Microscopic evaluation of creep-fatigue interaction in a nickel-based superalloy

Conference · Thu Jan 01 04:00:00 EST 2009

OSTI ID:1029560

Santella, Michael L ^[1]; Yamamoto, Masato ^[2]; Shingledecker, John P ^[1]; Boehlert, C. J. ^[3]; Ogata, Takashi ^[1]

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1. ORNL
2. CRIEPI, Japan
3. Michigan State University, East Lansing

In order to verify the applicability of Nickel-based alloy Alloy 263 for the thick component, a series of creep, fatigue and creep-fatigue experiments were carried out. To investigate the detailed damage process under the creep-fatigue condition, simple aged, crept, fatigued, and creep-fatigued specimens were subjected to electron back scattering diffraction (EBSD) pattern observation in the SEM. While the simple aged and fatigued specimens showed no remarkable local change in orientation (less than 1deg), the crept specimen exhibited inhomogeneous change of crystallographic orientation, at most 5 degrees, within the grains. This shows that the creep strain is inhomogeneously distributed in the grains due to the effect of relative constraint among the grains. The creep-fatigued specimen exhibited similar local inhomogeniety in strain distribution compared to the crept sample near the center of the grains. However, the creep-fatigued specimen showed remarkable local change in orientation at the vicinity of grain boundaries up to 15 degrees, indicating the occurrence of high strain concentration nearby the grain boundaries. A detailed observation of creep-fatigue damage evolution process in SEM revealed that the inhomogeneous grain deformation precedes the remarkable inhomogeneous deformation nearby the grain boundaries, and followed by the grain boundary cracking.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: FE USDOE - Office of Fossil Energy (FE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1029560
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
CREEP
DEFORMATION
DIFFRACTION
DISTRIBUTION
ELECTRONS
EVALUATION
FATIGUE
GRAIN BOUNDARIES
HEAT RESISTING ALLOYS
NICKEL BASE ALLOYS
ORIENTATION
SCATTERING
STRAINS