Predicting the flow stress behavior of Ni-42.5Ti-3Cu during hot deformation using constitutive equations

The hot deformation behavior of ternary Ni-42.5Ti-3Cu alloy was modeled. Hot compression tests were carried out at the temperatures from 800 A degrees C to 1000A degrees C and at the strain rates of 0.001 s(-1) to 1 s(-1). The experimental results were then used to determine the constants for developing constitutive equations. There was an unacceptable fitting between the predicted and experimental results using Zener-Hollomon parameter in a hyperbolic sinusoidal equation form. The mismatches among the experimental and predicted results were observed almost for all tested conditions. By modifying the Zener-Hollomon parameter for the compensation of strain rate, a very good agreement was achieved between the predicted values and experimental ones. Both predicted and experimental stress-strain curves illustrate the occurrence of dynamic recrystallization. Also, in both cases, the peak and steady state stresses raised with decrease of temperature and increase of strain rate. The very good agreement between the measured and predicted results indicates the high accuracy of developed model and constitutive equations which can be used for predicting and analyzing the hot deformation behavior of Ni-42.5Ti-3Cu.