High temperature deformation constitutive model of nickel-based alloys for 700 °C A-USC power plants.

Nickel-based superalloys have excellent high temperature resistance and corrosion resistance, and can be used as candidate materials for superheater and reheater pipes of advanced ultra-supercritical thermal power units. This research focuses on the hot-compression behavior of nickel-based alloys in the deformation process range of strain rate 0.01–10 s⁻¹, deformation temperature 950–1150 °C, and deformation amount of 60%. The stress-strain curve collected during the hot compression process showed an obvious unimodal phenomenon, and showed obvious hardening and softening characteristics. The flow stress is very sensitive to the change of strain rate. The experimental results are used to develop plastic flow stress models for various existing constitutive models, namely Modified Johnson-Cook (MJC), Modified Zerilli-Armstrong (MZA), Strain-Compensated Arrhenius (SCA), Modified Fields-Backofen (MFB), Modified Hansel-Spittel (MHS), Piecewise Function (PF). Combined with correlation coefficient, average absolute relative error and relative error, the prediction accuracy of each model was further analyzed, and it was found that SCA and PF had better accuracy. The reasons for the errors of each model are further discussed. In addition, compared with SCA model, PF model has higher accuracy in predicting hardening stage and less calculation. The PF model has great potential in predicting the flow properties of materials. [ABSTRACT FROM AUTHOR]