Modeling of subsequent ferrite formation in C-Mn steel after austenite hot deformation

The dislocation density and stored energy of hot deformation were calculated to evaluate quantitatively the effect of hot plastic deformation of austenite on the kinetics of subsequent ferrite transformation. Due to stored energy, the gamma --> alpha equilibrium transformation temperature A(e3) increases to a higher temperature. Under the hot deformation conditions tested, the modeled stored energy is approximately 10-20 J/mol, and the equilibrium temperature A(e3) increases about 10 K, so the practical start transformation temperature moves to higher temperature region. The total driving force DeltaG(gamma-->alpha) of transformation is increased due to the additional stored energy DeltaG(def) too, so the move velocity of the gamma/alpha-interface is quickened. The growth velocity of ferrite increases, which accelerates the transformation progress of ferrite. The equilibrium parameters were calculated by use of super-elements lattice model in continuously cooling. Compared with the results measured in published literature, the modeled transformation dynamics of subsequent ferrite of C-Mn steel after austenite hot deformation agrees well with the measured results.