Effect of Vanadium on Microstructure and Property of Fire- resistant Weathering Steel

In order to investigate the influence of vanadium on the microstructure and properties of fire-resistant weathering steel,the effect of vanadium on CCT diagram,microstructure and tensile properties at both room temperature and high temperature up to 600℃with different kinds of hot-rolling process are researched by dilatometer, electronic microscope,phase analyzing,tensile test and so on.The relationship of the microstructure and property is analyzed.It is found that adding vanadium can raise the temperatures of phase change.The function of vanadium depends on the amount of precipitated phase,which would be finer and denser as the amount of adding vanadium rising,whereas the addition of V increasing from 0.10% to 0.20% promotes the formation of polygonal ferrite.The present of proper bainite fraction in the microstructure is essential for fire-resistant weathering steel in order to obtain enough high-temperature yield strength and high yield strength ratio(YS ratio).