Fields–Backofen and a modified Johnson-Cook model for CP-Ti at ambient and intermediate temperature

Abstract:

The flow stress behavior of commercial pure titanium (CP-Ti) was studied by uniaxial tension tests at temperatures ranging from 283SK to 573SK and strain rates from 0.00005-0.005s_-1. The tensile properties of CP-Ti was investigated to determine the quantitative variation of the strain rate sensitivity and the strain hardening by temperature based on Fields–Backofen (FB) model. The results indicates that the strain rate sensitivity of CP-Ti at 283K-423K is not obvious and strain hardening index increases with temperature at 353K-573K. A mathematical model using an updated FB equation based on temperature changing was established to describe the plastic flow stress behavior of CP-Ti. Meanwhile by considering the coupled effects of strain, strain rate and temperature, a modified Johnson-Cook(JC) model was proposed to predict the flow behavior. Compared with the original JC model, the modified JC model shows more agreement with the experimental stress, which validates the accuracy of the modified model describing the plastic flow stress of CP-Ti.

Key words:Commercial pure titanium ; Tensile behavior; Fields–Backofen model; Johnson-Cook model