Blade Failure in Second Stage Turbine
The present paper reports the investigation of a sudden blade fracture leading to a fatal engine failure. The blade sample was subjected to a series of examinations, including visual examination and photographic documentation, optical microscopy, scanning electron microscopy (SEM), using both energy dispersive spectroscopy (EDS) and X-ray mapping. Analysis of all elements show that loss of aluminum from coating due to oxidation and coating phases changing; decreasing of alloy ductility and toughness due to carbides precipitation in grain boundaries; degradation of the alloy gamma prime γ' phase (aging and coarsening) and micro cavities. These were found on fracture surfaces which served as an origin of creeping failure mechanism and are the most important factor for failure of this blade.
H.S. Lee, I.S. Yoon and M.H. Aliabadi
K. Mohammadi and A. K. Haghi, "Blade Failure in Second Stage Turbine", Key Engineering Materials, Vols. 385-387, pp. 393-396, 2008