Physically-Based Constitutive Model and Dynamic Recrystallization Behavior of Aisi 4330v Mod. Alloy Steel Under Hot Working Conditions

Abstract

This study was designed to predict the hot deformation characteristics and dynamic recrystallization behavior of ingot-forged AISI 4330V mod. steel. The high-temperature flow stress curves of this material were obtained through hot compression tests under various temperature and strain rate conditions. The high-temperature constitutive model was established using the physically-based EM model and the Avrami equation. In particular, to improve prediction accuracy, characteristic stress and strain values, material constants, and various parameters used in the constitutive model were expressed not only as functions of the Zener-Hollomon parameter (Z) but also as functions of temperature and strain rate. Finally, the defects, material flows, and recrystallized structures inside the compressed specimens were analyzed through macrostructure observation. The results showed that the proposed constitutive model predicted the flow stress curves with high accuracy under various temperature and strain rate conditions, achieving a correlation coefficient (R) of 0.9981 and an average absolute relative error (AARE) of 1.66%. Even within the same compressed specimen, recrystallized structures were observed in the low-deformation zone (dead metal zone) in contact with the die, whereas in the high-deformation zone, only material flow lines were observed without recrystallized structures. These phenomena became more pronounced with increasing strain rate and temperature.

Keywords: AISI 4330V mod. alloy steel, Dynamic recrystallization behavior, high-temperature constitutive model, flow stress curve