PSI - Issue 23

Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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I. Bacaicoa et al. / Procedia Structural Integrity 23 (2019) 33–38

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Fig. 5 . 3D reconstruction of the shrinkage pores in the specimen failed at 100 MPa and 22 cycles. ß -Al 5 FeSi inclusions located between the dendritic arms of the shrinkage pores located in the fracture surface (orange sub-volume).

Fig. 6 corresponds to the fracture surface of fatigue specimen that failed after 123 cycles at 100 MPa. It is characterized by a large shrinkage pores that reaches extends from the center to the surface of the specimen. Crack initiation is occurs at the point in which the large shrinkage pore reaches the surface and Fe-rich inclusions accelerate the crack propagation along the ß -Al 5 FeSi particles joining the dendritic arms.

Fig. 6. Fracture surface of a specimen failed with 2.28% Fe at 100 MPa and 123 load cycles: a) global view of the fracture surface; b) Large shrinkage pore interacting with the surface.

In Fig. 7 the fracture surface of the specimen with a fatigue life of 431,759 cycles can be observed, in which the area of the cast skin presents a lower density of Fe-rich inclusion. Crack initiation occurred from the surface of the specimen (see Fig. 7b) and it propagated along the hard inclusions of the alloy without reaching any interacting with shrinkage pores.