Prediction method for creep life of thin-wall specimen with film cooling holes in Ni-based single-crystal superalloy

Considering the effects of numbers and drill processes of film cooling holes, the effect of a multiaxial stress state on the creep behavior of Ni-based single-crystal superalloy was investigated. The thin-wall plate specimens with film cooling holes, including multiholes and a single central hole, have been designed. The drilling processes are electro stream machining (ESM), electrical discharge machining (EDM) and laser drilling (LD). The results show that creep lives were longer in the thin-wall specimens with a single central hole and shorter in specimens with multi-holes due to the multihole interference effect. Under the same stress and temperature, the specimens with multiholes using the LD process have the longest creep lives compared with the other two processes. To predict the creep life of a specimen with film cooling holes, a creep damage constitutive model under the crystal plasticity framework was proposed by adding geometric structure variables beta and m. Coupling with the modified skeletal point stress method (SPSM), the creep rupture lives of the specimens with film cooling holes were well predicted. The error of creep life between the finite element (FE) calculation and experimental results is within 28.03%.