Crystal-Plasticity Simulation of the Evolution of the Matt Surface in Pack Rolling of Aluminium Foil

Abstract

Aluminium foil is rolled double-layered during the final rolling pass. When the sheets are later separated, the inside surface is dull and the outside surface is shiny. The matt inner side is characterized by significant surface corrugations which are believed to be a precursor for the initiation of fracture upon a subsequent forming operation. Therefore, understanding of the development of the matt side of Al foil will help to control and, eventually, improve the properties of Al foil. It was the goal of the present study to correlate the development of the matt side with the spatial arrangement of the crystallographic orientations of the foil rolling texture. This approach builds on a recent project to correlate the phenomenon of roping in AA 6xxx alloy sheet for car body applications to the occurrence of band-like clusters of grains with similar crystallographic orientation. Large-scale orientation maps obtained by electron back-scattered diffraction (EBSD) were input into a visco-plastic self-consistent crystal-plasticity model to analyse the strain anisotropy caused by the spatial distribution of the various rolling texture components. The new model is applied to several Al foils with different characteristics of the matt side.