Phase Transformation Behavior of Continuously Cooled Fe–C–V–(Mo) Alloys

In this study, the effect of vanadium microalloying in simplified ternary Fe–(0.074–0.244 wt%) C–(0.25–1.01 wt%)V and quaternary (+0.2 wt% Mo) alloys on transformation temperatures and hardness is presented. For this matter, dilatometric investigations of the continuous cooling transformation behavior were performed and correlated with the obtained microstructure. It is shown that Widmanstätten ferrite was formed at higher cooling rates, followed by an increase in the polygonal ferrite fraction with decreasing cooling rates. Widmanstätten ferrite has been fully replaced by polygonal ferrite at faster cooling rates as C and V contents increase. Mo addition retards the kinetics of austenite‐to‐ferrite transformation and leads to a reduced hardening effect during continuous cooling. The more significant hardening at a ferrite finish temperature of 650°C with rising C and V contents, combined with the nearly suppressive effect on pearlite formation and in‐row precipitates observed in scanning electron microscope, supports the presence of a large volume fraction of vanadium interphase precipitates.