Fatigue Life Prediction of Additively Manufactured Superalloy on a Rocket's Engine

Abstract

Additive Manufacturing (AM) has revolutionized the production of complex parts, particularly for superalloys in the aerospace industry due to their strength, corrosion resistance, and high-temperature performance. LPBF is notable for its precise control over complex geometries, with key parameters like laser power and scanning speed affecting the final product's quality. This study examines how build orientation, high stress ratios, and surface roughness impact the fatigue life of superalloy. Vertical and diagonal specimens were printed with identical heat treatments to isolate these variables. The diagonal specimens showed higher UTS but lower ductility compared to the vertical ones. Fatigue tests revealed that increased surface roughness in diagonal specimens reduced HCF performance, while their strength improved LCF behavior. Crack initiation was primarily at the surface in HCF, while internal defects caused some LCF failures. The proposed fatigue models aligned well with experimental data, offering valuable insights for future research.