An integrated Johnson–Cook and Zerilli–Armstrong model for material flow behavior of Ti–6Al–4V at high strain rate and elevated temperature

Abstract

The Johnson–Cook (JC) model can give an accurate estimate of the flow stress at the low strain rate and temperature, but fails to predict the flow stress under high strain rate and elevated temperature due to the complex relationship among strain, strain rate and temperature. The Zerilli–Armstrong (ZA) model is capable to provide a higher prediction accuracy of material flow stress, but is unable to describe the material behavior above the limitation temperature (0.6Tm). In this research, an integrated JC–ZA model, which considers the grain size, strain hardening, strain rate hardening, thermal softening and the coupled effects of strain, strain rate and temperature, is proposed. The effects of strain rate and temperature on the flow stress of Ti–6Al–4V are investigated by quasi-static tensile test and dynamic split Hopkinson pressure bar test. It is proved that the integrated JC–ZA model has a similar accuracy with JC model at low strain rate and temperature with a prediction error of 2.180–2.358%, and a higher accuracy at high strain rate and elevated temperature with a prediction error in the range of 0.174–2.358%. Through this research, an accurate model by integrating JC model and ZA model for the flow stress of Ti–6Al–4V is given.