Microstructure Characterization of Inertial Friction Welding Zone for Nickel-Based Superalloy FGH96

Abstract

The inertial friction welding of similar PM FGH96 superalloy was investigated. The inertial friction welding introduced steep thermal gradients of welding zone for PM FGH96 superalloy, the whole welding process only needed several seconds, therefore, it’s a fast heating and cooling completely recrystallization process. Dramatic changes in the microstructure were observed over a narrow weld zone, which across the weld interface was measured to be about 1.0-1.2mm. Significant changes in the secondary and tertiary γ′ distribution can be observed over the first 2mm from welding line, while very fine tertiary γ′ particles precipitated in a unimodal size distribution and in a high density at welding line. The fine secondary re-precipitated γ′ under fast cooling was spherical in shape, which gradually transformed into elliptical, cube with the distance from welding line. No significant texture or grain distortion was observed in the extensively plastically deformed region due to recrystallization.