In-situ detection of redeposited spatter and its influence on the formation of internal flaws in laser powder bed fusion

Schwerz, Claudia; Raza, Ahmad; Lei, Xiangyu; Nyborg, Lars; Hryha, Eduard; Wirdelius, Håkan

doi:10.1016/j.addma.2021.102370

Cited by 29 publications

(47 citation statements)

References 22 publications

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“…Therefore, particles have different tracks and deposition distances on both sides. It conforms to what Claudia Schwerz et al [17] observed with a highspeed camera. Besides, since spatters closer to the outlet in Fig.…”

Section: Spatter Deposition and Removal Study For Six Different Scann...supporting

confidence: 91%

Modeling and Simulation of the Effect of Scan Strategy on Spatter Movement in Laser Powder Bed Fusion

Cen¹,

Liu²,

Yan³

et al. 2022

Preprint

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Multi-laser powder layer bed fusion (M-LPBF) has wide application prospects in aerospace, biomedical and industrial fields, dramatially improving the efficency of LPBF. However, the spatter still weakens the quality of the built part. With different scanning strategies, spatter distributed in various printing locations may result in compromised processing. By far, in existing spatter models, spatters are assumed as fixed particle size or multiple fixed injection angles, which do not adapt well to the spatter injection from the melt pool. Therefore, spatter injection models with three different particles with 300 in 28µm, 500 in 55µm and 1300 in 114µm, three different initial velocities and three angle ranges are developed to simulate with gas flow under six different scanning strategies. In gas-solid coupling simulation, the spatter injection model as discrete phase and N2 as continuous phase are calculated through passing information together. Particles ejection are in line with the spatter observed by others with high speed camera. It shows that particles with average particles with 63 in 28µm, 116 in 55µm and 398 in 114µm desiposit on the base, respectively. Its removal rates out of base are 79.0%, 76.8% and 69.4%, respectively. Besides, particles in 114µm deposit more on the start side of the scanning tracks under the scanning strategy of perpendicular to gas flow than others. Most particles deposit closer to the oulet with counter gas flow. The result will provide an important reference value for M-LPBF in the way of optimizing scanning strategy to reduce the impact of spatters.

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Section: Spatter Deposition and Removal Study For Six Different Scann...supporting

confidence: 91%

Modeling and Simulation of the Effect of Scan Strategy on Spatter Movement in Laser Powder Bed Fusion

Cen¹,

Liu²,

Yan³

et al. 2022

Preprint

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“…The monitoring system utilized in this study, based on the acquisition of visible and infrared emissions by means of a photodiode installed onaxis, is not necessarily suited for the detection of these flaws. On the other hand, the signal intensities are proportional to the melt pool dimensions, and the signal dynamics characteristics relate to processing conditions known to generate spatter, which indicates that the monitoring system used can be employed to detect instabilities that can generate spatters and thereby stochastic flaws elsewhere in the build area [37].…”

Section: Discussionmentioning

confidence: 99%

Linking In Situ Melt Pool Monitoring to Melt Pool Size Distributions and Internal Flaws in Laser Powder Bed Fusion

Schwerz

Nyborg

2021

Metals

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In situ monitoring of the melt pools in laser powder bed fusion (LPBF) has enabled the elucidation of process phenomena. There has been an increasing interest in also using melt pool monitoring to identify process anomalies and control the quality of the manufactured parts. However, a better understanding of the variability of melt pools and the relation to the incidence of internal flaws are necessary to achieve this goal. This study aims to link distributions of melt pool dimensions to internal flaws and signal characteristics obtained from melt pool monitoring. A process mapping approach is employed in the manufacturing of Hastelloy X, comprising a vast portion of the process space. Ex situ measurements of melt pool dimensions and analysis of internal flaws are correlated to the signal obtained through in situ melt pool monitoring in the visible and near-infrared spectra. It is found that the variability in melt pool dimensions is related to the presence of internal flaws, but scatter in melt pool dimensions is not detectable by the monitoring system employed in this study. The signal intensities are proportional to melt pool dimensions, and the signal is increasingly dynamic following process conditions that increase the generation of spatter.

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Section: Effect Of Spatter On Powder Re-coatingmentioning

confidence: 94%

“…The voids remained after the scanning of the next layer, creating metallurgical defects, as illustrated in Figure 14c. Schwerz et al [82] found the presence of spatter particles of approximately 136 µm in the cross-section of the part, illustrating how particles significantly larger than the nominal layer thickness were incorporated into the material despite recoating, and in the process, large spatter bumps of particles can cause damage to the scraper, as shown in Figure 14d. In order to detect the distribution of the re-deposition of the spatters on the build area, a long-exposure near-infrared in situ monitoring associated with image analysis was employed to determine the exact locations using the EOS EOSTATE Exposure OT system [82].…”

Section: Effect Of Spatter On Powder Re-coatingmentioning

confidence: 94%

A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures

Yin

et al. 2022

Micromachines

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Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes more severe in the fabrication of large-sized parts during the multi-laser L-PBF process. Therefore, investigations of spatter generation and countermeasures have become more urgent. Although much research has provided insights into the melt pool, microstructure, and mechanical property, reviews of spatter in L-PBF are still limited. This work reviews the literature on the in situ detection, generation, effects, and countermeasures of spatter in L-PBF. It is expected to pave the way towards a novel generation of highly efficient and intelligent L-PBF systems.

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In-situ detection of redeposited spatter and its influence on the formation of internal flaws in laser powder bed fusion

Cited by 29 publications

References 22 publications

Modeling and Simulation of the Effect of Scan Strategy on Spatter Movement in Laser Powder Bed Fusion

Modeling and Simulation of the Effect of Scan Strategy on Spatter Movement in Laser Powder Bed Fusion

Linking In Situ Melt Pool Monitoring to Melt Pool Size Distributions and Internal Flaws in Laser Powder Bed Fusion

A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures

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