Microstructural evolution and high-temperature deformation behavior of wire arc additively manufactured Inconel 718 forging Preforms: Toward a hybrid Additive–Forging Process

Hybrid manufacturing routes combine additive manufacturing (AM) with conventional methods. They offer a potentially faster, more economical pathway to produce engineered components with performance that equals or exceeds that of wrought or cast counterparts. In these strategies, AM allows fabrication of preform geometries without the need for custom tooling or feedstock. Conventional post-processing mitigates AM-specific issues such as anisotropic mechanical properties, residual stresses, porosity, and the presence of large columnar grains with pronounced texture. This study focuses on a hybrid AM-forging approach, in which the hot deformation behaviour of wire arc additive manufacturing (WAAM) processed Inconel 718 preforms was evaluated using hot compression tests (HCT). Cylindrical samples from WAAM deposited walls were hot compressed in a Gleeble® 3800 physical simulator at 927–1100 °C and strain rates of 0.01–5 s⁻¹. The evolution of microstructural anisotropy and flow behavior under these conditions was examined using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). Dynamic recrystallization (DRX) was dominant in specimens deformed at 5 s⁻¹, while dynamic recovery (DRV) prevailed at 0.01s⁻¹. The size of recrystallized grains during hot deformation was predicted using a phenomenological model based on the Zener-Hollomon parameter. The results revealed that grain size varies as a function of strain, enabling the tailoring of the grain structure of components forged from AM preforms. Processing maps indicated a power dissipation efficiency (η) of ∼0.33 in a stable hot-working regime, consistent with DRX-dominated microstructural refinement.