Characterization of laser spatter and condensate generated during the selective laser melting of 304L stainless steel powder

Sutton, Austin T.; Kriewall, Caitlin S.; Leu, Ming-Chuan; Newkirk, Joseph William; Brown, Ben

doi:10.1016/j.addma.2019.100904

Cited by 42 publications

(58 citation statements)

References 41 publications

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“…These effects were particularly studied by Grünberger and Domröse [100], who generated the so-called splashy process by changing the focal position of the laser and concluded that a proper gas flow rate is mandatory in order to avoid the occurrence of this phenomenon, since, in areas of the build chamber where the local gas flow velocity is slow, there is a higher beam scattering. The gas flow in the process chamber was found to be a crucial parameter to limit the presence of defects in parts obtained by laser powder bed fusion [97,101].…”

Section: Shielding Gas Flowmentioning

confidence: 99%

“…Spatters are typically emitted from the melt pool, where the surface tension generates particles with unique and non-uniform chemical compositions [128]. Looking at all the possible shapes collected in different papers addressing spatter particles, Sutton et al [101] suggested the following potential classification based on the morphology:…”

Section: Spattermentioning

confidence: 99%

“…Spatter particles are likely to appear to have a wide size distribution range which depends strongly on the laser power (small power produces small spatters and vice versa [33]), which goes from highly coarse particles (larger than 100 µm), down to particles having diameters within the typical LPBF size distribution (10-45 µm) as demonstrated by several authors [83,101,129,130], which could be the majority of the ejections (even up to 90% [101]) of heat-affected powder and spatter in particular. Therefore, the latter will not be cut out by sieving the metal powder feedstock before reuse and might alter the local chemical composition of the parts to be built, as well as influencing the metal vapor formation, and the further generation and redeposition of condensate material.…”

mentioning

confidence: 96%

mentioning

confidence: 99%

“…A gradual coarsening of reused powders was observed for different metal powder alloys, such as 304L [101], Inconel 718 [19], and Ti64 [79]. Possible reasons behind this behavior could be the size segregation during the spreading process and the fact that smaller particles are more likely to be entrained in the fluid flow induced by the laser-powder interaction [78,101]. Furthermore, it is worth noting that the amount of spatter generated can vary even if process parameters are kept constant, owing to the partial absorption and scattering of the laser radiation given by the metal vapor plume, in a way similar to what happens during laser welding [98,119,121,126,131].…”

mentioning

confidence: 99%

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Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Santecchia

Spigarelli

Cabibbo

2020

Metals

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Metal additive manufacturing is changing the way in which engineers and designers model the production of three-dimensional (3D) objects, with rapid growth seen in recent years. Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. To make LPBF more cost-efficient and environmentally friendly, it is of paramount importance to recycle (reuse) the unfused powder from a build job. However, since the laser-powder interaction involves complex physics phenomena and generates by-products which might affect the integrity of the feedstock and the final build part, a better understanding of the overall process should be attained. The present review paper is focused on the clarification of the interaction between laser and metal powder, with a strong focus on its side effects. Figure 1. Schematics of the laser powder bed fusion (LPBF) equipment. Adapted from Reference [9] with permission from Elsevier.While the market and the applications of laser powder bed fusion continuously and impressively grew in recent years, there is a common view across users and researchers concerning the repeatability of the process in terms of chemical composition and mechanical properties of the final parts, which are of paramount importance when challenging environmental or testing conditions are considered [10][11][12][13][14][15][16].The most typical approach to study the microstructural and mechanical properties of parts built by LPBF is to compare them with castings of the same alloy or, rather, the corresponding alloy since the starting material is metal powder rather than a fuse. However, in some existing alloys designed for cast and wrought parts, laser additive manufacturing processing results in cracking or other microstructure deficiencies [11,12,16,17]. It is worth noting that LPBF has more similarities with laser welding rather than casting, since the two laser-based techniques have some common features (i.e., melt-pool formation, moving heat source) [18]. However, process parameters are, in general, quite different in terms of laser power and scan speed, and the laser-matter interaction is much more complicated in LPBF processes, since the powder feedstock is inherently unstable and the solidified material undergoes multiple thermal cycles corresponding to the fusion of subsequent layers during the additive process [19][20][21][22]. Furthermore, owing to the similarities with welding and to the complicated interaction between laser and metal particles, when comparing laser powder bed fusion with other metal forming processes, it is evident that the range of processable alloys is very limited and the number of high-productivity commercially available alloys is even smaller [23]. One of the reasons behind this is that the level of metal powder sensitivity to the laser action during LPBF is not yet fully understood, despite the efforts of the scientific community to uncover it [24][25][26][27], and ...

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Section: Shielding Gas Flowmentioning

confidence: 99%

Section: Spattermentioning

confidence: 99%

mentioning

confidence: 96%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Santecchia

Spigarelli

Cabibbo

2020

Metals

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Evaluation of the role of hatch-spacing variation in a lack-of-fusion defect prediction criterion for laser-based powder bed fusion processes

Harkin

Wu²,

Nikam³

et al. 2023

Int J Adv Manuf Technol

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Lack of fusion (LOF) defects impact adversely on the mechanical properties of additively manufactured components produced via laser-based powder bed fusion. Following a stress-relieving heat treatment, the tensile properties and hardness of Ti6Al4V components were found to be negatively impacted by the presence of LOF defects. This work considers a geometrical-based inequality for the prediction of LOF defects. We critically evaluate an LOF criterion using both the experimentally and analytically obtained melt pool geometries. Experimentally, we determined melt pool dimensions by analysing a single-layer, multi-track deposition with oversized hatch spacing in order to establish depth and width from non-overlapping melt pools. Analytically, Rosenthal-based predictions of melt pool size (width and depth) are applied. To investigate LOF defects, we used hatch spacing as the main parameter variation to investigate defects while keeping all other controllable parameters unchanged. An original LOF criterion from the literature was found to be an adequate predictor of LOF defects when experimentally obtained melt pool geometry was used. Critically, however, the analytical expressions for melt pool geometry were found to be in error and this caused the LOF criterion to fail in predicting LOF defects in all cases where defects were observed experimentally. However, an adaptation to the LOF prediction criterion is proposed whereby it is recommended that a correction factor $${R}_{c}^{2}=0.7$$ R c 2 = 0.7 (or $${R}_{c}=0.83$$ R c = 0.83 ) is used with the analytically derived melt pool geometry. Furthermore, this correction is extended into the laser power versus scanning speed operating space to give minimum (corrected) line energy for LOF avoidance in Ti6Al4V components.

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Monitoring melted state of reinforced particle in metal matrix composite fabricated by laser melt injection using optical camera

Huang

2023

Int J Adv Manuf Technol

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Characterization of laser spatter and condensate generated during the selective laser melting of 304L stainless steel powder

Cited by 42 publications

References 41 publications

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Evaluation of the role of hatch-spacing variation in a lack-of-fusion defect prediction criterion for laser-based powder bed fusion processes

Monitoring melted state of reinforced particle in metal matrix composite fabricated by laser melt injection using optical camera

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