Comparison of Modified Johnson-Cook Model and Strain-Compensated Arrhenius Constitutive Model for 5CrNiMoV Steel during Compression around Austenitic Temperature

Isothermal compression behaviors of 5CrNiMoV steel were studied at temperatures of 870, 800, 750, and 700 degrees C, with strain rates of 0.001, 0.005, 0.01, 0.05, and 0.1 s(-1), the compression temperatures 870 and 800 degrees C are above Ac3, as well as 750 and 700 degrees C below Ac3 temperature. The Modified Johnson-Cook (MJC) model and the Strain-Compensated Arrhenius (SCA) model were employed to demonstrate the relationship between the flow stress and the compression parameters. The correlation coefficient (R) and average absolute relative error (AARE) between the calculational and experimental flow stress were used to evaluate the accuracy of the two models. The results show that the effect of dynamic softening on flow stress is much more significant at higher temperatures and lower strain rates, while this effect is not obvious when the strain rate exceeds 0.005 s(-1) with the temperature below Ac3. The MJC model has a good accuracy close to the reference conditions (0.001 s(-1) and 700 degrees C), and it is suitable to predict the plastic behavior when the flow stress is lower than 200 Mpa. The unbiased AARE values were 6.82 and 5.71 for MJC model and SCA model, respectively, which implied the SCA model has a higher accuracy than the MJC model. The SCA model was believed to be capable of being used to illustrate the thermomechanical behavior of 5CrNiMoV tool steel in a wide range of plastic deformation conditions.