Mesoscopic EBSD analysis and mesomechanical behavior of ridging or roping in AA6XXX alloys

Aluminium alloys for car body manufacturing often show a specific type of band-shaped surface roughening upon stretching, called "ridging" or "roping". Experimental researches as well as modelling attempts have indicated that the evolving surface roughness profiles cannot be understood as being merely caused by banding of individual surface texture components, like cube or Goss. Therefore, it is proposed to study banding on the "mesoscopic" scale of texture banding rather than on the "microscopic" scale of orientation banding. In mechanical terms, such patterning in the texture would lead to patterning in, for instance, the Lankford coefficient (r-value), so that the mechanical response can be calculated on an intermediate length scale. The present contribution presents a method for calculating r-value patterning from Electron Backscatter diffraction (EBSD) orientation maps. In a first test case of a strongly ridging AA6xxx sheet, indeed patterning in the r-value is found which corresponds to reported patterning of the surface roughness