Effect of process parameters on microstructure and properties of Inconel-718 superalloy fabricated by wire-arc direct energy deposition technique

Abstract

As critical aero-engine components, closed impellers demand precision manufacturing to ensure reliability under extreme conditions. Traditional casting and powder-bed additive manufacturing face challenges in defect control and cost-effectiveness. Wire-arc directed energy deposition offers high material utilization and deposition rates for near-net-shape fabrication, yet its inherent high heat input induces microstructural defects such as Laves phase segregation in Inconel-718 superalloy. This study investigates CMT + P-based wire-arc DED processing of Inconel-718, focusing on energy density effects spanning 360–540 J/mm on thin-wall geometry, microstructure, and mechanical properties. Energy-dispersive X-ray spectroscopy and XRD analysis reveal that increased energy density expands primary dendrite arm spacing from 4.68 to 18.97 μm and Laves phase area fraction from 3.12 to 8.10 %, correlating with reduced as-deposited tensile strength of 725 ± 45 MPa. Post-deposition solution-aging heat treatment enhances ultimate tensile strength to 1354 ± 54 MPa. The mechanical properties of Inconel-718 deposited via CMT + P were compared with those produced by the conventional CMT process. Mechanical property benchmarking against Inconel-718 casting and forging standards provides actionable insights for industrial process optimization.

Keywords

• Wire arc-based DED
• CMT+P
• Inconel-718 superalloy
• Microstructure
• Mechanical properties