Recycling friendly alloys must tolerate an increased proportion of alloying elements, also those that have previously been avoided due to their tendency to form primary phases, e.g. iron. Despite the increased demand for using scrap in the automotive industry, very good formability of Al-sheets is required, and bendability is of particular interest. Critical points are the intense strain localization and the initiation of surficial roughness, which are followed by macro shear banding and failure due to abrupt cracking in the outer layers. Both factors are influenced by the plastic deformability, which in turn depends on the crystallographic orientations and slip behavior within the grains, and the type, morphology, and distribution of intermetallic phases.

The present study addresses the main factors that allow good bendability, as well as tolerance to applied pre-strain, in different classes of Al alloys. Damage-free bendability has in literature often been correlated to total elongation, yield strength and the presence of certain texture components. We additionally consider the reduction of area and hardening rates during plastic deformation from tensile tests and morphological parameters of the microstructure and the present phases. Also, the damage tolerance of the primary phases, the distribution of local deformation, critical strain localizations and shear bands in the Al matrix that precede crack formation are analyzed by light optical and electron microscopy as well as electron backscatter diffraction to analyze the accommodation of deformation within the different alloy types.