On the Capability of Logarithmic-Power Model for Prediction of Hot Deformation Behavior of Alloy 800H at High Strain Rates

Abstract

In this study, the logarithmic-power model has been used to predict hot deformation behavior of alloy 800H at high temperatures. This is for the first time that the logarithmic-power model is examined to model the flow stress curves with negligible flow softening at high strain rates. To this end, flow stress curves of alloy 800H obtained at deformation temperatures from 850°C to 1050°C and at strain rates of 5 and 10 S−1 were employed. The Johnson–Cook model and Shafiei constitutive equation were also used to prove the accuracy of the logarithmic-power model in prediction of flow stress curves of alloy 800H. Evaluation of mean error of flow stress at different deformation conditions showed that the logarithmic-power model can give a more precise estimation of flow stress curves than Johnson–Cook model. Furthermore, it was found out that the accuracy of the Logarithmic-power model and Shafiei constitutive equation was roughly the same in terms of maximum errors obtained in prediction of flow stress curves. Accordingly, it can be concluded that the logarithmic-power model can be employed as a comprehensive model for a wide range of deformation conditions.

Keywords

• high strain rate
• hot deformation
• flow stress
• mathematical modeling
• logarithmic-power model
• alloy 800h