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Title: Influence of coarsened and rafted microstructures on the thermomechanical fatigue of a Ni-base superalloy

The aging of the microstructure of Ni-base superalloys during service is mainly characterized by coarsening and rafting of the γ' precipitates. The influence of these different aged microstructures on thermomechanical fatigue (TMF) under either continuously cycled (CC) and creep-fatigue (CF) was investigated. Three different aged microstructures, generated through accelerated aging and pre-creep treatments, were studied: stress-free coarsened γ', rafted with orientation perpendicular to loading direction (N-raft), and rafted with orientation parallel to loading direction (P-raft). Under most conditions, the aged microstructures were less resistant to TMF than the virgin microstructure; however, there were exceptions. Both stress-free coarsened and N-raft microstructures resulted in a reduction in TMF life under both CC and CF conditions in comparison to the virgin material. P-raft microstructure also resulted in reduction in TMF life under CC conditions; however, an increase in life over that of the virgin material was observed under CF conditions. Finally, these differences are discussed and hypothesized to be related to the interactions of the dislocations in the γ channels with γ' precipitates.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3]
  1. Georgia Inst. of Technology, Atlanta, GA (United States). George W. Woodruff School of Mechanical Engineering
  2. Georgia Inst. of Technology, Atlanta, GA (United States). George W. Woodruff School of Mechanical Engineering; Georgia Inst. of Technology, Atlanta, GA (United States). School of Materials Science and Engineering
  3. Siemens Energy Inc., Orlando, FL (United States)
Publication Date:
Grant/Contract Number:
FC26-05NT42644
Type:
Accepted Manuscript
Journal Name:
International Journal of Fatigue
Additional Journal Information:
Journal Volume: 81; Journal ID: ISSN 0142-1123
Publisher:
Elsevier
Research Org:
Siemens Energy Inc., Orlando, FL (United States); Georgia Inst. of Technology, Atlanta, GA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; thermomechanical fatigue; nickel-base superalloy; strain-life; rafting; aging
OSTI Identifier:
1261314
Alternate Identifier(s):
OSTI ID: 1245239