Comparison of plasticity models for tantalum and a modification of the PTW model for wide ranges of strain, strain rate, and temperature

Four well-known constitutive models for plastic deformation of materials, i.e., Johnson-Cook (JC), Zerilli-Armstrong (ZA), Voyiadjis and Abed (VA), and Preston-Tonks-Wallace (PTW), have been compared with reference to existing deformation data of tantalum in wide ranges of strain, strain rate, and temperature. All of these models reasonably describe the flow stress and the strain-hardening behavior only in the certain ranges of strain, strain rate, and temperature for which the models were developed. The PTW model with appropriate parameters most effectively describes the effects of strain rate and temperature in a wider range, except for strain hardening. The strain-hardening term of PTW was thus modified in the current work and the modified PTW demonstrated very good prediction for the constitutive behavior of tantalum in wide ranges of strain, strain rate, and temperature. (C) 2008 Elsevier Ltd. All rights reserved.