8. Conclusions
1. Visual observations showed that the main reason for the failure in the first-stage-nozzle blade of the gas turbine was hot corrosion. On the basis of the operating temperature of the turbine, which was between 800 to 870 °C, microscopic images, XRD analysis of deposits and EDAX analysis of the blade, the type was HTHC.
2. The results of the FEM analysis showed that the failure factor of the nozzle-blade airfoil trailing edge was thermal stress, which activated the fatigue mechanism. Thus, the ultimate failure of the first-stage-nozzle blade of the gas turbine resulted from the combination of hot corrosion and thermal fatigue