Crack initiation behavior and its estimation for a gas turbine rotor based on the EBSD analysis

Daisuke Kobayashi, Akihiro Ito, Masamichi Miyabe, Yukio Kagiya, Yomei Yoshioka

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Abstract

Gas turbine rotors made of Ni-base superalloys were sometimes found to have cracks at the dovetail of the first and second stage wheel. In order to maintain the reliability of gas turbine rotors over the long term, in addition to the application of countermeasures such as the shot-peening process, it is essential to confirm the characteristics of crack initiation mechanisms and to predict the possibility of new cracking. In this paper, first, the case study of crack initiation concerning a wheel dovetail crack has been carried out. Second, to reveal the characteristics of the crack, comparative evaluation between the actual crack and various mechanical fracture samples were conducted by using a scanning electron microscope (SEM) and the electron back-scatter diffraction (EBSD) method which can analyze crystallographic misorientation. As a result, it was found that even in relatively low temperatures, Inconel® Alloy 706 is subjected to brittle grain boundary oxidation when under constant high stress, i.e. a similar phenomenon to stress accelerated grain boundary oxidation (SAGBO), so called hold-time cracking (HTC).

Original languageEnglish
Title of host publicationASME Turbo Expo 2012
Subtitle of host publicationTurbine Technical Conference and Exposition, GT 2012
Pages71-79
Number of pages9
DOIs
Publication statusPublished - 2012 Dec 1
Externally publishedYes
EventASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012 - Copenhagen, Denmark
Duration: 2012 Jun 112012 Jun 15

Publication series

NameProceedings of the ASME Turbo Expo
Volume5

Other

OtherASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012
Country/TerritoryDenmark
CityCopenhagen
Period12/6/1112/6/15

ASJC Scopus subject areas

  • Engineering(all)

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