In order to produce superior feed stock for the forging of turbine dis
ks and other components, it is necessary to better understand the effe
ct of deformation parameters on the hot deformation behavior of IN718
during thermomechanical processing. Superalloy IN718 is a strain-rate
sensitive material. In the present work, isothermal constant speed com
pression tests of superalloy IN718 were conducted using a computer-con
trolled MTS machine at temperatures of from 960 to 1040 degrees C, wit
h initial strain rates of from 0.001 to 1.0s(-1), to engineering strai
ns of from 0.1 to 0.7. The variation of flow stress with initial strai
n rate was analyzed in the paper. It was found that there was an obvio
us power-law relationship between how stress and initial strain rate.
From the results of these tests, a mathematical model showing the stra
in-rate hardening behavior of superalloy IN718 at elevated temperature
s was developed. At the same time, the flow stress calculated from the
model was compared with experimental results and the effect of deform
ation parameters on the related coefficients was analyzed. (C) 1997 El
sevier Science S.A.