Onset of fracture in high pressure die casting aluminum alloys

This paper deals with the development of a phenomenological criterion for the prediction of crack initiation in engineering structures made of the pressure die casting alloy Al–10Si–Mg–Mn. A custom-made biaxial testing device is employed to load a newly-designed flat specimen under various combinations of shear and normal loading. In a hybrid experimental–numerical approach, the crack initiation could be studied for stress triaxialities ranging from about 0.0 to 0.6. A phenomenological fracture criterion has been calibrated which predicts the onset of fracture based on the stress triaxiality and the maximum principal strain. The results from post-mortem metallographic analysis suggest that fracture of Si-particles leads to the macroscopic crack formation at stress triaxialities above 0.25, whereas Al-matrix instability failure along with particle–matrix delamination seems to initiate macroscopic cracks at stress triaxialities around 0.0.