Effect of strain rate on hot deformation characteristics of GH690 superalloy

In order to clarify the effect of strain rate on hot deformation characteristics of GH690 superalloy, the hot deformation behavior of this superalloy was investigated by isothermal compression in the temperature range of 1000-1200 degrees C and strain rate range of 0.001-10 s (1) on a Gleeble-3800 thermo-mechanical simulator. The results reveal that the flow stress is sensitive to the strain rate, and the dynamic recrystallization (DRX) is the principal softening mechanism. The strain rate of 0.1 s(-1) is considered to be the critical point during the hot deformation at 1000 degrees C. The DRX process is closely related to the strain rate due to the adiabatic temperature rise. The strain rate has an important influence on DDRX and CDRX during hot deformation. The nucleation of DRX can be activated by twin boundaries, and there is a lower fraction of Sigma 3(n) (n=1, 2, 3) boundaries at the intermediate strain rate of 0.1 s(-1).