In situ X-ray quantification of melt pool behaviour during directed energy deposition additive manufacturing of stainless steel

Abstract

The Directed Energy Deposition Additive Manufacturing (DED-AM) of SS316L was studied using in situ and operando synchrotron X-ray imaging to quantitively understand the effect of processing parameters on the melt-pool morphology and surface quality. It was found that surface roughness of DED-AM builds can result from melt pool surface perturbations caused by changes in the melt flow and build stage motion perturbations. Process maps are developed that quantitatively correlate build quality to process parameters including powder feed rate, laser power and traverse speed. How the AM process parameters control build efficacy is clarified, and the processing conditions required to dampen surface perturbations leading to roughness were determined.

Generalisable 3D printing error detection and correction via multi-head neural networks

“…Applying it to metal AM methods is particularly exciting given the complexity of these processes and the need for quality assurance 63 . Optical techniques are the most common methods used thus far in metal AM for monitoring features such as the powder bed surface and melt pool 64 , 65 . These would be appropriate for use with our methodology and may be especially beneficial for AM of metals that it can be difficult to work with 66 .…”

Synchrotron imaging derived relationship between process parameters and build quality for directed energy deposition additively manufactured IN718

“…A DED-AM process replicator, which faithfully replicates a commercial DED-AM system, was designed to fit onto a synchrotron beamline to capture the key physics during the laser-matter interaction under X-ray. Figure 1 shows a schematic of the experimental set-up and details of the process may be found in [14] . A process map was explored with a range of process parameters including laser power, traverse speed, and powder feed rate listed in Table 1.…”

“…where ℎ 𝑖 is the deviation between a point on the profile and the resultant track height (see [14] for more details of the image processing).…”

Operando tomographic microscopy during laser-based powder bed fusion

“…In particular, operando techniques for LPBF process studies have been developed worldwide at synchrotrons, providing direct "live" insight into this complex manufacturing process 33 . This is re ected by numerous recent publications from such facilities, as the Swiss Light Source (SLS) [34][35][36][37] , Stanford Synchrotron Radiation Light source (SSRL) [38][39][40] Diamond Light Source (DLS) [41][42][43][44] , European Synchrotron Radiation Facility (ESRF) 44,45 and the Argonne National Laboratory's Advanced Photon Source (APS) 33,46 . Operando and in situ diffraction studies performed during LPBF allow for observation of phase transformations occurring prior and after melting and solidi cation as well as evaluation of temperature pro les and cooling rates 35 34,37,47 , while in situ X-ray radiography provides invaluable knowledge about melt pool dynamics [47][48][49][50] and formation of defects such as cracks 37,51 and porosity 49,52−54 .…”