Modeling of the fatigue crack growth of nickel-based superalloy using a constraint-based approach considering thickness

Abstract

Varying thickness configurations have been applied to aero-engine turbine components. As a result, the thickness effect on the crack behavior must be considered in the damage tolerance method. The thickness effect remains a topic of discussion and needs further investigation due to limited studies on nickel-based superalloys. This study develops a fatigue crack growth (FCG) model which considers the thickness effect of nickel-based superalloy GH4169. FCG experiments were performed with specimens of different thicknesses at different temperatures. The results indicate that thickness significantly affects the FCG of GH4169, and the thickness effect is strongly temperature-dependent. A constraint-based model was employed to describe FCG with different thicknesses, emphasizing the influence of the stress state induced by the specimen thickness. Although this model works at room temperature, it fails to describe the crack growth at elevated temperatures. Therefore, a modified model was proposed to consider different temperatures. Successful predictions using the modified model can be achieved for different temperatures. This study offers new insights on quantifying the thickness effect on FCG of nickel-based superalloys.