Feedstock powder processing research needs for additive manufacturing development

Anderson, Iver E.; White, Emma; Dehoff, Ryan R.

doi:10.1016/j.cossms.2018.01.002

Cited by 182 publications

(58 citation statements)

References 12 publications

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“…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].…”

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confidence: 99%

“…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].…”

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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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confidence: 99%

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confidence: 99%

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

Santecchia

Spigarelli

Cabibbo

2020

Metals

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“…Depending on the processing conditions, different other powder morphologies can be obtained (like irregular, satellite, "splat cap", elongated, broken, agglomerated etc.) [1][2][3][4][5][6]. Smooth spherical powders are the most desired for AM processes because they ensure a better flowability compared to other morphologies, a higher flow rate is achieved by a reduced inter-particular friction and low risk of mechanical interlocking [6].…”

Section: Introductionmentioning

confidence: 99%

Characterization of IN 625 recycled metal powder used for selective laser melting

2020

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Additive manufacturing of high-quality materials by Selective Laser Melting depends not only on establishing appropriate process parameters, but also on the characteristics of the metal powders used and their stability over time or after recycling. The aim of the research was to characterize the IN 625 powder used over multiple manufacturing cycles with a Lasertec 30 SLM machine. In order to achieve the research's goal, virgin and recirculated powder's physical and technological characteristics were investigated. A decrease in all D-values (D10, D50, D90) of the powder size distribution was observed after multiple recirculation cycles showing a decrease of the powder dimensional range over time. Both virgin and recirculated powders are composed of mainly spherical particles, but elongated particles and satellite particles were observed as well. The dimensional evolution analysis showed a deviation from the powder ideal roundness, deviation that is more pronounced over multiple recirculation cycles. It was experimentally determined that the powders present a good flowability based on the flow rate value obtained for both virgin and recirculated powders, confirmed also by the Hausner ratio and angle of repose.

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“…There exists a significant body of literature detailing various instabilities that occur during close-coupled gas atomization and how these may impact on the application of such powders as ALM feedstock (see e.g. the recent review by (Anderson et al, 2018)). The corollary of this is the prospect that if the stability of the atomization process could be improved, then a superior powder produce could be offered.…”

Section: Introductionmentioning

confidence: 99%

The Physical Mechanism Formelt Pulsation During Close-Coupled Atomization

Mullis

2019

Atomiz Spr

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High speed filming (18000 fps) has been used to study the phenomenon of melt pulsation in a discrete jet, high pressure gas atomization system. Image processing routines have been developed to determine the velocity of material within the melt plume as it streams away from the melt delivery nozzle and to parameterise the shape of the melt plume. This data is then correlated with the volume of material in the melt plume, which is used as a diagnostic for melt pulsation. We find that during periods of low melt the constriction in the melt plume in which its diameter is a minimum is smaller and further downstream. Both appear to be consistent with a transition from an open-wake structure during periods of high melt flow to a closed-wake during periods of low melt flow. Moreover, the average velocity of material in the plume appears to drop during periods of low melt flow, which we ascribe to its passage through the Mach disk. We conclude that there is sufficient evidence to assert that the closed-wake condition survives the introduction of a dense second fluid to the atomizer and that alternation between the open-and closed-wake condition is the likely cause of the observed melt pulsation.

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Feedstock powder processing research needs for additive manufacturing development

Cited by 182 publications

References 12 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

Characterization of IN 625 recycled metal powder used for selective laser melting

The Physical Mechanism Formelt Pulsation During Close-Coupled Atomization

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