On performance testing of gasturbine nozzle blades in a corrosive medium

Performance of the nozzle blades GTU manufactured from EhI 868 (KhN60V) heat resistant material having a relatively low yield strength level has been investigated in a complex program under sea salt gas flow conditions. The high temperature fatigue testing in the sea salt gas flow environment has been made at dfferent minimum exit edge temperatures, i.e., 500 deg C, 600 deg C, and 700 deg C. The tests of a number of superalloys reveals that high temperature fatigue strength is enhanced by aluminizing. The testing of blades has been continued following the formation of high temperature fatigue cracks in order to study crack growth kinetics. The entrance and exit edge material has been studied by metallographic techniques. The cracks in the exit edge having tsub(max) = 1050 deg C are found to develop along grain boundaries. In the entrance edge having tsub(max) 985 deg C, the cracks propagate in complicated mode with the intergranular mechanism being predominant