Modeling of dynamic recrystallization volume fraction evolution for AlCu4SiMg alloy and its application in FEM

To improve the understanding of coupling effect between dynamic recrystallization (DRX) behaviors and flow behaviors of as-cast AlCu4SiMg, a finite element (FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble-3500 thermo-mechanical simulator in a temperature range of 648-748 K and a strain rate range of 0.01-10(s-1). According to the measured true stress-strain data, the strain hardening rate curves (d sigma/d epsilon versus sigma) were plotted to identify the critical strains for DRX initiation (epsilon(c)). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX (epsilon(0.5)) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.