Three different heat treatments of aluminum alloy AA5052 were subjected to various levels of uniaxial plastic strain. The resulting surface topographies were then evaluated using scanning laser confocal microscopy (SLCM) and stylus profilometry. Statistical analyses were performed to compare the quality of a linear fit to a curvilinear fit for the roughness data as a function of true plastic strain. Three different regression approaches were used to determine the most appropriate regression model. While there were differences in the SLCM results, the regression analyses revealed that a linear fit was more statistically appropriate for the finest grain size. As the grain size increased, a quadratic fit became more statistically appropriate. This was attributed to the more complex surface morphology in the largest grain size producing a more complex relationship between roughness and plastic strain due to the grain size dependence of the relative area fractions of grain boundary-localized roughness and slip-induced roughness. The differences between the SLCM and profilometry results were attributed to the natural filtering that occurs during contact profilometry. This filtering skewed the roughness data toward the largest surface displacements, thereby reducing the measurement fidelity to where the only possible outcome was the linear relationship.
Citation: Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science
Pub Type: Journals
Surface roughness, Plastic deformation, Aluminum alloy, Scanning laser confocal microscopy (SLCM), Topographic analysis, Sheet metal forming