A new experimental and simulation methodology for prediction of recrystallization in Ni-based single crystal superalloys during investment casting

A new methodology involving both experimentation and modeling to predict the recrystallization of nickel-based single-crystal superalloy parts after subsequent heat treatment is presented. Anisothermal mechanical tests are used to provide further validation of a thermal-elasto-viscoplastic behavior model, and process-specific values of the thermal expansion coefficient. Critical test specimens are casted, and modeled to monitor the thermal-mechanical histories of interesting zones. The proposed model is capable of predicting higher plasticity locations, consistently with the occurrence of recrystallization. Critical plasticity paths for recrystallization are identified, defining three regions: unrecrystallized, transition and recrystallized zones. Phenomenological-based numerical plastic strain and energy criteria for AM1 single-crystal superalloy are built, and validated on an industrial case. The proposed methodology provides a systematic approach for part design and process parameters optimization, enabling recrystallization to be predicted and hence avoided.