In-situ layerwise monitoring of electron beam powder bed fusion using near-infrared imaging

• Published in: Additive manufacturing Vol. 38; p. 101767
• Main Authors: Croset, Guillaume, Martin, Guilhem, Josserond, Charles, Lhuissier, Pierre, Blandin, Jean-Jacques, Dendievel, Rémy
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2021; Elsevier
• Subjects: Defects; E-PBF; Engineering Sciences; In-situ; Materials; Near-infrared imaging (NIR); X-ray computed tomography (XCT); Near-infrared imaging (NIR); In-situ; E-PBF; X-ray computed tomography (XCT); Defects
• ISSN: 2214-8604; 2214-7810
• DOI: 10.1016/j.addma.2020.101767

A near-infrared camera (NIR) is employed to monitor layer-by-layer in-situ electron beam powder bed fusion (E-PBF). We aim at demonstrating that such a device allows various kinds of flaws to be reliably captured thanks to qualitative thermal information. Defects such as distortions or uneven top surfaces can be detected in the NIR-images. Information about temperature heterogeneities can also be linked with some distortions occurring near overhangs. Some lack-of-fusion pores are revealed in the NIR-images. Unexpected localized defects appearing as isolated pores elongated along the building direction, and referred to as chimney pores, are also detected in the NIR-images. Pore-like defects can be described in 3D based on the NIR-images. Post-processing non-destructive characterization performed using X-ray computed tomography (XCT) is carried out to validate the information provided by the NIR-images. Comparisons between the 3D images obtained from the NIR-images acquired in-situ and processed using image analysis, and the 3D images obtained through XCT demonstrate that the morphology and spatial distribution of the defects can be reliably captured by NIR-imaging.