Constitutive equation and processing map for hot deformation of SiC particles reinforced metal matrix composites

Flow behavior and microstructures of Al/15% SiCp were investigated by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 440 to 500 °C with strain rates of 0.001-1.0 s ^-1. The high-temperature deformation behaviors of Al/15% SiCp were analyzed based on the true stress-true strain curves. The results show that the softening mechanism at low strain rate (0.001 s ^-1) is dynamic recovery, and at high strain rates (0.01, 0.1, and 1 s ^-1) is dynamic recrystallization (DRX). Based on these experimental data, a set of constitutive equations for Al/15% SiCp are described by the Zener-Hollomon parameter, and the coefficients of equations are found to be functions of strain. The constitutive equations reveal the dependence of flow stress on strains, strain rates, and temperatures. Furthermore, the mean error between the experimental and the calculated flow stress was computed. The result shows that the calculated results from constitutive equations are in good agreement with the experimental results. To demonstrate the potential workability of Al/15% SiCp, the processing map was established. The stable zones and the instability zones in processing map are identified and verified through micrographs. As a result, the optimum strain rates and temperatures for effective hot working of Al/15% SiCp were determined.