A modified Zerilli–Armstrong constitutive model to predict hot deformation behavior of 20CrMo alloy steel

• The modified Z–A model predicts the flow stresses accurately.
• Comparing with the J–C model, the computational time of Z–A increases by many folds.
• The modified Z–A model has a relatively higher accuracy than the J–C model.
• The modified Z–A model is more difficult to develop than the J–C model.

True stress and true strain values were obtained from isothermal hot compression tests conducted on a Gleeble thermal simulation machine, in a wide range of temperatures (1173–1373 K) and strain rates (1.5 × 10−3–1.5 × 10−2 s−1). The experimental data were used to develop a modified Zerilli–Armstrong constitutive model. The predicted flow stresses using the developed model were compared with experimental values. A correlation coefficient (R) of 0.989 and an average absolute relative error (AARE) of 7.71% between the measured and calculated flow stresses have been obtained. Comparing with a modified Johnson–Cook model developed in the authors’ previous study, the accuracy, the number of material constants involved and the computational time required of the model were evaluated.