Microstructural Inclusion Influence on Fatigue of a Cast A356 Aluminum Alloy
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We examine the dependence of fatigue properties on the different size scale microstructural inclusions of a cast A356 aluminum alloy in order to quantify the structure-property relations. Scanning electron microscopy (SEM) analysis was performed on fatigue specimens that included three different dendrite cell sizes (DCSs). Where past studies have focused upon DCSs or pore size effects on fatigue life, this study includes other metrics such as nearest neighbor distance (NND) of inclusions, inclusion distance to the free surface, and inclusion type (porosity or oxides). The present study is necessary to separate the effects of numerous microstructural inclusions that have a confounding effect on the fatigue life. The results clearly showed that the maximum pore size (MPS), NND of gas pores, and DCS all can influence the fatigue life. These conclusions are presumed to be typical of other cast alloys with similar second-phase constituents and inclusions. As such, the inclusion-property relations of this work were employed in a microstructure-based fatigue model operating on the crack incubation and MSC with good results.
KeywordsFatigue Fatigue Life Fatigue Crack Growth Void Volume Fraction Near Neighbor Distance
The authors recognize Richard Osborne and Don Penrod for their encouragement of this study, Gerry Shulke for producing the plates, and Westmoreland Mechanical Testing and Research for testing the specimens. This work has been sponsored by the United States Department of Energy, Sandia National Laboratories, under Contract No. DE-AC04-94AL85000, and the Center for Advanced Vehicular Systems (CAVS) at Mississippi State University.
- 1.R.I. Stephens, H.D. Berns, R.A. Chernenkoff, R.L. Indig, S.K. Koh, D.J. Lingenfelser, M.R. Mitchell, R.A. Testin, and C.C. Wigant: Low Cycle Fatigue of A356-T6 Cast Aluminum Alloy—A Round-Robin Test Program, SAE Technical Publication SP760, SAE, 1988a, vol. 881701, pp. 1–28, www.sae.org.
- 2.R.I. Stephens, B.J. Mahoney, and R.G. Fossman: Low Cycle Fatigue of A356-T6 Cast Aluminum Alloy Wheels, SAE Technical Publication SP760, SAE, 1988b, vol. 881707, pp. 93–102, www.sae.org.
- 10.D.A. Lados and D. Apelian: Mater. Sci. Eng. A, 2001, vol. 385, pp. 200–11.Google Scholar
- 12.J.F. Major: AFS Trans., 1997, vol. 102, pp. 901–06.Google Scholar
- 23.J. Fan, D.L McDowell, M.F. Horstemeyer, and K.A. Gall: Eng. Fract. Mech., 2003, vol. 70 (10), pp. 1281, 1302.Google Scholar