Hot deformation and constitutive model of as-cast Ni–Cr–Co nickel-base alloy

Abstract

Abstract Nickel-based superalloys are widely used in thermal power, nuclear power, aerospace and other fields due to their excellent properties. Since the deformation resistance of Ni–Cr–Co superalloy is large and the forming range is narrow, the hot deformation behavior of Ni–Cr–Co superalloy was studied by hot compression experiments on a Gleeble-3800 under different deformation conditions (deformation temperature: 950–1200 °C, strain rate: 0.01–10 s−1, and deformation: 60 %). The modified Johnson–Cook, modified Zerilli–Armstrong and strain compensated Arrhenius models were constructed based on the stress–strain curves corrected for friction and temperature. The correlation coefficient (R) and average absolute relative error (AARE) were compared to verify the accuracy of the model. The results showed that the strain compensated Arrhenius model had high accuracy, the modified Zerilli–Armstrong had high accuracy in predicting the flow behavior above 1100 °C, while the modified Johnson cook had high accuracy only under the reference conditions. Electron back-scattered diffraction analysis showed that high-angle grain boundaries formed when the low-angle grain boundaries piled up to a certain extent, which is beneficial for refining the as-cast microstructure, and the increase in strain rate was beneficial for refining the microstructure and promoting the occurrence of recrystallization.