Modeling of Deformation of FCC Polycrystalline Aggregates Using a Dislocation-based Crystal Plasticity Model

Abstract

During thermo‐mechanical processing, dynamic and thermal recrystallization processes occur in materials with low stacking fault energy. Here, climb and cross slip of dislocations are hindered, which generally inhibits recovery processes and promotes recrystallization. As recrystallization processes depend on the nature of the deformed state, to accurately model recrystallisation requires that the microstructural heterogeneities which develop within grains just before recrystallization takes place be accounted for. They typically consist of complex dislocations structures such as dislocation cells, shear bands, twin bands. The aim of this work is to reproduce these heterogeneities just before the onset of thermal recrystallization by the microstructure evolution using a single crystal constitutive framework. The crystallographic constitutive model used for each grain has been implemented into finite element method using a finite‐strain kinematics framework. It accounts for non‐local effects through the introduction of geometrically necessary dislocations (GND). GNDs are required to accommodate the strain gradients due to the lattice incompatibilities associated with the inhomogeneous plastic deformation between neighboring grains. The model is capable of describing the evolution of pure edge and screw dislocations, which is then used to determine the distribution of the stored internal strain energy and the local crystallographic misorientations within each grain. The constitutive framework is employed to study the deformation of polycrystalline copper aggregates deformed under plane strain compression.