Abstract

FGH96 is regarded as a promising powder metallurgy superalloy for high-temperature / pressure turbine disc in aerospace industries due to its high resistance / defect tolerance and high working temperature up to 750 °C. The initiation and propagation mechanism of FGH96 PM superalloy is researched by in-situ fatigue experiments. The result shows that the crack of gap samples initiates and propagates at the same stress level at 25 °C and 300°C. At 300°C, there are no creep characteristics such as the intergranular characteristics found in the sample fracture. The crack at 300°C has a faster initiation and propagation process compared to the crack at 25°C, especially in the late stage of fatigue. The increase of the crack propagation rate of the sample is unrelated to the creep, mainly due to oxidation. Oxidation reduces the fatigue life of materials because it accelerates the initiation and propagation of transgranular cracks.

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