Effect of inter-hole interference on creep rupture behavior and microstructural evolution of a nickel-based single crystal superalloy

The arrangement of film cooling holes (FCHs) in nickel-based single crystal turbine blades directly affects the creep life of the structure. To investigate the effects of hole arrangement on the creep behavior and failure mechanism of a nickel-based single crystal superalloy, creep tests were carried out on specimens containing square and rhombus arrays of film cooling holes. The post-fracture morphology and microstructural evolution were then characterized. The results show that the inter-hole interference induced by the hole arrangement has a significant effect on the creep-fracture path. To analyze the deformation behavior around the holes under different arrangements, a crystallographic-slip-based creep-damage framework was used. The simulations indicate that the difference in fracture mode between the two arrangements is closely associated with the difference in inter-hole interference intensity and the resulting distributions of local resolved shear stress and resolved shear strain, slip-band evolution, and damage accumulation pathways. The simulation results show good agreement with the experimental observations, supporting the proposed interpretation of arrangement-dependent creep rupture behavior in film cooling hole structures.