A constitutive model for predicting flow stress of Al18B4O33w/AZ91D composite during hot compression and its validation

The flow stress properties of 25 vol.% aluminum borate whiskers reinforced magnesium composite fabricated by gas pressure infiltration were obtained by hot compression test. According to the experimental results, a modified constitutive model was proposed and applied to description of the relationship between deformation temperature, strain, strain rate and flow stress. Based on the experimental data, the material constants of the model were identified by application of nonlinear regression method. Additionally, the derived constitutive model was embedded in a FEM software, by which the experimental hot compression process was simulated. The results shown the load-stroke values of hot compression calculated by FE simulations are in agreement with the measured results in experiments, which indicate the developed constitutive equation can provide an accurate and sound description of plastic deformation of the composite during hot forming process. (C) 2011 Elsevier B.V. All rights reserved.