Fracture Features of FGH97 Powders Superalloy

The fracture features of FGH97 powders superalloy were studied under the conditions of low-cycle fatigue, high-cycle fatigue and stress rupture. The results show that the low-cycle fatigue fracture surfaces had only one source at low strain, and the characteristics at the first stage of fatigue crack expanding was similar cleavage planes. However, at high strain, the low-cycle fatigue fracture surfaces had multi-sources, and the characteristics at the first stage of fatigue crack expanding was fatigue striations. The large range of similar cleavage planes existed at the first stage of fatigue crack expanding on the high-cycle fatigue fracture surfaces, and the characteristics at the second stage of fatigue crack expanding was fatigue striations. The characteristics of stress ruptured zone was transgranular similar cleavage at 500 ℃, and above 500 ℃, the characteristics was one and two way slipping of dislocations activated in the alloy as deformation goes on, some of dislocations congregated at the grains boundary regions to bring the stress concentration which promoted the initiation and propagation of the microcracks, which was thought to be the fracture mechanism of FGH97 powders superalloy during stress rupture.