Failure of a Cast Aluminum Engine Head in a High Performance Application
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The investigation described in this article examined a cast aluminum head used in a high performance (drag racing) application. These engine heads had been failing within a few seconds of startup. A sample head was examined to determine the cause. Visual inspection found two cracks on the exhaust side of the head. One crack initiated at the bottom of a spark plug well. The head was then sectioned for metallographic examination and fracture analysis. Metallographic examination revealed a large number of shrinkage pores throughout the casting. The fracture surface intersected many of these shrinkage pores. A significantly sized pore was located near the bottom of the suspect spark plug well near a stress-concentrating feature. This pore acted as the crack-initiating defect, which caused the engine head to fail.
KeywordsCasting Racing Automotive Porosity Shrinkage
- 1.Kaufman, J.G., Rooy, E.L.: The effects of microstructure on properties. In: Aluminum Alloy Castings: Properties, Processing, and Applications, pp. 41–44. American Foundry Society (2005)Google Scholar
- 2.Moreira, M.R., Fuoco, R.: Characteristics of fatigue in Al–Si cast components. Transactions of the American Foundry Society, vol. 114, paper no. 06-122 (2006)Google Scholar
- 3.Interpretation of scanning-electron-microscope fractographs. In: Boyer, H.E. (ed.) Metals Handbook, vol. 9, 8th edn., pp. 64–78. ASM International (1974)Google Scholar