NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Effectiveness of Shot Peening in Suppressing Fatigue Cracking at Non-Metallic Inclusions in Udimet(trademark) 720The fatigue lives of modern powder metallurgy disk alloys can be reduced by over an order of magnitude by surface cracking at inherent non-metallic inclusions. The objective of this work was to study the effectiveness of shot peening in suppressing LCF crack initiation and growth at surface nonmetallic inclusions. Inclusions were carefully introduced at elevated levels during powder metallurgy processing of the nickel-base disk superalloy Udimet 720. Multiple strain-controlled fatigue tests were then performed on machined specimens at 427 and 650 C in peened and unpeened conditions. Analyses were performed to compare the low cycle fatigue lives and failure initiation sites as a function of inclusion content, shot peening, and fatigue conditions. A large majority of the failures in as-machined specimens with introduced inclusions occurred at cracks initiating from inclusions intersecting the specimen surface. The inclusions could reduce fatigue life by up to 100X. Large inclusions had the greatest effect on life in tests at low strain ranges and high strain ratios. Shot peening can be used to improve life in these conditions by reducing the most severe effects of inclusions.
Document ID
20050161951
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Barrie, Robert L. (Army Research Lab. Cleveland, OH, United States)
Gabb, Timothy P. (NASA Glenn Research Center Cleveland, OH, United States)
Telesman, Jack (NASA Glenn Research Center Cleveland, OH, United States)
Kantzos, Peter T. (Ohio Aerospace Inst. Brook Park, OH, United States)
Prescenzi, Anthony (Ohio State Univ. Columbus, OH, United States)
Biles, Tiffany (Ohio Aerospace Inst. Brook Park, OH, United States)
Bonacuse, Peter J. (Army Research Lab. Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
March 1, 2005
Subject Category
Nonmetallic Materials
Report/Patent Number
E-15044
NASA/TM-2005-213577
Meeting Information
Meeting: 2003 Annual Meeting and Exhibition
Location: San Diego, Ca
Country: United States
Start Date: March 2, 2003
End Date: March 6, 2003
Sponsors: Minerals, Metals and Materials Society
Funding Number(s)
WBS: WBS 22-079-30-09
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available