This research characterizes deformation-induced surface roughness produced by 3, in plane, proportional strain modes to determine the microstructural conditions that promote strain localization in AA5754-O aluminum alloy sheet. Integrating high-resolution scanning laser confocal microscopy and 3-dimensional, matrix-based statistical analysis methods yielded exceptionally accurate and reliable characterizations of the deformed surface structure. Two distinctly different but complementary analyses were performed. The first examined the characteristics present in the raw surface data at different strain levels in the 3 strain modes. The second extended a profile-based surface roughness parameter (Rt) to matrix form to evaluate the propensity for strain localization. The results revealed that 1) the surface structure was sensitive to strain condition, 2) the general composition of the deformation varied with strain condition, 3) the variations were due to dissimilarities in the deformation at the grain level in the individual strain modes, and to inhomogeneities resulting from the PLC effect, and 4) the strain localization data could be well characterized with a 2-parameter Weibull distribution. This study demonstrates that an accurate probabilistic expression that captures all of the subtleties produced by microstructural effects can be developed from raw surface data and used to predict the onset of strain localization.
Citation: Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science
Pub Type: Journals
Strain localization, Strain mode, Scanning laser confocal microscopy, 3-D characterization, Weibull statistics, Metal forming