Hot Deformation Behavior of V–Ti Microalloy Steels

Abstract

Hot deformation behavior of V–Ti microalloyed steel is carried out using Gleeble1500. The results show that the flow stress curve is mainly characterized by work hardening and high‐temperature deformation softening mechanisms. Herein, the combination of strain hardening rate–stress curve and stress–strain–temperature dynamic recrystallization 3D model can be used to determine the temperature and strain corresponding to the beginning and end of dynamic recrystallization. The recrystallization activation energy and hot deformation constitutive equation are calculated by austenite recrystallization kinetic regression. Comparing three constitutive equation models with different fitting accuracies, the hyperbolic sine equation with fitting accuracy of 0.99178 is obtained, and the thermal deformation activation energy is determined to be 286.897 kJ mol−1. It is close to the self‐diffusion activation energy of austenite 281 kJ mol−1, so the rate control mechanism under this deformation condition is the dislocation climbing of diffusion control. The combination of the 3D model of dynamic recrystallization and the constitutive equation can not only obtain the flow stress curve under a certain deformation condition, but also obtain the structure evolution information. The mutual verification of the two makes it possible to study the hot deformation behavior under different deformation conditions more comprehensively.