Post-Overload Fatigue Crack Recovery in Powder Metal Aluminum-Lithium AL-905XL Forging
Technical rept. Aug 89-Sep 90,
DAYTON UNIV OH RESEARCH INST
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An overload fatigue investigation was conducted to determine whether variation in the relative humidity would effect the post-overload retardation recovery period of a dispersion hardened powder metal aluminum, alloy AL905XL forging. Constant amplitude and single spike overload tests were conducted in laboratory air, and in low and high humidity air environments. Post-overload crack opening load and crack propagation velocity were observed to determine the number of delay cycles required for the velocity and crack opening load to return to the values immediately preceding overload. Crack retardation increased in the high humidity environment and for shorter crack lengths attributable to increased crack closure.
- Metallurgy and Metallography