Development of an In-Situ Observation Procedure for Hot Tear Formation in Aluminum Alloys in Gravity Die Casting

Hot cracks are a widespread defect phenomenon in metal castings. In order to understand the underlying mechanisms and to evaluate numerical models to describe hot crack formation, it is important to know how hot cracks develop during the transition from the liquid to the solid state. An experimental setup is presented, which has been designed to generate hot cracks in aluminum gravity die casting in order to trace their formation during solidification by optical means. The solidification induced shrinkage is correlated with the crack formation. The alloy systems AlSi and AlCu are examined in practically relevant compositions. In addition to the development of the in-situ investigation methodology, the hot cracks produced are examined using elctron microscopy in order to determine the underlying crack mechanisms.