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Thermal Exposure Effects on Properties of Al-Li Alloy Plate ProductsAluminum-Lithium (AL-Li) alloys offer significant performance benefits for aerospace structural applications due to their higher specific properties compared with conventional aluminum alloys. For example, the application of an Al-Li alloy to the space shuttle external cryogenic fuel tank contributed to the weight savings that enabled successful deployment of International Space Station components. The composition and heat treatment of this alloy were optimized specifically for strength-toughness considerations for an expendable cryogenic tank. Time dependent properties related to reliability, such as thermal stability, fatigue, and corrosion, will be of significant interest when materials are evaluated for a reusable cryotank structure. As most aerospace structural hardware is weight sensitive, a reusable cryotank will be designed to the limits of the materials mechanical properties. Therefore, this effort was designed to establish the effects of thermal exposure on the mechanical properties and microstructure of one relatively production mature alloy and two developmental alloys C458 and L277. Tensile and fracture toughness behavior was evaluated after exposure to temperatures as high as 3oooF for up to IO00 hrs. Microstructural changes were also evaluated to correlate with the observed data trends. The ambient temperature parent metal data showed an increase in strength and reduction in elongation after exposure at lower temperatures. Strength reached a peak with intermediate temperature exposure followed by a decrease at highest exposure temperature. Characterizing the effect of thermal exposure on the properties of Al-Li alloys is important to defining a service limiting temperature, exposure time, and end-of-life properties.
Document ID
20030063047
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Shah, Sandeep
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Wells, Douglas
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Wagner, John
(NASA Langley Research Center Hampton, VA, United States)
Babel, Henry
(Boeing Co. Huntington Beach, CA, United States)
Date Acquired
August 21, 2013
Publication Date
November 25, 2002
Subject Category
Fluid Mechanics And Thermodynamics
Meeting Information
Meeting: AeroMat 2003
Location: Dayton, OH
Country: United States
Start Date: June 9, 2003
End Date: June 12, 2003
Distribution Limits
Public
Copyright
Other

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