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Friction Stir Weld Restart+Reweld Repair AllowablesA friction stir weld (FSW) repair method has been developed and successfully implemented on Al 2195 plate material for the Space Shuttle External Fuel Tank (ET). The method includes restarting the friction stir weld in the termination hole of the original weld followed by two reweld passes. Room temperature and cryogenic temperature mechanical properties exceeded minimum FSW design strength and compared well with the development data. Simulated service test results also compared closely to historical data for initial FSW, confirming no change to the critical flaw size or inspection requirements for the repaired weld. Testing of VPPA fusion/FSW intersection weld specimens exhibited acceptable strength and exceeded the minimum design value. Porosity, when present at the intersection was on the root side toe of the fusion weld, the "worst case" being 0.7 inch long. While such porosity may be removed by sanding, this "worst case" porosity condition was tested "as is" and demonstrated that porosity did not negatively affect the strength of the intersection weld. Large, 15-inch "wide panels" FSW repair welds were tested to demonstrate strength and evaluate residual stresses using photo stress analysis. All results exceeded design minimums, and photo stress analysis showed no significant stress gradients due to the presence of the restart and multi-pass FSW repair weld.
Document ID
20080036249
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Clifton, Andrew
(Lockheed Martin Michoud Space Systems New Orleans, LA, United States)
Date Acquired
August 24, 2013
Publication Date
June 23, 2008
Subject Category
Metals And Metallic Materials
Meeting Information
Meeting: 19th Aero mat Conference and Exposition
Location: Austin, TX
Country: United States
Start Date: June 23, 2008
End Date: June 26, 2008
Sponsors: ASM International Foundation
Funding Number(s)
CONTRACT_GRANT: NAS8-00016
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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