The assessment of service induced degradation of nickel-base alloy Inconel 738LC of the gas turbine blade airfoil hot section, after 24000 hours of operation at high temperature is presented. The assessment include the blade coating degradation, changes of the gamma prime (γ′) phase (aging and coarsening), carbides and brittle phases precipitation, grain type and size characterization, and evaluation of interface coating/base alloy and cracks. The results of blade hot section (airfoil) microstructural assessment are compared to the cold reference zone (bucket root) to show the degradation degree of the alloy and its lifetime consumed. Finally, conclusions are presented indicating the alloy main microstructure elements which influence of blade behavior and the factors that can be used to determine the grade of material deterioration and lifetime consumed.

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