Deformation behavior and constitutive model for high temperature compression of a newly type of Ni3Al‐based superalloy

Abstract

AbstractIn order to investigate the hot deformation mechanism of a newly development Ni3Al‐based superalloy, hot compression tests at temperatures between 1100 °C–1250 °C and the strain rates of 0.001 s−1–1.0 s−1 were conducted. The results show that the curves of true stress‐strain indicate the thermal deformation is a typical dynamic recrystallization process, which the peak stresses and steady‐state stresses increase with decreasing temperatures and increasing strain rates. The softening mechanism is mainly dynamic recrystallization. The experimental data of peak stresses and steady‐state stresses is employed to calculate the constants in the Arrhenius equation. The steady‐state stresses are considered more reasonable for solving the parameters in the Arrhenius equation. Based on the constitutive equation obtained, the calculated values of steady‐state stresses match well with the experimental values at the strain rates of 0.001 s−1, 0.01 s−1 and 0.1 s−1, whereas there exists much deviation at 1.0 s−1. For the sake of accuracy of predicted results at 1.0 s−1 strain rate, a modified Zener‐Hollomon parameter Z’ is introduced. The results show that the modified constitutive equations established in this study could well predict the value of steady‐state stress in hot deformation of the newly development Ni3Al‐based alloy.