Effects of Dynamic Precipitation and Processing Parameters on Dynamic Recrystallization Behavior of 2195 Al-Cu-Li Alloy during Hot Compression

To study the effects of dynamic precipitation and processing parameters on the dynamic recrystallization (DRX) behavior of 2195 Al-Cu-Li alloy, the hot deformation process was investigated comprehensively with the temperature range of 300-500°C and strain rate range of 0.001-10 s^-1. An Arrhenius-type constitutive equation and DRX kinetics model were established based on the corrected stress-strain data to unveil the relationship between processing parameters, flow stress and DRX behavior. The shape of flow curves was associated with the dynamic softening mechanism and the DRX softening fraction gradually increased with the decrease of Zener-Hollomon parameter (Z). Then, the microstructure evolution was further analyzed to elucidate the DRX mechanisms at various Z values. The primary softening mechanism was dynamic recovery (DRV). However, when temperature set between 300 and 400°C, T₁ and cubic phases significantly impeded DRV and promoted the occurrence of discontinuous dynamically recrystallization (DDRX) by a strong pinning effect and considerable driving force. As Z value decreased, the recrystallization mechanism transformed from DDRX into continuous dynamic recrystallization (CDRX) attributed to the higher mobility for dislocations. Due to the reduced stored energy and the hindrance of precipitates, grain boundaries were hard to migrate, making it difficult for DDRX grains to grow continuously.