Aluminum alloy die casting products are extensively used in the industries of vehicle from the advantage of lightweight, near-net shaping and high productivity rate. However, disadvantages of such die castings are the presence of casting defects and the reduction of fatigue strength properties by the defects. In this study, observation of casting defects by X-ray CT and fatigue tests of ADC12 aluminum alloy die casting under tension-compression axial loading were carried out and the relationships between stress amplitude and fatigue life was derived. The fatigue life of ADC12 was greatly influenced by the situation and the amount of casting defects. However, the presence of casting skin did not affect the fatigue life and the inner large pores were not the source of fatigue crack.
