Correlation of in situ DIC with EBSD for damage investigation in a three-point bending test of an AA6xxx

AA6xxx alloys are widely utilized in automotive applications due to their excellent formability and mechanical properties. However, during bending processes, material failure can occur in the form of cracks, the development of which is strongly influenced by the microstructural fea-tures and the strain state. EBSD (electron backscatter diffraction) and in situ DIC (digital image correlation) measurements were performed on AA6xxx aluminum alloys to investigate the mi-crostructure-related damage during bending. A three-point bending test in a SEM enables DIC analysis, correlating strain maps with EBSD data to identify strain localization and crack initia-tion. Key microstructural features such as pores, precipitates, and shear bands were analyzed for their role in strain localization and failure in the material. Samples were solution heat-treated, rolled to 1 mm thickness, and characterized using EBSD and conventional SEM before in situ bending tests. For nanoscale DIC, the surface was patterned with silica nanoparticles (~ 40 nm), applied via drop casting or polishing. Drop casting provided sufficient particle distribution but caused agglomeration near edges, while polishing yielded more uniform coverage but lower reproducibility. DIC and EBSD data were correlated at the grain scale by aligning strain and crystal orientations using the Python package DefDAP [1] and the MATLAB framework NanoMechAlignment [2], which utilizes the crystallographic toolbox MTEX. Strain maps re-vealed shear bands crossing multiple grains, often coinciding with cracks or pores (Fig 1). High strain localization at grain boundaries and precipitates acted as a precursor to damage-prone areas. This study demonstrated that DIC effectively maps strain localization, with grain bound-aries, precipitates, and shear bands playing key roles in damage initiation in AA6xxx.