Evaluation of a serviced turbine blade made of GH4033 wrought superalloy

A 2nd stage turbine blade from an aircraft engine, which was made of wrought Ni-based superalloy GH4033, was investigated after service exposure of 1600 engine operating hours with regard to multiple microstructural degradations and the corresponding stress rupture lives. Thermal exposure experiments were also carried out to simulate the microstructural evolution of GH4033 alloy. The gradual change of GB carbide morphology and coarsening of γ′ precipitates were observed after thermal exposures at 650 °C and 700 °C for 100-2000 h, and the corresponding TTP diagram of GB carbides as well as the coarsening kinetic equation of γʹ precipitates were determined. In this study, apparent microstructural degradation in terms of grain growth, GB carbide degradation, coarsening of γʹ precipitates and dislocation substructure as well as obvious reduction of creep life were not identified in the serviced blade after service exposure. The service temperature from the middle to the tip of the airfoil was estimated to be 650-700 °C based on microstructural features of γʹ precipitates and GB carbides.