Creep damage evaluation of IN738LC based on the EBSD method by using a notched specimen

Daisuke Kobayashi, Masamichi Miyabe, Yukio Kagiya, Yoshiko Nagumo, Ryuji Sugiura, Takashi Matsuzaki, A. Toshimitsu Yokobori

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The Ni-base superalloy IN738LC developed as a heat-resistant material has excellent high temperature strength, but at the same time it has a brittle property. As a result, any evidence of creep degradation such as deformation of components or initiation of creep voids has hardly made an appearance by the end of its available creep life. This paper investigates the possibility that creep damage can be evaluated by using the electron backscatter diffraction (EBSD) method to analyze misorientation which is considered to be caused by creep strain. The use of an in-situ observational testing machine with a notched specimen allowed creep-EBSD round tests which consisted of creep tests in the in-situ observational testing machine and EBSD observations using scanning electron microscopy (SEM) alternately against an identical specimen. The outcome of these experiments was that crystal orientation change tendencies corresponding to the creep strain were continuously observed. It has been found that there was a good correlation between the creep strains and the misorientations referenced to the average orientation in the grain, the parameter of Grain Reference Orientation Deviation (GROD) defined by TSL EBSD system. Consequently, this study shows that the creep damage could be estimated by analyzing misorientations using the EBSD system automatically. Also, it has been found that crystal orientation changes appeared around notches in the direction of maximum shearing stress, which implies that the misorientation development was caused by the crystallographic lattice rotation.

Original languageEnglish
Pages (from-to)157-167
Number of pages11
JournalStrength, Fracture and Complexity
Volume7
Issue number2
DOIs
Publication statusPublished - 2011 Dec 29

Keywords

  • Creep damage
  • EBSD
  • IN738LC
  • in-situ
  • misorientation
  • observational test

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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