Precipitation Behavior of Vanadium in HRB500E Steel

In this study the solid solution and precipitation temperature of vanadium in steels had been experimentally determined,and the thermodynamics and kinetics of vanadium particle precipitation had been studied.For the steel with chemical compositions of 0.25%C-0.05%V-0.011%N,the V（C,N） particle begins precipitate at 1 040 ℃.The precipitation temperature rises with increasing V content,while the combination index x of VC_xN_1-x decreases as the content of N increasing.V particle is rich in nitrogen at high temperature precipitates and rich in carbon at lower temperature precipitates.A model of dislocation nucleation in a spherical grain is presented to explain its nucleation and growth mechanism.Taking the mass transfer of vanadium as a constrain factor,the calculation result indicates that the growth rate of precipitates decreases with higher interfacial vanadium concentration and bigger precipitate size.