Microstructure and Mechanical Property of Thin-Walled Inconel 718 Parts Fabricated by Ultrasonic-Assisted Laser-Directed Energy Deposition

Laser-directed energy deposition (DED) offers significant potential for the additive manufacturing of thin-walled Inconel 718 aerospace components. However, the structural defects readily formed during deposition, along with the extensive precipitation of long-chain Laves phases between coarse dendrites, can severely compromise the mechanical properties of as-fabricated Inconel 718 parts. To address this, an ultrasonic-assisted DED (UDED) method was employed to reduce the deposited structural defects and refine crystalline structures, and the influences of ultrasonic energy fields on the microstructure and mechanical properties of thin-walled Inconel 718 samples were systematically investigated. The results demonstrated that ultrasonic vibration significantly enhances the microstructural quality by reducing porosity and pore size, weakening texture intensity, fragmenting long-chain Laves phases, mitigating severe elemental segregation, and refining matrix grains. Consequently, the UDED thin-walled Inconel 718 sample exhibited an approximately 15% increase in microhardness compared to the conventional DED counterpart, alongside satisfactory strength and ductility. This study highlights the superiority of UDED for microstructure tailoring and its potential for mechanical property regulations in thin-walled Inconel 718 aerospace components.