A modified Johnson-Cook constitutive model for Mg-Gd-Y alloy extended to a wide range of temperatures

In this paper, a new phenomenological and empirically based constitutive model was proposed to change the temperature term in the original Johnson-Cook constitutive model. The new model can be used to describe or predict the stress-strain relation of the metals deformed over a wide range of temperatures even though the current temperatures were lower than the reference temperature. Based on the impact compression data obtained by split Hopkins pressure bar technique, the material constants in the new model can be experimentally determined using isothermal and adiabatic stress-strain curves at different strain rates and temperatures. Good agreement is obtained between the predicted and the experimental stress-strain curves for a hot-extruded Mg-10Gd-2Y-0.5Zr alloy at both quasi-static and dynamic loadings under a wide range of temperatures ever though the current temperatures were lower than the reference temperature. (C) 2010 Elsevier B.V. All rights reserved.