Mutual Interaction between Fatigue Crack Initiation/Propagation and Microstructural Features in Cast Aluminum Alloys

Abstract:

The correlation between the microstructure, the mechanical properties and the fatigue life of the common aluminum cast alloy Al-7Si-0.3Mg (A356) was investigated. By variation the solution heat treatment temperatures and times the precipitation strengthening effect in the dendritic aluminum solid solution phase and the spheroidization of the eutectic silicon were modified. The results of fully reversed fatigues tests revealed an increase in the fatigue life of specimens that were heat treated at higher temperatures. This observation was supported by analyzing the fatigue crack propagation behavior using the direct current potential drop technique (DCPD). With (i) increasing heat treatment temperature, i.e., increasing dendritic α-Al strength and (ii) roundness of the eutectic silicon particles the resistance to technical fatigue crack initiation, expressed by the threshold value of the stress intensity range K_th, was shifted to higher values.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 488-493
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.488
• Online since: March 2014
• Authors: Ulrich Krupp*, Alexander Giertler, Stephanie Siegfanz, Wilhelm Michels
• Keywords: Aluminum Cast Alloy, Fatigue Crack Propagation, Short Fatigue Cracks, Threshold

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