Laser Induced Breakdown Spectroscopy for In-Situ Monitoring of Laser Powder Bed Fusion Processing

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Date

2023

Authors

Krantz, Justin T.
Lough, Cody S.
Brown, Ben
Yang, Jinyu
Go, David B.
Landers, Robert G.
Kinzel, Edward C.

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Publisher

University of Texas at Austin

Abstract

A major challenge for laser powder bed fusion processes is identifying and addressing flaws in the as-built part. In-situ monitoring of the magnitude of radiation emitted from the vicinity of the melt pool largely corresponds to the temperature field. This has been correlated with the local porosity and microstructure of the part. However, the composition of the part can also vary, either because of processing conditions or differences in the powder. Spectroscopy has the potential to resolve material composition because spectral lines corresponding to atomic species present in the metal can be clearly observed. The line emission phenomena from ionization and excitation in the vapor plume is limited under standard LPBF conditions. Laser induced breakdown spectroscopy (LIBS) uses a pulsed laser to produce a localized plasma. This is demonstrated in LPBF using an ultrashort pulsed (USP) laser coaligned to the continuous wave (CW) process laser. The USP laser can be used to probe the melt pool and plume in-process, creating a plasma that is independent of the process conditions. This probing process has minimal adverse effects on the melt pool. LIBS can provide feedback about the local species content through time resolved spectroscopy and provides the potential for voxelwise composition information to be obtained from the material.

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