A new mathematical model for predicting flow stress up to the critical strain during hot deformation

• Hot deformation behavior of HDX70 was investigated.
• A new model for predicting flow stress up to critical strain was constructed.
• A new material parameter L was proposed which shows higher accuracy.
• The model for predicting flow stress up to critical strain exhibits better accuracy.

By considering the linear relationship between work-hardening rate and stress, a new mathematical model was proposed for predicting flow stress up to the critical strain during hot deformation. This model is expressed in terms of critical strain, critical stress, and saturation stress. The model shows the critical strain and thus considers the initiation of dynamic recrystallization (DRX). A new material parameter L, resulting in the model’s higher accuracy compared with that of the previous studies. Compared with the measured values, the predicted values show better accuracy, whereas the model of flow stress up to the peak shows lower levels of accuracy. Therefore, compared with the previous model, the mathematical model for predicting flow stress up to the critical strain presents better precision and better reflects the internal mechanism of the changes in the material microstructure.