Influence of Deformation and Molybdenum Content on Acicular Ferrite Formation in Medium Carbon Steels

The present work deals with the influence of deformation and molybdenum content on the subsequent austenite-to-acicular ferrite transformation during continuous cooling in medium carbon microalloyed steels. The results obtained demonstrate that higher deformation temperature induces a finer austenite grain size as a result of austenite recrystallisation processes during cooling down to austenite decomposition temperature. The higher the molybdenum content and severity of deformation are, the finer austenite grain is. Likewise, it was concluded that molybdenum suppress pearlitic microstructure, and clearly delay proeutectoid ferrite field to longer times. By contrast, acicular ferrite transformation is enhanced in molybdenum rich steel, which not only affect the volume fraction but also the morphology of acicular ferrite. © 2006 ISIJ.