Fatigue life assessment of aluminum alloys with casting defects

Abstract The fatigue lifetimes of cylindrical aluminum specimens containing shrinkage cavities were measured. The results were compared with those of specimens without macroscopic cavities (DC cast). Two different heat treatments were considered: T4 (naturally aged) and T6 (near peak aged). The pore shape and distribution in the specimens were complex. Pores with a maximum diameter larger than 0.2 mm resulted in a significant reduction of the lifetime. Numerical calculations were carried out to predict the fatigue life and crack growth model taking crack closure effects into account was used. This model tended to give somewhat nonconservative results when compared with test results. Modification of the model, taking a short crack effect into account, gave conservative results.

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