Simulation of the gamma-alpha-transformation using the phase-field method

Phase transformation is a powerful tool to change the properties of steels. Of the known transformations especially the gamma-alpha -transformation is utilised. It occurs in a temperature range relevant for heat treating and hot deformation processes. In this paper an approach is presented in which the gamma-alpha -transformation is simulated with Micress.: This software a pplies the multicomponent multiphase-field model, which is based on the red uction of total free enthalpy. Two different steels have been selected for the simulations, an ULC and an IF steel. Dilatometric tests serve as a basi s for the simulations. These tests have shown that the transformation behav iours of the two steel grades are governed by two different kinetics. The t ransformation kinetics of the IF grade is influenced by the microalloying c oncept applied, resulting in a very slow start of the transformation. This has also been incorporated in the simulations by choosing two different gra in boundary mobilities, one main parameter of the simulation. The simulatio n results of the ULC grade show the huge influence of nucleation undercooli ng as another one of the main parameters. Both simulation results are satis fying. They show that the phase-field method offers a strong simulation too l in the area of phase transformation.