A design-centered approach in developing Al-Si-based light-weight alloys with enhanced fatigue life and strength |
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Authors: | Jinghong Fan and Su Hao |
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Affiliation: | (1) Materials Mechanics Research Center, ChongQing University, Chongqing, 400044, China;(2) School of Engineering, Alfred University, Alfred, NY 14802, USA;(3) Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA |
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Abstract: | Material heterogeneities and discontinuities such as porosity, second phase particles, and other defects at meso/micro/nano scales, determine fatigue life, strength, and fracture behavior of aluminum castings. In order to achieve better performance of these alloys, a design-centered computer-aided renovative approach is proposed. Here, the term “design-centered” is used to distinguish the new approach from the traditional trial-and-error design approach by formulating a clear objective, offering a scientific foundation, and developing a computer-aided effective tool for the alloy development. A criterion for tailoring “child” microstructure, obtained by “parent” microstructure through statistical correlation, is proposed for the fatigue design at the initial stage. A dislocations pileup model has been developed. This dislocation model, combined with an optimization analysis, provides an analytical-based solution on a small scale for silicon particles and dendrite cells to enhance both fatigue performance and strength for pore-controlled castings. It can also be used to further tailor microstructures. In addition, a conceptual damage sensitivity map for fatigue life design is proposed. In this map there are critical pore sizes, above which fatigue life is controlled by pores; otherwise it is controlled by other mechanisms such as silicon particles and dendrite cells. In the latter case, the proposed criteria and the dislocation model are the foundations of a guideline in the design-centered approach to maximize both the fatigue life and strength of Al-Si-based light-weight alloy. |
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Keywords: | damage sensitivity map dislocations pileup fatigue microstructure optimization criteria strength |
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