Physically-based constitutive model and dynamic recrystallization behavior of AISI 4330V mod. Alloy steel under hot working conditions

This study was designed to propose a method for more accurately predicting high-temperature flow stress curves that include the dynamic recrystallization (DRX) behavior of ingot-forged AISI 4330V mod. alloy steel. Experimental flow stress curves were obtained through hot compression tests conducted under various temperatures and strain rates. The high-temperature constitutive model was established using the physically-based Estrin–Mecking (EM) model in combination with the Avrami equation. To enhance prediction accuracy, key variables such as characteristic stresses, strains, and material constants used in the model were expressed not only as functions of the Zener–Hollomon parameter (Z), but also as functions of forming temperature and strain rate. Finally, macro- and microstructural analyses were conducted to evaluate internal defects, material flow characteristics, and recrystallized microstructures of the compressed specimens. The results showed that the proposed constitutive model could predict the flow stress behavior with high accuracy, yielding a correlation coefficient (R) of 0.9981 and an average absolute relative error (AARE) of 1.66%.