A Comparative Study on Constitutive Modeling for Flow Behavior of Ultra-Supercritical Steel at High Temperature

A comparative study has been carried out on the capability of the modified Johnson-Cook (JC) models and a strain-compensated hyperbolic sine constitutive model to predict the flow behavior for FB2 ultra-supercritical steel. To evaluate the material constants of these constitutive models, a series of hot compression tests were performed from 1173 to 1473 K at strain rates of 0.001-0.1 s(-1). The average absolute relative error and correlation coefficient were used to evaluate the suitability. The peak stress and peak strain were calculated and compared. The newly modified JC model predicted the flow stress better over the entire range of the test temperatures and strain rates. The strain-compensated hyperbolic sine constitutive model has a better accuracy to calculate the peak stress and peak strain. However, the modified JC model can only effectively predict the peak stress. The modified JC model can predict the flow behavior in the work-hardening and -softening stages, and it requires a few material constants and a reduced computational time to evaluate these constants compared with the strain-compensated constitutive models.