Vapor–plasma plume investigation during high-power fiber laser welding

Shcheglov, P.Yu.; Gumenyuk, Andrey; Gornushkin, Igor B.; Rethmeier, Michael; Petrovskiy, V N

doi:10.1088/1054-660x/23/1/016001

Cited by 75 publications

(37 citation statements)

References 26 publications

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“…The laser powder bed fusion process is always performed under inert atmosphere, in order to avoid any possible interaction between the metal particles (very reactive with a high specific surface area) and impurities such as humidity and light elements (i.e., oxygen, carbon oxides), which might affect the local chemical composition and the resulting mechanical properties of the manufactured parts [18,23,58]. Furthermore, a continuous flow of inert gas is essential in order to limit the redeposition on the powder bed of by-products during the process; this is crucial because should the removal of by-products by the shielding gas flow not be effective, there is a high risk of laser attenuation [97][98][99].…”

Section: Shielding Gas Flowmentioning

confidence: 99%

“…It must be pointed out that, if a large amount of condensate is generated and eventually redeposited on the bed together with the ejected (spatter) particles, the surface properties of the powder will change and might influence the flowability of the reused feedstock material [101,135,136]. From Figure 10, it is possible to observe that condensate is in the form of nanoparticles since, during the cooling, there is a decrease in metal vapor solubility in the process chamber environment, giving rise to a supersaturated solution with high undercooling, a condition which fosters the formation of nanoparticles [39,97,98,126,137]. These results suggest that the reuse of powders with condensate content should be prevented, but more studies specifically focused on this topic are needed in order to monitor the condensate formation and evolution for different alloys.…”

Section: Condensatementioning

confidence: 99%

“…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].…”

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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: Condensatementioning

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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“…Meanwhile, the slender plume is created by the shining particles as the laser beam heats them during high-power fiber laser welding [28]. According to the experimental results shown in Fig.…”

Section: Analysis and Discussionmentioning

confidence: 99%

Effects of a paraxial TIG arc on high-power fiber laser welding

Zou

Xiao

et al. 2015

Materials & Design

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“…Shcheglov et al [12] observed two characteristic parts of the plume when laser welding mild steel (Fig. 1).…”

Section: Introductionmentioning

confidence: 95%

Impact of fume particles in the keyhole vapour

Volpp

2019

Appl. Phys. A

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During laser material processing, the energy of the laser beam needs to be efficiently and constantly transported to the processing zone to guarantee constant processing. However, spatters or ejected particles from the keyhole can absorb and scatter the laser energy leading to inhomogeneous heat input and can initiate defect occurrence like pore formation. The impact of ejected particles from the keyhole on the energy transport of the laser beam is not completely understood since they are difficult to observe due to the small size and high speeds of the ejections. In this work, the particle characteristics were derived from a simulation of the keyhole wall movement. The behavior of the calculated particles in a side shielding gas jet was calculated to derive the height, at which the particles leave the laser beam and are not interrupting the laser energy transfer to the processing zone. Low impulse values of the particles were calculated e.g., at defocusing positions slightly underneath the material surface, where also highest melt pool sizes were found. These observations indicate that the fume particles can be one reason to limit the energy delivery. An efficiency increase can be achieved by adjusting the keyhole parameters to a more stable keyhole.

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Vapor–plasma plume investigation during high-power fiber laser welding

Cited by 75 publications

References 26 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

Effects of a paraxial TIG arc on high-power fiber laser welding

Impact of fume particles in the keyhole vapour

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