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Effects of High Temperature Exposures on Fatigue Life of Disk SuperalloysThe effects on fatigue life of high temperature exposures simulating service conditions were considered for two disk superalloys. Powder metallurgy processed, supersolvus heat treated Udimet (trademark) 720 and ME3 fatigue specimens were exposed in air at temperatures of 650 to 704 C, for times of 100 h to over 1000 h. They were then tested using conventional fatigue tests at 650 and 704 C, to determine the effects of exposure on fatigue resistance. Cyclic dwell verification tests were also performed to contrast the effects of intermixed exposures and fatigue cycles. The prior exposures reduced life by up to 70% and increased the scatter in life, compared to unexposed levels. Cyclic dwell tests reduced lives even more. Fractographic evaluations indicated the failure mode was shifted by the exposures and cyclic dwells from predominantly internal to often surface crack initiations. The increased scatter in life was related to the competition between internal crack initiations at inclusions or large grains producing longer lives, and surface crack initiations at an environmentally affected surface layer producing shorter lives.
Document ID
20040112034
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Gabb, Tim P. (NASA Glenn Research Center Cleveland, OH, United States)
Telesman, Jack (NASA Glenn Research Center Cleveland, OH, United States)
Kantzos, Pete T. (Ohio Aerospace Inst. Cleveland, OH, United States)
Smith, James W. (QSS Group, Inc. Brook Park, OH, United States)
Browning, Paul F. (Solar Turbines International San Diego, CA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2004
Subject Category
Metals And Metallic Materials
Meeting Information
Meeting: International Symposium on Superalloys
Location: Seven Springs, PA
Country: United States
Start Date: September 19, 2004
End Date: September 23, 2004
Funding Number(s)
OTHER: 728-30-09
Distribution Limits
Public
Copyright
Public Use Permitted.

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