Study On The Hot Deformation Behavior And Dynamic Recrystallization Behavior Of FGH96P/M Superalloy

FGH96is the second generation powder metallurgy (P/M) superalloy designed by the principle of damage tolerance. Compared with the first generation superalloy, the amount of y phase is reduced and the grain size is readjusted in FGH96P/M superalloy, so its strength is reduced properly and its resistance to crack growth has been improved. FGH96P/M superalloy is the key material which could meet the request of high thrust-weight ratio engines and work stably in a long time. The tradition fusion welding methods are not suitable for the connection of these components any more. As a kind of solid joining technique, inertia friction welding (IFW) has been widely accepted as the standard welding methods to connect the FGH96P/M superalloy components. FGH96P/M superalloy has three different structure statuses:HIP, solution treated, solution and aging treated. The difference of microstructure has a direct effect on the hot deformation behavior and dynamic recrystallization (DRX) behavior during the hot deformation process of FGH96P/M superalloy, then the mechanical properties are affected further. In order to obtain the best weldments, the hot deformation behavior and DRX behavior of different structure statues FGH96P/M superalloy during the single hot compression tests need to be studied.In this paper, the single hot compression tests of different structure statues FGH96P/M superalloy were carried out at the temperature of1000-1150℃and strain rate ranging from0.001s-1to10s-1. The effects of deformation parameters on the hot deformation behavior were investigated. According to the strain-stress curves obtained from the experiments, the constitutive models of three structure statues FGH96P/M superalloy during the hot deformation were established based on the thermal plastic deformation theories.The grain size under different deformation parameters of three structure statues was counted and the effects of deformation parameters on the DRX behavior during hot deformation were investigated. The DRX kinetics models of three structure statues FGH96P/M superalloy during the hot deformation were established based on the DRX model of Sellars.The comparison results of three structure statues FGH96P/M superalloy show that the stress level of solution treated FGH96P/M superalloy is highest and the stress level of HIP FGH96P/M superalloy is lowest under the low deformation temperature (1000℃and1050℃). However, the stress-strain curves show little difference under high deformation temperature (1100℃and1150℃). DRX occurred completely in all of the samples when the deformation temperature exceeds1100℃. The grain size show little difference under low temperaturt (1100℃) while the grain size of solution treated samples is smaller than the other two statuses under high temperature (1150℃), which implies that the deformation parameters have the most effect on the grain size of solution treated FGH96P/M superalloy samples. The comparison results of the stress-strain curives and grain size of the three statuses of FGH96P/M superalloy reveals that the solution and aging FGH96P/M superalloy is suitable for IFW most.