Analyses of P-S-N Curve and Fracture Morphology of Die-Casting Magnesium Alloy AZ91D Containing Mischmetal

Abstract:

The p-S-N curve (p = 50%) of die casting magnesium alloy AZ91D with 1% mischmetal was determined and the fatigue strength corresponding to 3.8 × 10⁵ cycles with 50% probability was 70 MPa. The fatigue fracture surfaces were observed using scanning electron microscopy. The fatigue factures varied with the applied stress and their own defects. The fracture surfaces of some samples loaded lower stress exhibited rubbing mark. The fatigue fracture surface of samples with minor defect possessed the mixed characteristics of quasi-cleavage, tearing ridge, dimple and fatigue striation. Fatigue cracks initiated at gas pores and shrinkage porosity clusters. It were found there was an minor defect size as the site of damage incubation on fracture surface of die casting testing bars which fatigue life was near to the upper bound of fatigue lives.

• Periodical: Applied Mechanics and Materials (Volume 467)
• Pages: 103-107
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.467.103
• Online since: December 2013
• Authors: Yu Lei Xu*, Kui Zhang, Li Han, Ming Feng Li
• Keywords: Die Casting Magnesium Alloy, Fracture, High Cycle Fatigue (HCF), P-S-N Curve

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