In situ interlayer hot forging arc-based directed energy deposition of Inconel® 625: process development and microstructure effects

• Published in: Additive manufacturing Vol. 66; p. 103476
• Main Authors: Farias, Francisco Werley Cipriano, Duarte, Valdemar R., Felice, Igor Oliveira, Filho, João da Cruz Payão, Schell, Norbert, Maawad, Emad, Avila, J.A., Li, J.Y., Zhang, Y., Santos, T.G., Oliveira, J.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25.03.2023
• Subjects: Equiaxed grains; Heat treatment; Hot forging; Hybrid process; Inconel; Wire arc additive manufacturing; Heat treatment; Equiaxed grains; Wire arc additive manufacturing; Hybrid process; Inconel; Hot forging
• ISSN: 2214-8604; 2214-7810
• DOI: 10.1016/j.addma.2023.103476

The typical as-built coarse and cube-oriented microstructure of Inconel® 625 parts fabricated via arc-based directed energy deposition (DED) induces anisotropic mechanical behavior, reducing the potential applications of arc-based DEDed Inconel® 625 in critical components. In this sense, the present work aimed to reduce the grain size and texture by applying an in situ interlayer hot forging (HF) combined with post-deposition heat treatments (PDHT). The produced samples were characterized through optical microscopy, scanning electron microscopy coupled with electron backscatter diffraction, synchrotron X-ray diffraction, and Vickers microhardness. Also, a dedicated deformation tool was designed and optimized via a finite element method model considering the processing conditions and thermal cycle experienced by the material. It is shown that the in situ interlayer deformation induced a thermo-mechanical-affected zone (dynamic recrystallized + remaining deformation, with a height of ≈ 1.2 mm) at the bead top surface, which resulted in thinner aligned grains and lower texture index in relation to as-built DED counterpart. In addition, the effects of solution (1100 °C/ 1 h) and stabilization (980 °C/ 1 h) PDHTs on the Inconel® 625 HF-DEDed parts were also analyzed, which promoted fine and equiaxed static recrystallized grains without cube orientation, comparable to wrought material. Therefore, the HF-DED process significantly refined the typical coarse and highly oriented microstructure of Ni-based superalloys obtained by arc-based DED.