Characterization of hot deformation behavior of as-homogenized Al-Cu-Li-Sc-Zr alloy using processing maps

The hot deformation behavior of Al-Cu-Li-Sc-Zr alloy and its microstructure evolution were investigated by isothermal compression tests under various deformation conditions. The tests were carried out in the deformation temperature range between 380 and 500 degrees C and at strain rates between 0.001 and 10 s(-1). The constitutive model based on the hyperbolic-sine equation was established to characterize the dependence of flow stress on strain, strain rate and deformation temperature. Based on the experimental data and dynamic materials model, the processing maps at strain of 0.4 and 0.6 were generated to demonstrate the hot workability of the alloy. The results show that the flow stress decreases with increasing deformation temperature, and increases with increasing strain rate. The main softening mechanism is dynamic recovery at 440 degrees C/0.1 s(-1); the dynamic recrystallization of the alloy can be easily observed at 470 degrees C/0.001 s(-1), with peak efficiency of power dissipation of around 57%. With increasing deformation temperature, the volume fraction of dynamic recrystallization increases. At strains of 0.4 and 0.6, the flow instability domain is found at higher strain rates (> 0.3 s(-1)), which mainly locates at the upper part of processing maps. On the basis of processing maps and microstructure evolution, the optimum hot working parameters are in deformation temperature range from 460 to 500 degrees C and at strain rate range from 0.001 to 0.1 s(-1) higher power efficiency of around 42-60%. (C) 2014 Elsevier B.V. All rights reserved.