Hot Deformation Behavior and Microstructure Mechanisms of As-Cast 2219 Al Alloy

The hot deformation behavior of ultralarge 2219 Al alloy has been investigated by isothermal deformation tests. The microstructure was characterized by transmission electron microscopy, scanning electron microscopy, and electron backscattered diffraction analysis. The results indicated that the true stress increased rapidly during the initial stage of deformation, then remained stable after reaching the peak stress. The peak stress increased with decreasing temperature and increasing strain rate. It was found that the main restoration mechanisms were dynamic recovery and partial continuous dynamic recrystallization (CDRX). The submicron θ or θ′ particles had a pinning effect on the dislocation motion and grain boundary sliding, and suppressed the CDRX process. In addition, the irregular millimeter- or micron-sized θ particles were broken up during deformation, effectively relaxing the stress concentration and inducing the DRX process.