Growth Kinetics of Proeutectoid Ferrite in an Fe-0. 09C-1. 5Mn-0. 2Si Steel

Growth kinetics of proeutectoid ferrite, including grain boundary face nucleated ferrite, grain boundary edge nucleated ferrite allotriomorph and intragranular ferrite idiomorph, were experimentally measured in an Fe-0. 09C-1. 5Mn-0. 2Si steel and compared with theoretical calculation in local equilibrium and paraequilibrium modes. Grain boundary edge nucleated ferrite exhibited larger growth rate than grain boundary face nucleated ferrite and intragranular ferrite idiomorph. Experimental kinetics of proeutectoid ferrite was within the window defined by the local equilibrium and paraequilibrium limits. A transition of growth kinetics from paraequilibrium to local equilibrium was observed in the temperature range of 650–750 °C, which can be explained in terms of solute drag.