On deformation and damage micromechanisms in strong work hardening 2198 T3 aluminium alloy

The deformation and damage micromechanisms ahead of a notch in a large flat specimen have been assessed using in situ synchrotron laminography combined with digital volume correlation for the strain evaluation in the material bulk. Despite the enhanced work hardening of the naturally aged Al-Cu-Li alloy several slanted strained bands were found from very early loading onward in the slanted fracture region. The final slanted crack followed one of the strained bands without significant ductile damage growth. In the high stress triaxiality region, close to the notch that underwent substantial local necking, two damage micromechanisms were observed, namely, i) limited void nucleation and growth from intermetallic particles, and ii) slanted shear cracks, even starting from the specimen surface and also located in single grains as shown by post mortem EBSD analyses. In the intermediate region a new deformation mechanism of flip-flopping strain bands and resulting flip-flopping cracks have been revealed using projection DIC measurements. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.