"Al-7Si-0.6Mg is one of the most important cast aluminum alloys because of its attractive mechanical properties and high castability. Microstructurally, the alloy consists of primary aluminum dendrites with eutectic Si particles in the interdendritic region. This makes the alloy quasi-brittle in nature which affects the ductility of the alloy to a great extent. In order to improve the ductility, the eutectic Si particles need to be refined which so far has been achieved by chemical and/or thermal modification. Friction stir processing (FSP) on the other hand can achieve the same through plastic deformation, and therefore replace the cast structure with a wrought microstructure. The eutectic Si particles get refined by at least 50 percent and the aspect ratio also gets reduced. As a result, the FSPed alloy shows improved mechanical properties especially in terms of ductility. Moreover, FSP leads to closure of casting porosities. In the present study it has been observed that these microstructural changes get reflected on the improved fatigue performance by the FSPed alloy. The fatigue life enhances by a factor of five as a result of FSP, when tested using a completely reversed cycle of stress. The life enhancement is even higher at higher stress ratio. Further, FSP caused significant grain refinement inside the stir zone. However, the fine-grain microstructure was found to be unstable at elevated temperatures due to abnormal grain growth (AGG) inside the nugget. Current results indicate that the AGG can be controlled by using selective process parameters as well as run configuration"--Abstract, page iv.
Mishra, Rajiv S.
Newkirk, Joseph William
Miller, F. Scott, 1956-
Landers, Robert G.
Materials Science and Engineering
Ph. D. in Metallurgical Engineering
National Science Foundation (U.S.). Industry/University Cooperative Research Centers
Missouri University of Science and Technology
Journal article titles appearing in thesis/dissertation
- Effect of friction stir processing on fatigue behavior of an investment cast Al-7Si-0.6Mg alloy
- Effect of friction stir processing on microstructure and tensile properties of an investment cast Al-7Si-0.6Mg alloy
- Effect of process parameters on abnormal grain growth during friction stir processing of a cast Al alloy
- Effects of stress ration on the fatigue behavior of a friction stir processed cast Al-Si-Mg alloy
xv, 126 pages
© 2009 Saumyadeep Jana, All rights reserved.
Dissertation - Restricted Access
Aluminum alloys -- Microstructure
Aluminum alloys -- Mechanical properties
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Jana, Saumyadeep, "The role of friction stir processing on the microstructure and mechanical properties of a cast aluminum alloy" (2009). Doctoral Dissertations. 82.
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