High Strain Rate Superplastic Properties of 7075 Aluminum via Friction Stir Processing


Friction stir processing (FSP) leads to fine grained microstructure in commercial 7075 aluminum plates. In this study, the effects of performing multiple, overlapping passes of FSP on 7075 Al were examined. Samples ranging from one to four passes and a nine pass sample were used with a 6.4 mm separation between passes (42% overlap). In the temperature range of 400DGC to 490DGC, the area of overlapping passes exhibited elongations > 200% at a commercially important strain rate of 10-2 s-1. In the nine pass sample, average elongations were greater than 550% at 490DGC at this strain rate. The unprocessed 7075 Al exhibited elongations < 200% similar conditions and hence, no superplastic properties. Strain rate sensitivities of regions in the various passes were found to be -0.5, indicating grain boundary sliding as a dominant mechanism. These results show the potential of using FSP to obtain superplastic properties in commercial aluminum alloys.


Materials Science and Engineering

Keywords and Phrases

Aluminum Base Alloys; Friction Stir Welding; Strain Rate Sensitivity; Superplasticity

Document Type

Article - Conference proceedings

Document Version


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© 2005 The Minerals, Metals & Materials Society (TMS), All rights reserved.

Publication Date

01 Feb 2005

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