Through the test at 900 ℃ and 950 ℃ for 100 cooling/heating cycles on the low-pressure turbine blade of K465 alloy an aeroengine

the crack initiation and propagation of the blade during the thermal fatigue test were investigated

and the microstructure and mechanical properties of the blade after thermal fatigue test were analyzed. The results indicate that the thermal fatigue crack is firstly originated from the process hole of the blade and extends perpendicularly to the axial direction of the blade. The stress concentration on the process hole and shrinkage is the main reason for the thermal fatigue crack initiation. After the cooling/heating cycle test

the dimension of γ′ phase in the dendrite arm is increased

and the edges and corners of cubic γ′ phase become smooth and irregular. Due to the precipitation of accicular secondary phase

the elongation of blade is decreased significantly.