Phase Field Study on the Austenite/Ferrite Transition in Low Carbon Steel

A phase field model for the austenite/ferrite transition, including the elastic effect caused by the volume mismatch between the austenite and the ferrite, has been presented and applied to the nucleation and growth of the ferrite in the austenite with various cooling rates. The ferrite particles nucleated at the triple junctions of the austenite grains initially grow fast along the grain boundaries. After the austenite grain boundaries are completely wetted by the ferrite, the ferrite starts to grow to the inside of the austenite grain. While it suppresses the growth of the ferrite at the early stage, the elastic field due to the austenite-ferrite volume difference enhances the growth of the ferrite particles at the late stage.