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Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk SuperalloyProtective ductile coatings will be necessary to mitigate oxidation and corrosion attack on superalloy disks exposed to increasing operating temperatures in some turbine engine environments. However, such coatings must be resistant to harmful surface cracking during service. The objective of this study was to investigate how residual stresses evolve in such coatings. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of shot peening and fatigue cycling on average residual stresses and other aspects of the coating were assessed. Shot peening did induce beneficial compressive residual stresses in the coating and substrate. However, these stresses became more tensile in the coating with subsequent heating and contributed to cracking of the coating in long intervals of cycling at 760 C. Substantial compressive residual stresses remained in the substrate adjacent to the coating, sufficient to suppress fatigue cracking. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.
Document ID
20170005889
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Gabb, Timothy P. (NASA Glenn Research Center Cleveland, OH United States)
Rogers, Richard B. (NASA Glenn Research Center Cleveland, OH United States)
Nesbitt, James A. (NASA Glenn Research Center Cleveland, OH United States)
Puleo, Bernadette J. (NASA Glenn Research Center Cleveland, OH United States)
Miller, Robert A. (Vantage Partners, LLC Cleveland, OH, United States)
Telesman, Ignacy (NASA Glenn Research Center Cleveland, OH United States)
Draper, Susan L. (NASA Glenn Research Center Cleveland, OH United States)
Locci, Ivan E. (Toledo Univ. Toledo, OH, United States)
Date Acquired
June 29, 2017
Publication Date
June 1, 2017
Subject Category
Metals And Metallic Materials
Report/Patent Number
GRC-E-DAA-TN42671
NASA/TM-2017-219514
E-19376
Funding Number(s)
WBS: WBS 081876.02.03.04.02.01
CONTRACT_GRANT: NNC12BA01B
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
superalloy
fatigue
corrosion

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