Cellular Automata Modeling of Plastic Deformation in Ferrite During Martensite Formation in Dual-Phase Steels

Abstract

The mechanical properties of ferrite-martensite dual phase (DP) steels are influenced by the internal stresses induced during austenite to martensite transformation. The volumetric expansion during this transformation causes plastic deformation of surrounding ferrite grains and creates regions with higher density of geometrically necessary dislocations (GNDs) near ferrite/martensite interfaces. These highly stressed regions can be modelled using the ‘core and mantle’ approach as a thin layer of hardened ferrite present at ferrite/martensite interfaces. The interface layer properties, i.e., its strength and thickness, depend upon surrounding local microstructural features. In the present work, this layer is modelled using cellular automata (CA) based microstructural evolution simulations, which make it possible to track variations in local microstructural features and assign layer properties accordingly. This new approach enables the computational study of the effect of transformation induced stresses on mechanical behaviour of different, fully controlled DP steel microstructures obtained through CA simulations.