Quantifying the Effects of Carbides and Pores on Fatigue Damages of Ni-Based Single Crystal Superalloys at Elevated Temperature Using X-Ray CT Scans

Although the effects of pores and carbides on the high temperature fatigue performance of nickel-based single crystal superalloys have been studied for decades, few studies have statistically compared their damage effects and identified the most detrimental factors. X-ray computed tomography has been used to collect the microstructure variations while the fatigue damage happens at high temperature. Combining image registration and deep learning algorithm, both carbides and pores have been extracted and quantified by a new damage factor. It shows that pores are more harmful than carbides during crack initiation, and carbides are more significant than pores during the crack propagation stage at elevated temperatures. Furthermore, by developing a multiple linear regression model, the damage effects of pore size, morphology, spacing, and distance to the sample surface on the crack initiation and propagation stage were differentiated. It is found that pore spacing is the most important factor for crack initiation.