Abstract: FGH98 alloy was welded by inertia friction welding.The effects of heat treatment on microstructure and mechanical properties of the welded joint were studied.The results show that the weld zone(WZ)of original welded joint is mainly composed of γ phase and γ' phase, the grain size decreases compared with the base metal, γ' phase dissolves back during welding, and the size and quantity of residual γ' phase decreases obviously.The hardness value of the welding area of the as-welded joint is the highest, and the hardness decreases in the central area of the welding area, and the microhardness of the welded joints does not change significantly after heat treatment.The tensile yield strength of welded joint after heat treatment at room temperature is above 1 130 MPa, which is more than 93% of that of the base metal.The tensile strength is above 1 616 MPa, up to 99% of the base material.While the yield strength at 750 ℃ is above 1 025 MPa, more than 99% of the base metal.The tensile strength is above 1 197 MPa, reaching the same level of the base material.Highlights:(1)The FGH98 nickel-based powder superalloy was welded by inertia friction welding, and the microstructure of the welded joint before and after heat treatment was studied.(2)Combined with microstructure analysis, mechanical properties was studied.