Correlation of Surface Roping with Through-Thickness Microtextures in an AA6xxx Sheet

Abstract

Strain-induced surface roughness was quantitatively correlated with microtexture spatial distributions from the surface to the midthickness of a strongly roping AA6016 sheet. The microtexture variations through the sheet were measured by acquiring a series of large area electron backscatter diffraction (EBSD) scans at intervals of about the grain size. The orientations of the different layers were translated into out-of-plane strains using a crystal plasticity model for comparison with the surface roping. The spatial distributions (particularly the characteristic wavelengths) of the microtexture layers were determined by areal auto-correlation functions, and quantitatively compared to the surface appearance by correlation coefficients. The results show that texture banding of Cube/Goss components along the rolling direction is present from the surface to midthickness but with significant variations from one grain layer to another. The wavelength correlation coefficient exhibits a maximum at about 55 μm, or 2 grain thicknesses, below the surface. It is shown that the spatial distribution of Cube/Goss components of the first three or four surface grain layers plays an important role in strong roping of AA6016 sheets.