X-ray computed tomography vs. metallography for pore sizing and fatigue of cast Al-alloys

Pores associated to the casting process are highly detrimental to the fatigue behavior of Al–Si alloys. The severity of casting pores in fatigue is related to a number of factors, such as pore size, morphology, position within the cast part, etc.. Metallography is readily applied to statistical pore characterization. However, random 2-D sections through pores do not provide good estimates of the defect size without further data analysis. In this contribution two experimental techniques, namely X-ray computed tomography and metallography, are applied to cast AlSi7Mg to characterize the size and morphology of casting pores. The 3D evidence provided by XCT is used to discuss pore sizing criteria based on metallographic measurements. The stress concentration due to the real 3D pore morphology is then investigated with finite element method and compared to simplified 2D pore models.