Zhou Jun Zhang Yongqiang ^* Qin Feng Zhang Xuelong ^* Wang Hao ^* Liu Ze ^* Zhang Wenhan ^* Huang Caiyan ^* Zhang Chunbo ^*

• Harbin Welding Institute Limited Company，CAM, Harbin, China

Nickel-based superalloys are critical for aerospace engines due to their high-temperature strength, oxidation, and corrosion resistance. This study examines the microstructural evolution and mechanical properties of inertia friction welding (IFW) joints between FGH101 powder superalloy and IN718 deformed superalloy. IFW is preferred for its efficiency and superior joint quality. During welding, significant plastic deformation occurs, forming symmetrical ear-shaped flash on the IN718 side and minor upsetting on the FGH101 side, with a wavy interface due to heat dissipation. Microhardness analysis shows higher hardness at the weld interface, with a sharp drop near the HAZ on the IN718 side due to phase re-dissolution, while FGH101 exhibits quicker recovery. Post-weld aging treatments enhance hardness and strength through γ' and δ phase precipitation in FGH101 and γ'' phases in IN718. Room temperature tensile tests reveal impressive strength with plastic failures in IN718 base metal, whereas elevated temperatures shift failures to the weld zone without necking. Fatigue tests show varied lifespans, with fractures initiated either at stress concentrators or within the FGH101 base metal far from the weld center. Scanning electron microscope (SEM) analysis confirms mixed-mode fracture patterns, underscoring the importance of microstructure on joint performance. These findings provide insights for optimizing IFW parameters for superior weld quality in aerospace components.