Three-Dimensional Evaluation of Free Surface Roughening Topography of Aluminum Sheet during Various Plastic Strain Paths

The roughening topography on the free surface of polycrystalline metal has important information for understanding the microscopic inhomogeneous deformation as well as the tribological behavior during metal forming processes. In the present study, three-dimensional surface roughening topographies of aluminum sheet in the deformation patterns with different strain ratios are investigated. The deformation with different strain ratio is achieved in the stretch forming test by using the specimens of different shapes. The three-dimensional filtering operation is applied to the measured topography, in order to distinguish the waviness and the roughness. By the newly introduced evaluation technique of the inplane anisotropy of the roughened shape, the differences in the characteristics of surface topography in various plastic deformations are well characterized. The influence of macroscopic deformation pattern on the roughening topography is also discussed concerning the deformation of respective grains.