Foreign object damage characteristics and their effects on high cycle fatigue property of Ni-based superalloy GH4169

In this study, high-speed ballistic impact tests were conducted on GH4169 alloy samples with the aeroengine compressor blade leading-edge feature to simulate the notch-type foreign object damages (FOD). Macroscopic and microscopic characterization of FOD and high cycle fatigue tests were performed to investigate the effect of FOD depth on GH4169 alloy fatigue strength along with numerical analysis using the Kitagawa-Takahashi diagram. Results show that the incident side of notch-type FODs is relatively smooth, whereas the exit side is rugged. The FOD depth ranges from 0.18 to 1.33 mm, and the fatigue strength of damaged samples is 37.93% - 97.04% of the undamaged samples. As the FOD depth increases, damage length, material losses, and the stress concentration coefficient of the FOD increase significantly and accompanied by the increasing of adiabatic shear bands, micro voids, and cracks, resulting in fatigue strength reduction. Numerical analysis indicates that the Kitagawa-Takahashi diagram can provide a basic model for the design of FOD tolerance.

Automated summary

This study conducted high-speed ballistic impact tests and fatigue tests on GH4169 alloy samples to investigate the effect of FOD depth on fatigue strength. It was found that as the FOD depth increases, the damage length, material losses, and stress concentration coefficient also increase, resulting in a reduction in fatigue strength. The study also showed that the Kitagawa-Takahashi diagram can be used as a basic model for the design of FOD tolerance.