Experimental and numerical exploration of defocusing in Laser Powder Bed Fusion (LPBF) as an effective processing parameter

Liu, Binqi; Fang, Gang; Lei, Liping; Liu, Wei

doi:10.1016/j.optlastec.2022.107846

Cited by 19 publications

(4 citation statements)

References 29 publications

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“…Supplementary method 3) measurements were performed with similar beam sizes having an opposite defocusing position (positive and negative as divergent and convergent beams, respectively) and different laser intensity distribution. In conduction mode, the melt pool dimensions proved to be similar under identical laser processing parameters with a slight increase in melt pool depth and length in positive defocus, in agreement with previous observations 52,53 . Upon transition from conduction to keyhole, a signi cant difference in the melt pool length is observed with 45% higher values in RM2 compared to RM6.…”

Section: Operando Observation Of the Thermo-mechanical Instabilitiessupporting

confidence: 90%

Operando X-Ray imaging of stochastic inter-regime instabilities in laser melting processes: direct evidence of acoustic emission signatures

Nasab

Masinelli

Formanoir

et al. 2023

Preprint

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Laser powder bed fusion (LPBF) is a metal additive manufacturing technique involving complex interplays between vapor, liquid, and solid phases. Despite LPBF’s unprecedented capabilities compared to conventional manufacturing methods, the underlying physical phenomena can result in inter-regime instabilities followed by transitions between conduction and keyhole melting regimes — leading to defects. For the first time, we investigated these issues through operando synchrotron X-ray imaging synchronized with acoustic emission recording, during the remelting processes of LPBF-produced thin walls, monitoring regime changes occurring under constant laser processing parameters. The collected data show an increment in acoustic signal amplitude when switching from conduction to keyhole regime, which we correlated to changes in laser absorptivity. Moreover, a full correlation between X-ray imaging and the acoustic signals permitted the design of a simple filtering algorithm to predict the melting regimes. As a result, conduction, stable keyhole, and unstable keyhole regimes could be identified with a time resolution of 100 µs, even under rapid transitions, providing a straightforward method to accurately detect undesired processing regimes without the use of artificial intelligence.

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Section: Operando Observation Of the Thermo-mechanical Instabilitiessupporting

confidence: 90%

Operando X-Ray imaging of stochastic inter-regime instabilities in laser melting processes: direct evidence of acoustic emission signatures

Nasab

Masinelli

Formanoir

et al. 2023

Preprint

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“…54 Importantly, the application of a zero-focus offset was pivotal in order to fabricate HSLs with the thinnest walls possible by LPBF. 55 After fabrication, the lattice specimens were cooled in the powder bed to room temperature.…”

Section: Methodsmentioning

confidence: 99%

AlSi10Mg hollow-strut lattice metamaterials by laser powder bed fusion

Noronha,

Leary,

Brandt

et al. 2024

Mater. Adv.

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“…Many researchers are implementing numerical simulations to study heat transfer and fluid flow during the SLM process across a variety of materials. They especially focus on single-track laser melting models, considering process parameters such as laser power, scanning speed, and layer thickness [5][6][7][8][9][10][11][12]. Additionally, some researchers extend their simulations to multi-track and multi-layer SLM processes to investigate further process parameters, including scanning patterns and hatch spacing.…”

Section: Introductionmentioning

confidence: 99%

Effect of hatch spacing in selective laser melting process of Ti-6Al-4V alloy on finished surface roughness: A computational study

THONGPRON,

NINPETCH,

CHALERMKARNNON

et al. 2024

J Met Mater Miner

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The Selective Laser Melting (SLM) process is a promising additive manufacturing technology for producing complex metal parts. However, this process has certain limitations, including lack of fusion and defects, which can hinder its industrial applications. These challenges can be addressed by determining the appropriate overlap percentage parameters. This study used numerical simulation to explore the effect of overlap percentage on multi-track melting in the SLM process for Ti-6Al-4V. The simulation results categorize the multi-track melting morphologies into two distinct groups. The first group, (0% to 40% overlap), displays consistent surface roughness with an average Ra value of 7 µm. In contrast, the second group (50% to 60% overlap), shows non-uniform shapes. Specifically, the three central tracks in this group present an Ra value of approximately 4 µm. However, when all five tracks of this group are taken into account, the average Ra rises to 14 µm. These differences in surface roughness can be attributed to factors like energy density and the Marangoni effect. Both melt pool depth and shrinkage depth in the overlap area are significant as they might contribute to the risk of the lack of fusion defects. The insights from this research hold potential in shaping scanning pattern strategy design.

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Experimental and numerical exploration of defocusing in Laser Powder Bed Fusion (LPBF) as an effective processing parameter

Cited by 19 publications

References 29 publications

Operando X-Ray imaging of stochastic inter-regime instabilities in laser melting processes: direct evidence of acoustic emission signatures

Operando X-Ray imaging of stochastic inter-regime instabilities in laser melting processes: direct evidence of acoustic emission signatures

AlSi10Mg hollow-strut lattice metamaterials by laser powder bed fusion

Effect of hatch spacing in selective laser melting process of Ti-6Al-4V alloy on finished surface roughness: A computational study

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