Size Effect Mechanism on Foil Rolling Analyzed by Crystal Plasticity Finite Element Method

A novel computational model is presented for the representation of polycrystalline grain structures and crystal plasticity finite element model are used to investigate size effect due to grain orientation and number of grains through the thickness, in term of activity of slip system, roll force and the scatter involved. It is predicted that increasing the number of grains through the thickness has detrimental effects on mechanical performance. It is clear from the current study that foil thickness significantly influences the deformation heterogeneity which leads to non-uniform distributions of strain and the inhomogeneous slip systems active in the cold rolled samples. It is found that the decrease of roll force and slip systems activities in surface grains are caused by the increasing of free surface grain effect when the thickness is decreased.