Abstract
A turbine blade has fractured after 74,461 h of exposure to service conditions in a power station. The fracture surface is found to be composed of square and slant sections corresponding to tensile and shear modes, respectively. Most evidence points out that the fracture has been initiated by thermal fatigue in the protective coating at the trailing edge. Continued propagation of the cracks with extended thermal exposure leading to fracture is found to occur intergranularly by creep mechanism aided by formation of denuded zones free of the strengthening γ′-phase alongside the grain boundaries. The microstructural changes leading to the formation of the denuded zones and the role of the coating are elucidated.
| Original language | English |
|---|---|
| Pages (from-to) | 78-90 |
| Number of pages | 13 |
| Journal | Metallography, Microstructure, and Analysis |
| Volume | 4 |
| Issue number | 2 |
| DOIs | |
| State | Published - 1 Apr 2015 |
Bibliographical note
Publisher Copyright:© 2015, Springer Science+Business Media New York and ASM International.
Keywords
- Coatings
- Electron microscopy
- Fracture
- Superalloys
- Turbine blades
ASJC Scopus subject areas
- Metals and Alloys