Experimental Research on the Fatigue Behavior of GH4169 Superalloy Containing Artificial White Spot Defects

ABSTRACT Dirty white spots (DWSs) in superalloys have caused aviation accidents, posing a challenge to aviation safety and reliability. However, the influence of DWS defects on the fatigue performance of superalloy components remains unclear, primarily because naturally occurring DWS defects are extremely rare. To investigate the influence of DWS on fatigue life, this study conducted fatigue experiments on GH4169 superalloy specimens containing artificial DWSs. The results indicate that hot isostatic pressure (HIP) can bond artificial DWS with GH4169, with carbon oxides formed at the bonding interface. These carbon oxides do not generate detectable ultrasonic signals, but they act as crack initiation sites during fatigue tests. Based on elastic finite element simulations, a phenomenological model was established to describe the fatigue life of specimens with artificial DWSs. The experimental fatigue life data were within the 95% prediction interval of the phenomenological model. This study provides a reference for analyzing the problem of DWSs in engineering applications.