy current heat, in addition to an inertial effect at high strain rates.