Notch fracture behaviour of 5754 automotive aluminium alloys

The effects of notch severity and impurity iron content on the fracture behaviour of AA 5754 aluminium sheet alloy were examined, under a state of plane strain tension. This was done by studying the fracture evolution in each case. These alloys do not exhibit the progressive damage accumulation often found in ductile commercial sheet alloys, because of a relatively low second-phase iron intermetallic volume fraction and a propensity for shear localisation at large plastic strains. A change in the notch severity affects the fracture morphology and the damage processes that occur prior to fracture. An increase in notch severity favours the nucleation, growth and linkage of voids to create unstable surface shear bands, especially at high-iron contents. The effects of a change in notch severity on strain to fracture are less evident at a high-iron content as the material has an increased propensity to fail by shear localisation.