Dynamic recrystallization behaviors of high Mg alloyed Al-Mg alloy during high strain rate rolling deformation

The effects of the rolling parameters (rolling temperature, strain rate and thickness reduction) on the dynamic recrystallization (DRX) behaviors of the direct-chill cast high Mg alloyed Al-Mg alloy (Al-9.2Mg-0.8Mn-0.2Zr-0.15Ti) are carefully investigated. The as-rolled microstructures are characterized by optical microscope (OM), transmission electron microscopy (TEM), electron backscattered diffraction (EBSD) and X-ray diffraction (XRD). Strain rate plays a crucial role in enhancing DRX and the alloy experienced high strain rate rolling (HSRR) at 400 °C with a strain rate of 10 s−1 is featured with a fine-grained microstructure, with the DRX volume fraction of 95.4%, the average grain size of 2.63 μm and the fraction of high-angle grain boundaries (HAGBs) up to 91.9%. The relatively high fraction of HAGBs is associated with the full DRX related to the continuous DRX. The discontinuous DRX and the continuous DRX occur simultaneously in the high Mg alloyed Al-Mg alloy during HSRR and the strain-induced deformation bands (DBs) plays an important role in enhancing the DRX process.