Ferrite grain refinement in V-microalloyed steels

摘要

The present work has concentrated on the role of V in ferrite grain refinement by promoting intragranular ferrite nucleation. It was shown that V contributes to the formation of two types of intragranulary nucleated ferrite; polygonal ferrite and acicular ferrite. Intragranular polygonal ferrite nucleates on VN particles in the narrow temperature range, between 650-600°C. Acicular ferrite forms in V-steels during isothermal transformation at lower temperatures (～450°). The acicular ferrite microstructure was obtained in V-microalloyed steels containing either high or very low N levels. This suggests that V on its own can promote the formation of the acicular ferrite microstructure.