Abstract: Objective This study aims to investigate microstructure evolution and its effect on mechanical properties of FGH96 superalloy during inertia friction welding process. Methods Optical microscopy, scanning electron microscopy, and tensile testing were employed to analyze microstructure and tensile strength of inertia friction welded joints of FGH96 alloy rings with 60 mm outer diameter and 30 mm inner diameter. Results The results indicated that at an axial pressure of 300 MPa, interface weak bonding defects were present on both sides of welded joints, with a tensile strength of 1 507.93 MPa. When axial pressure was increased to 350 MPa and 400 MPa, no interface weak bonding was observed in the center or both sides of weld, tensile strengths of welded joints were 1 511.10 MPa and 1 497.59 MPa, respectively. At a moment of inertia of 340 kg·m², tensile strength of welded joints was 1 483.12 MPa. Conclusion Increasing friction pressure or decreasing moment of inertia accelerates dissolution of γ׳ phase into matrix while promoting grain refinement in weld zone, which adversely affects tensile strength of welded joints.