The evolution of microstructure and texture of AZ80 Mg alloy cup-shaped pieces processed by rotating backward extrusion

This study proposed an effective plastic deformation technique, rotating backward extrusion (RBE), for producing high performance AZ80 magnesium alloy cup-shaped pieces. The RBE process was carried on the Gleeble-3500 test machine at 653 K, and the conventional backward extrusion (CBE) was also conducted for comparison. A detailed microstructure analysis was performed using the optical microscopy (OM) and electron back-scatter diffraction (EBSD). The results shown that the equivalent strain and deformation uniformity of the cup pieces could be substantially increased by the RBE process compared with the CBE process. Furthermore, the RBE process could significantly improve the grain refining capacity and the proportion of dynamic recrystallization (DRX), of which the maximum reduction of grain size was 88.60%, and the maximum increase of DRX proportion was 55.30% in the cup bottom. The main deformation mechanism of the RBE process was the discontinuous DRX (DDRX), while the continuous DRX (CDRX) was also occurred in the cup transition. Compared with the CBE sample, the texture of the cup bottom was weakened for the RBE sample. The microhardness value of the RBE sample was higher than that of the CBE sample, which can be attributed to the grain refinement strengthening.