Ultrasonic Vibration-Assisted Laser Engineered Net Shaping of Inconel 718 Parts: A Feasibility Study

Laser engineered net shaping (LENS) has been applied as a key technology in direct manufacturing or repairing of high added- value metal parts. Recently, many investigations on LENS manufacturing of Inconel 718 parts have been conducted for potential applications of the aircraft turbine component manufacturing or repairing. However, fabrication defects such as pores, cavities, and heterogeneous microstructures always exist in the parts, affecting part qualities and mechanical properties. Therefore, it is crucial to LENS-manufacture Inconel 718 parts in a high-quality and high-efficiency way. Ultrasonic vibration has been introduced into various melting metal solidification processes for process improvements. However, there are no reported investigations on ultrasonic vibration-assisted (UV-A) LENS of Inconel 718 parts. In this paper, for the first time, UV-A LENS is proposed to reduce the fabrication defects of Inconel 718 parts. The experimental investigation is conducted to study the effects of ultrasonic vibration on microstructures and microhardness of the parts fabricated by UV-A LENS and LENS without ultrasonic vibration. The results showed that ultrasonic vibration could reduce the porosity, refine the microstructure with a smaller average grain size, and fragment the detrimental phase with a uniform distribution, thus enhancing the microhardness of the fabricated parts.