Mesoscale simulation of deformed austenite decomposition into ferrite by coupling a cellular automaton method with a crystal plasticity finite element model

Austenite to ferrite transformation during continuous cooling in a C-Mn steel with heterogenously deformed microstructure is simulated by coupling a cellular automaton approach with a crystal plasticity finite element model. The uniaxial hot compression results given at the coordinates of integration points of finite element mesh, namely the local stored energy of deformation and the crystallographic orientation, are simulated based on the crystal plasticity theory. These data are mapped onto a regular lattice in the cellular automaton method as an input of the initial deformed microstructure conditions using an interpolation approach. The local stored energy of deformation is incorporated in the cellular automaton approach as an additional driving force for subsequent ferrite nucleation and growth. Besides ferrite nucleation on austenite grain boundaries, intragranular ferrite nucleation occurs in areas with high local stored energy of deformation within austenite grain interiors. The simulations demonstrate the inhomogeneous microstructure evolution during deformed austenite decomposition because of the deformation concentration at locations such as austenite grain boundaries and austenite grain interiors. The simulated average kinetics of microstructural evolution during deformed austenite decomposition into ferrite in a C-Mn steel is also compared with the experimental results in the literature.