Development of plastic strain heterogeneities on cold-rolled aluminium alloys during in situ shear tests inside an SEM

Abstract
Shear tests inside an SEM were performed to study plastic localisation phenomena on cold rolled aluminium alloys 1200, 3004 and 5182. Strain distribution was obtained by image analysis of micro-grids deposited on the sample surface prior to the tests. Macroscopic shear bands initiate from the samples ends and close to the grips after the load maximum. Their spreading through the whole sample occurs by nucleation and propagation of microscopic shear bands, and depends on the alloy and on the direction of shear. The link between the different scales are discussed, from the dislocation microstructures to the rnacroscopic scale. The global boundary conditions govern the distribution of spatial heterogeneities, but the local hardening behaviour controls the localisation sharpness.