In situ 3D X-ray microtomography of laser-based powder-bed fusion (L-PBF)—A feasibility study

Abstract

X-ray microtomography can be used to characterise objects undergoing fabrication by additive manufacturing. During the layer-by-layer building process, it can provide key information about geometry, roughness and it can even reveal typical defects such as lack-offusion porosity, gas pores or cracks. Usually, objects are built with varied processing parameters and then characterised post-mortem. In the present work, we describe our custom-designed additive manufacturing chamber allowing in situ 3D-non-destructive characterisation to be performed during layer-by-layer construction using synchrotron X-ray microtomography. Scans before (subsequently to powder deposition) and after local laser melting are acquired for every layer. A few examples of such a characterisation demonstrate the ability of the setup to reproduce conditions close to those used in conventional laser powder-bed fusion devices and to reveal key phenomena.

In-situ measurement and monitoring methods for metal powder bed fusion: an updated review

“…Similar comparisons between in-situ reconstructed porosity maps and X-ray CT inspections have also been The possibility of detecting in-situ individual pores was further discussed by Lhuissier et al (2020) who used the same proposed in-situ X-ray CT approach in L-PBF. However, a comparison between in-situ detected pores and pores observed in ground truth post-process inspection has not been carried out (to our knowledge).…”

“…Other researchers investigated the use of a similar sensing setup for X-ray diffraction measurement, which allows the characterisation of strain and stress formation and phase transformations (Schmeiser et al 2020, Uhlmanna et al 2017, Zhao et al 2017. One study also explored the feasibility of in-situ micro-tomography (Lhuissier et al 2020).…”

Miniature laser powder bed fusion system for in situ synchrotron x-ray micro-computed tomography experiments at the European Synchrotron Radiation Facility

“…A virtual powder removal procedure, see more details in Ref. 20, has been developed and makes it possible to achieve 3D rendering of the fabricated objects throughout the layer-by-layer building sequence. the virtual view is a 3D view of the built object as it would be observed if the powder bed was removed.…”

“…We have recently designed and introduced a miniature L-PBF replicator to extend the in situ characterization of powder bed fusion AM-processes to 3D 20 to fill in this technology gap. Few illustrative examples based on single tracks were used to demonstrate the technical feasibility of the approach.…”

“…Few illustrative examples based on single tracks were used to demonstrate the technical feasibility of the approach. 20 This new characterization approach not only fills a technical gap but also allows key information that is not yet available to be collected in conditions that are thought to be closer to the ones of more commercial machines.…”