Abstract: Based on elastic-plastic finite element theory, 3D plastic body/plastic body friction pair model was used to establish a finite element model of inertia friction welding process of FGH96 superalloy tube by considering the difference in heat dissipation conditions on both sides of workpieces during actual welding process. Distribution of transient temperature field and axial stress field during welding was calculated. Effect of initial rotation speed, upsetting force and inertia moment on temperature field and flash morphology of welded joints was investigated. The error between simulated flash topography and test weldment was only 5%, which verified reliability of the model. The simulated results showed that during inertia friction welding process, friction interface was heated up rapidly, peak temperature could reach 1 335 ℃, and plastic deformation mainly occurred in the area 4 mm away from interface, where the axial temperature gradient was large. The compressive stress value near friction interface gradually decreased from the center to the edge, stress state of interface edge changed from compressive stress to tensile stress, and root of the flash had compressive stress concentration due to extrusion deformation. Increasing initial speed and inertia moment could increase welding heat input, friction time, peak temperature and flash extrusion. Increasing upsetting force could improve efficiency of converting mechanical energy into thermal energy, shorten friction time, and raise axial shortening amount and flash curls.Highlights: Plastic body/plastic body finite element model can consider interaction of contact surface force comprehensively. A more realistic 3D double plastic body model was established to simulate inertia friction welding process of FGH96 superalloy annular workpiece.