STRAIN-RATE HARDENING BEHAVIOR OF SUPERALLOY IN718

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.