Influence of friction on roughening of the matt surface in aluminium pack rolling

A model has recently been presented to simulate inhomogeneous deformation of polycrystalline materials. This model was based on a finite element analysis using an isotropic plasticity model for the material with a distribution of strengths to simulate the crystallographic texture. By considering plane-strain compression of monolithic material, the displacements generated at the midplane successfully provided a prediction of the roughness at the interface of pack-rolled aluminium foil. In the current study, the predictions of the model are explored further. First, the influence of the friction coefficient μ at the interface between the sheets is assessed using a plane-strain compression model of two sheets. It is found that roughness does not depend greatly on μ when μ>0.1, being close to that predicted by the monolithic model. However, the roughness does increases significantly as μ falls below 0.1. Secondly, a plane-strain rolling model is used to clarify the effects of friction between the roll and the strip. It is found that neither the friction at the roll surface nor the roll diameter has a strong effect on the roughening of the internal matt surface. It is concluded that the model using plane-strain compression of monolithic material is appropriate to predict the roughness on the matt surface of pack-rolled materials.