Improving the Ductility of Electron Beam Welded Joint between Additive Manufactured and Forged Ti‐6Al‐4V Alloys through Heat Treatment

Laser melting deposition fabricated Ti‐6Al‐4V (TC4‐LMD) demonstrates exceptional mechanical properties and has been widely adopted in aerospace applications. However, the dimensional constraints of additive manufacturing equipment necessitate welding of TC4‐LMD components with other parts fabricated via conventional processes (e.g., forging). Significant microstructural and mechanical property gradients across distinct zones of a dissimilar welded joint frequently lead to poor overall mechanical performance. This study investigates the microstructural characteristics and mechanical behavior of electron beam welded joints between TC4‐LMD and forged damage tolerance TC4 (TC4‐DT). Digital image correlation (DIC) analysis is employed to elucidate localized strain distribution patterns during tensile deformation of the joint. Postwelding solution‐aging heat treatments with varying solution temperatures and cooling rates are used to tailor the properties of the joint. Results indicate that pronounced heterogeneous microstructures are formed in the initial joint, which substantially deteriorates the tensile properties, particularly ductility. Through solution heat treatment at 950 °C followed by air cooling and aging, the heterogeneous microstructure has been largely eliminated. Furthermore, fine β‐transformed structures are precipitated during the postwelding heat treatment, which also contribute to enhancing the strength‐ductility synergy.