Analysis of surface roughening with uniaxial tension of polycrystalline aluminum by autocorrelation function

The microscopic plastic deformation and the surface roughening behavior of free surface of polycrystalline aluminum sheet during uniaxial tension were experimentally investigated. The free surface roughness profiles are measured during plastic deformation with a confocal laser-scanning microscope. The surface roughness curve was analyzed employing the autocorrelation function and simplified model of surface roughness curve. It is shown that the average inclination of the surface profile curve increases lineally with increasing applied strain, and the grain rotation out of the surface plane is dominant contributor to the surface roughness. The roughness in grains are less than 30% and the roughness of slip bands are less than 7%, respectively, of the total surface profile roughness. The wavelength of the surface roughness curve is about 5 - 9 times the averaged grain size, which increases with the applied tensile strain. Discussions are made on the autocorrelation length, the wavelength of surface profile and the grain boundary position on the surface profile.