Effect of wall-thickness and control-mode on the thermomechanical fatigue performance of a nickel-based single crystal superalloy

Nickel-based single crystal turbine blades in aero-engines operate under harsh conditions, making them highly susceptible to thermomechanical fatigue (TMF) failure. To investigate the effects of wall-thickness and control-mode on the TMF performance of the nickel-based single crystal superalloy DD6, both in-phase (IP) and out-of-phase (OP) TMF experiments were conducted on hollow tubular specimens with varying wall-thicknesses. The TMF performance of the nickel-based single crystal superalloy DD6, including its deformation behavior and lifetime, was revealed. Furthermore, the relationships between TMF lifetime and wall-thickness, as well as between TMF lifetime and control-mode, were quantified. In addition, a comprehensive dataset was compiled, encompassing low-cycle fatigue, creep-fatigue, and TMF lifetimes of the nickel-based single crystal superalloy DD6 under various experimental conditions, and then a back-propagation (BP) neural network was subsequently employed to predict the TMF lifetime. All fatigue lifetime predictions in the test set fell within the 3 × scatter band, with 96.0 % falling within the 2 × scatter band. And the influence of wall-thickness and control-mode on the TMF lifetime of the nickel‑based single crystal superalloy DD6 was accurately captured.