Crack propagation behavior of die-cast AlSiMgMn alloys with in-situ SEM observation and finite element simulation

Crack propagation of die-cast AlSiMgMn alloys with high strength and ductility was investigated using tensile tests with in-situ scanning electron microscopy (SEM) observation and finite element (FE) simulation. Through 3D X-ray micro computed tomography (mu-CT) inspection and reconstruction of pores in the alloys, the pore-scale simulation of tensile fracture was carried out and the stress distribution around pores during the tensile was calculated. The tensile results showed that pores and Fe-rich intermetallics had important effects on the microcracks and the pores played a decisive role in main crack path. It is found that the pore morphologies and locations had significant influence to stress distribution and microcrack. The pores of lower sphericity were prone to cause multi microcracks and promote crack deflection. The experiment results demonstrated that the aggregation of brittle alpha-Fe intermetallics in the alloys also affected the main crack propagation.