Effect of Film-Cooling-Hole Inclination on the Creep Performance of IN-738 Specimens.

To investigate the effect of film-cooling-hole inclination on the creep performance of nickel-based superalloy IN-738 specimens, this study designed samples with film-cooling holes at four inclination angles: 0°, 30°, 45°, and 60°. High-temperature creep tests were conducted, and the fracture morphologies of the failed specimens were analyzed using scanning electron microscopy. The results indicate that under conditions of 800 °C and 350 MPa, the inclination angle of the film-cooling holes significantly influences the creep performance of the specimens, with creep lifetimes ranking in descending order as 0° > 60° > 45° > 30°. A fracture analysis revealed that creep failure in specimens with film-cooling holes primarily resulted from stress concentration at the hole edges, where cracks and voids frequently initiated. The creep fractures exhibited dimple-type failure characteristics localized around the film-cooling holes due to stress concentration. Simulations based on the K-R damage model were performed for the four different inclination angles, confirming the existence of stress concentration around the film-cooling holes. The numerical analysis results closely matched the experimental data. Furthermore, the node stress method was used to predict the creep rupture life of specimens with film-cooling holes, demonstrating high accuracy in life prediction.