Research on high temperature deformation behavior of new type nickel-based P/M superalloy

The high temperature deformation behavior of a new type 3rd generation nickel-based powder metallurgy(P/M) superalloy FGH98 I was studied in the different deformation temperatures (950~1150°C) and different strain rates (0.0003~1 s^-1) using Gleeble-1500 thermal simulator. It developed the dynamic RTT curve and established the constitutive relationship of hot deformation. The results show the flow stress decreases with increasing deformation temperature and decreasing strain rate. The flow stress represents as the characteristic of dynamic crystallization with the increasing of strain at the deformation temperature lower than 1100°C and strain rates higher than 0.0003 s^-1. The beginning time of dynamic crystallization has no linear relationship with deformation temperatures in the condition of the strain rates lower than 0.01 s^-1. Besides, the experiments verify that the sinh model including the variable of strain reflects the changing law of flow stress during the hot deformation process.