In-situ Laser ultrasound-based Rayleigh Wave Process Monitoring of DED-AM Metals

ABSTRACT

A laser ultrasound system is integrated into a directed energy deposition additive manufacturing (DED-AM) chamber to use Rayleigh waves for process monitoring in a noncontact layer-by-layer mode. Layers of Ti-6Al-4 V are deposited and then interrogated with ultrasonic Rayleigh waves that are sensitive to flaws and material nonuniformities. The novel integrated material processing and monitoring system is described in detail. Process parameters are intentionally altered to create flaws and anomalies to demonstrate some capabilities of the monitoring system. The generation laser actuates either broadband pulses with a cylindrical lens or narrowband wave packets with a slit mask, which are received in through-transmission mode by a laser interferometer despite the inherent surface roughness. Flaws are detected through comparison to a reference state.

KEYWORDS:

• LUT laser UT
• quality assurance/quality control
• additively manufactured (metallic)

Acknowledgments

The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the NSF [1727292]; U.S. Government [W911W6-17-2-0003].