Flow Stress Model of Hot Deformation for CoNiV Medium Entropy Alloy

Hot compression experiments were performed to characterize the high-temperature deformation behavior of CoNiV medium-entropy alloy (MEA). Hot compression tests were carried out using a Gleeble-3500 thermomechanical simulator over strain rates of 0.001 s−1 to 1 s−1 and temperatures ranging between 950 °C and 1100 °C. Based on the experimentally determined hot compression data, three models for predicting the flow stress of CoNiV MEA were established: the Zerilli-Armstrong (Z-A) constitutive model, an artificial neural network (ANN) model, and a gated recurrent unit (GRU) model. This study comprehensively evaluated the prediction accuracy of each model using the coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE). The results show that, compared with the other two models, the Z-A model cannot accurately predict the flow behavior of CoNiV MEA in the studied hot-working regime. The R2 value of the ANN model is 0.98974, while the GRU model exhibits the highest predictive capability, with an R2 value of 0.98981, an MAE of 6.29621, and an RMSE of 13.10832. The proposed model demonstrates superior prediction accuracy compared with other models, enabling high-precision characterization of the high-temperature evolution of the flow stress in the CoNiV MEA. This study provides a theoretical foundation for the design and optimization of hot working parameters for the CoNiV MEA.