Multi-Scale Characterization of Deformation in Aluminum

Materials with deformation behavior sensitive to their microstructure may need deformation analysis at multiple scales to establish the relationship between the microstructure and response to deformation processing. In this work, we use in-plane biaxial test (cruciform) to measure the macro- and microstructure-scale mechanical behavior of a 6061-T6 aluminum alloy at various strain paths. We report flow curves, forming and fracture limits as examples to the macromechanical behavior. As an alternative to the tensile test, it is possible to plot flow curves up to larger strains with the cruciform test. Samples also deform uniformly during the cruciform test and do not develop instabilities in the form of local necks. This allows accurate measurements of forming, and especially fracture limits, under a preset and constant strain ratio. The micromechanical behavior, on the other hand, is quite heterogeneous and microstructure sensitive. Strain localizations at the microstructure scale cause large deviations from the global deformation strains and control the ultimate sample failure at the global scale.