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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. [ABSTRACT FROM AUTHOR]

Dynamic precipitation and recrystallization behavior during middle-temperature and appropriate strain rates provide a chance to obtain desirable structure, which significantly improve the mechanical properties of aluminum alloys. In this paper, the microstructure evolution in the typical regions of processing map of 2195 Al-Cu-Li alloy during hot compression was observed via comparative characterization. The effects of dynamic precipitation and particle stimulated nucleation (PSN) on dynamic recrystallization have been analyzed systematically. At lower temperatures and higher strain rates, microshear band leads to a low power dissipation and provides preferential nucleation sites for T 1 precipitates. With temperature increases (<500 °C) and strain rate decreases, the T 1 precipitate bands are formed gradually due to the regular nucleation process on the microshear bands, which therefore limits the further growth of subgrains. Fine recrystallized grains along the grain boundary can also be obtained at high temperature via PSN stimulated by adequate stored energy, which was provided by large deformation near coarse secondary phases. Comprehensive continuous dynamic recrystallization (CDRX) is more prone to occur with the decrease of strain rate, leading to a higher power dissipation at 500 °C / 0.01 s−1. • The relationship between microstructure evolution and hot processing map of 2195 Al-Cu-Li alloy have been investigated. • The formation of T 1 precipitate bands was described, and its influence on dynamic recrystallization has been discussed. • The dynamic recrystallization behaviour around grain boundaries has been discussed. [ABSTRACT FROM AUTHOR]