Phenomenological Constitutive Modeling of High-Temperature Flow Behavior Incorporating Individual and Coupled Effects of Processing Parameters in Super-austenitic Stainless Steel

A novel constitutive model has been developed for predicting flow responses of super-austenitic stainless steel over a wide range of strains (0.05-0.6), temperatures (1173-1423 K) and strain rates (0.001-1 s⁻¹). Further, the predictability of this new model has been compared with the existing Johnson–Cook (JC) and modified Zerilli–Armstrong (M-ZA) model. The JC model is not befitted for flow prediction as it is found to be exhibiting very high (~ 36%) average absolute error (δ) and low (~ 0.92) correlation coefficient (R). On the contrary, the M-ZA model has demonstrated relatively lower δ (~ 13%) and higher R (~ 0.96) for flow prediction. The incorporation of couplings of processing parameters in M-ZA model has led to exhibit better prediction than JC model. However, the flow analyses of the studied alloy have revealed the additional synergistic influences of strain and strain rate as well as strain, temperature, and strain rate apart from those considered in M-ZA model. Hence, the new phenomenological model has been formulated incorporating all the individual and synergistic effects of processing parameters and a ‘strain-shifting’ parameter. The proposed model predicted the flow behavior of the alloy with much better correlation and generalization than M-ZA model as substantiated by its lower δ (~ 7.9%) and higher R (~ 0.99) of prediction.