PSI - Issue 23

I. Bacaicoa et al. / Procedia Structural Integrity 23 (2019) 33–38 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 7. Fracture surface of a specimen with 2.28% Fe failed at 100 MPa and 431,759 load cycles: a) global view of the fracture surface; b) detailed view of the surface

4. Conclusion

The lowest range of the fatigue life probability distribution is characterized by fatigue specimens failing after very few cycles. In the fracture surfaces of these specimens large shrinkage pores interacting with the surface can be observed together with large Fe-rich inclusions joining the dendritic arms of the pores. In this scenario, rapid crack initiation occurs at the surface and crack grows at a high speed as a result of the rupture of the ß -Al 5 FeSi inclusions in the surrounding of the large shrinkage pore. The highest range in the probability distribution (see white spots in Fig. 6.33) is characterized by specimens in which cracks do not initiate from Fe-rich inclusions at the surface. The number of cycles are similar to the cycles in the highest range of the probability distribution from the specimens with 0.6% iron. This implies that high fatigue lives can be achieved in the alloy with 2.28% Fe content provided that the cast skin is free of Fe-rich inclusions that promote rapid crack initiation. Ashtari, P; Tezuka, H., Sato, T. Infuelnce of Sr and Mn Additions on Intermetallic Compound Morphologies in Al-Si-Cu-Fe Cast Alloys. Materials Transactions (2003); Vol. 44; No. 12; pp. 2611-2616. Bacaicoa, I., Luetje, M., Wicke, M., Geisert, A., Fehlbier, M., Brueckner-Foit, A. Characterization of casting defects in Fe-rich Al-Si-Cu Alloys by Microtomography and Finite Element Analysis. Engng. Fract. Mech. (2017), 183, 159-169. Bacaicoa, I., Dwivedi, P.K., Luetje, M., Zeismann, F., Geisert, A., Brueckner-Foit, A., Fehlbier, M. Effect of non-equilibrium heat treatments on the microstructure and tensile prioperties of an Al-Si-Cu alloy. Materials Science and Engineering A (2016), vol. 673, 562-571. Brueckner-Foit, A., Luetje, M., Bacaicoa, I., Geisert, A., Fehlbier, M. On the role of internal defects in the fatigue damage process of a cast Al Si-Cu alloy. Procedia Structural Integrity (2017), vol. 7, pp. 36-43. Das, S.K.,Green, J.A.S. Aluminum industry and climate change-Assessment and responses. JOM (2010), Vol. 62, Issue 2, pp 27-31. EAA/OEARecycling Division. Aluminum Recycling in Europe. European Aluminum (2007), pp. 1-51. Gaustada, G.; Olivetti, E.; Kirchain, R. Improving aluminum recycling: A survey of sorting and impurity removal technologies. Resources, Conservation and Recycling (2012); 58, pp. 79– 87. Kaufman, J.G.; Rooy, E.L. Aluminum alloy castings: properties, processes, and applications. ASM International (2004). Luetje, M., Wicke, M., Bacaicoa, I., Brueckner-Foit, A., Geisert, A., Fehlbier, M. 3D characterization of fatigue damage mechanisms in a cast aluminum alloy using X-ray tomography. International Journal of Fatigue (2017), vol. 103, pp. 363-370. Puncreobutr, C., Phillion, A. B., Fife, J. L., Rockett, P., Horsfield, A. P., Lee, P. D. In situ quantification of the nucleation and growth of Fe-rich intermetallics during Al alloy solidification. Acta Materialia (2014), vol. 79, pp. 292-303. Stein, F., Vogel, S.C., Eumann, M., Palm, M. Determination of the crystal structure of the ɛ -phase in the Fe–al system by high-temperature neutron diffraction. Intermetallics, vol. 18, pp. 150-156. References