Microstructural evolution and mechanical behavior of friction stir welded additively manufactured Haynes 282 Ni superalloy

• FSW successfully applied to as-built EB-PBF Haynes 282 Ni-superalloy. • Achieved 100% joint efficiency in both as-welded and PWHT conditions. • Novel Si 3 N 4 hemispherical tool enables defect-free solid-state joining. • Grain refinement from ∼ 170 µm to ∼ 7–8 µm via dynamic recrystallization. • PWHT restores γ′ phase, boosting UTS to ∼ 1258 MPa through re-precipitation. Haynes 282 (H282) is a gamma prime (γ′) strengthened nickel-based superalloy with applications in jet engine turbine components and other aerospace applications. Electron beam powder bed fusion (EB-PBF) additive manufacturing (AM) enables efficient fabrication of H282 by promoting in-situ γ′ precipitation. However, integrating AMed parts with conventionally made components is cost-effective and often necessary, requiring reliable joining methods. This study explores friction stir welding (FSW) of as-built EB-PBF H282 using a novel hemispherical Si 3 N 4 tool tilted toward the retreating side. A joint efficiency of 100 % in ultimate tensile strength was achieved in both as-welded and post-weld heat-treated (PWHT) conditions. UTS increased from ∼ 1000 MPa (as-built) to ∼ 1039 MPa after FSW, and ∼ 1258 MPa after PWHT. FSW induced dynamic recrystallization, refining grain size from ∼ 170 µm to ∼ 7 µm in the stir zone, while also eliminating typical AM defects like porosity and lack of fusion. During FSW, γ′ precipitates dissolved in the SZ but were restored during PWHT along with other strengthening phases—Ti-, Mo-rich MC, and Cr-rich M 23 C 6 carbides. The main strengthening mechanisms were Hall-Petch, dislocation, and precipitation strengthening. Results are compared to FSW of solution-annealed AM H282 and wrought H282, confirming FSW’s effectiveness in enhancing microstructural and mechanical performance.