Deformation behavior and constitutive model for high temperature compression of a newly type of Ni_3AI-based superalloy

摘要

In order to investigate the hot deformation mechanism of a newly development Ni3Al-based superalloy, hot compression tests at temperatures between 1100 degrees C-1250 degrees 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.