The macro-fracture crack defects which appeared in the manufacture process of ZL101 aluminium alloy base casting was analyzed by chemical composition

mechanical properties and tensile fracture with the help of spectrum analysis

optical microscope（OM）

scanning electron microscope（SEM）

energy dispersive spectrometer（EDS）and mechanical property testing.The chemical composition nearby macro fracture crack is in line with HB962-2001 standards

and both the tensile strength under casting and T5 heat treatment state are more than 150MPa with elongation more than 4%.In addition

tensile fracture is characterized by the typical intergranular fracture morphology

where crack is generated in the grain boundry among the primary and eutectic silicon particles

then propagated along the grain boundry rapidly.Silicon particles are gradually spheroidized after T5 heat treatment.The FEM numerical simulation analysis of static force load shows that the peak static loading stress is decreased from 206.9MPa to 91.6MPa

and the dynamic displacement is reduced from 1.39mm to 0.61mm when enhanced rib is reduced from 10mm to 5mm

decreasing the macro-defects and improving the quality of the aluminum alloy base.