Influence of anodization on the fatigue life of WE43A-T6 magnesium
- Univ. of Notre Dame, IN (United States). Dept. of Aerospace and Mechanical Engineering
- AlliedSignal Inc., South Bend, IN (United States). Aerospace Equipment Systems
An experimental study was performed to evaluate the influence of the anodic Magoxid-Coat on the fatigue life of WE43A-T6 magnesium. Rotating-bending fatigue tests were performed under ambient lab-air conditions at various stress levels over the cycle range N {approximately} 10{sup 3} to 30 {times} 10{sup 6}. Comparisons between the S-N curves for bare specimens and specimens with three different anodic coating thicknesses were made. The results showed no apparent influence of anodic coating thickness on fatigue strength. A decrease in strength of 11 to 6% was observed for the coated specimens in the long-life regime (N > 10{sup 5} cycles), but no difference was observed in the low cycles regime (N < 10{sup 4}). Microscopic observations of the specimen sides after testing showed that nonfatal fatigue cracks were initiated at applied stress levels above approximately 100 MPa on both the bare and anodized specimens. The difference in fatigue performance between the bare and anodized specimens is considered in terms of the coating`s influence on the cycles to crack initiation and cycles expended in propagating the crack to specimen failure. The initiation cycles are influenced by the pores and inclusions on the anodic coating surface and the barrier layer at the metal-oxide interface. The propagation cycles are influenced by the multiplicity and location of initiation sites, which affect, in turn, crack growth and coalescence during the fatigue fracture process.
- OSTI ID:
- 352447
- Journal Information:
- Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 8 Vol. 40; ISSN 1359-6462; ISSN SCMAF7
- Country of Publication:
- United States
- Language:
- English
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