Thermal fatigue crack initiation and propagation behaviors of GH3230 nickel-based superalloy

The drastic severe temperature cycle in an aero-engine combustion chamber leads to large thermal fatigue stress, which may induce thermal fatigue failure of the combustion chamber. In this paper, thermal fatigue crack initiation and propagation behaviors of GH3230 nickel-based superalloy sheet specimens with V-notch were studied under different peak temperatures 800 degrees C, 900 degrees C, and 1,000 degrees C using self-built thermal fatigue equipment. The temperature, stress, and crack propagation driving force of the V-notch specimen were discussed in detail. Results show that the thermal fatigue crack initiation life gradually decreases with the increase of the peak temperature. Oxidation caused by high temperature will weaken alloy's strength and accelerate its crack propagation. Higher peak temperature will make the crack propagate faster and the thermal deformation at V-notch end easier to accumulate. At last, there is a good consistency between fitting curves from the modified Paris formula and the experiment results. Thermal fatigue failure behaviors of GH3230 superalloy were studied under three peak temperatures.Thermal fatigue crack initiation life gradually decreases with the increase of the peak temperature.Higher peak temperature will make cracks propagate faster and thermal deformation easier to accumulate.There is a good consistency between fitting curves from the modified Paris formula and experiment results.