Fatigue Behavior of Semi-Solid Cast Aluminum: A Critical Review

Aluminum alloys are increasingly used in automotive and aeronautic applications to produce high performance, lightweight parts. Among the reasons for this, is the emergence of high integrity processes (HIP), which widens the field of application for cast aluminum alloys. In fact, metallurgical quality and consistency that characterize components produced by HIP are necessary for critical safety components. In addition to attaining maximum strength, critical safety components need to be ductile and resistant to cyclic loading. According to the North American Die Casting Association, rheocasting is a high integrity process capable of producing parts with fewer defects than conventional casting process. Rheocast components are known to have better mechanical properties than permanent mold castings. Moreover, they can be heat-treated which is impractical in the case of classical die cast components. However, the fatigue behavior of rheocast aluminum alloys has been investigated since about 2000 and few results have been published on this subject. This paper reviews the studies of fatigue behavior of aluminum semi-solid cast components. Published experimental results on high cycle fatigue resistance (S-N diagrams), long crack propagation, crack closure effects and short crack particularities are presented.