Influence of carbon on thermal deformation behaviour and deformation/diffusion mechanism of V-microalloyed steel by physical constitutive analysis

Abstract

Hot compression tests of low carbon (0.055C) and medium carbon (0.37C) V-microalloyed steels were carried out in the temperature of 900∼1100 C° and strain rate of 0.005∼10 s–1. The influence of carbon on thermal deformation behaviour and deformation/diffusion mechanism of V-microalloyed steel was studied by three physical constitutive models based on creep theory. It is found that the increase of carbon content has softening effect at low strain rate, but hardening effect at high strain rate. Different carbon content may lead to changes in deformation/diffusion mechanism of V-microalloyed steel. The deformation mechanism of 0.37C steel is dislocation climb, while other deformation mechanism may appear in 0.055C steel. The diffusion mechanism of 0.055C steel is mainly lattice diffusion, while that of 0.37C steel is a synergistic mechanism of lattice diffusion and grain boundary diffusion. The accuracy analysis of the models is consistent with the inferred results of deformation/diffusion mechanism.