Influence of processing and microstructure on the local and bulk thermal conductivity of selective laser melted 316L stainless steel

Simmons, Jacob C.; Chen, Xiaobo; Azizi, Arad; Daeumer, Matthias A.; Zavalij, Peter Y.; Zhou, Guangwen; Schiffres, Scott N.

doi:10.1016/j.addma.2019.100996

Cited by 54 publications

(41 citation statements)

References 43 publications

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“…4 ). A simple scaling law defines a two-dimensional (2D) pattern that retains descriptive capabilities for porosity data collected from six independent studies 6 , 21 , 28 – 31 spanning ten process parameter sets and material properties. This scaling law is expressed as where describes the volume fraction of the porosity.…”

Section: Resultsmentioning

confidence: 99%

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

et al. 2021

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Metal three-dimensional (3D) printing includes a vast number of operation and material parameters with complex dependencies, which significantly complicates process optimization, materials development, and real-time monitoring and control. We leverage ultrahigh-speed synchrotron X-ray imaging and high-fidelity multiphysics modeling to identify simple yet universal scaling laws for keyhole stability and porosity in metal 3D printing. The laws apply broadly and remain accurate for different materials, processing conditions, and printing machines. We define a dimensionless number, the Keyhole number, to predict aspect ratio of a keyhole and the morphological transition from stable at low Keyhole number to chaotic at high Keyhole number. Furthermore, we discover inherent correlation between keyhole stability and porosity formation in metal 3D printing. By reducing the dimensions of the formulation of these challenging problems, the compact scaling laws will aid process optimization and defect elimination during metal 3D printing, and potentially lead to a quantitative predictive framework.

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Section: Resultsmentioning

confidence: 99%

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

et al. 2021

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“…In addition, Hajnys et al [37], Liu et al [40], and Benson et al [41] explained that a wide PSD with a mix of large and fine particle sizes can improve the packing density of the powder bed through the accumulation of the fine powders within the interstitial spaces that exist around the larger powder particles. However, some studies have also shown slightly reduced flowability when a wide PSD is used for AM fabrication due to increased inter-particle friction, thereby suggesting that some compromise is needed when selecting the particle sizes to attain the highest possible packing density while maximizing flowability [42][43][44]. On the other hand, several researchers recommend different nominal powder particle sizes to be used as the starting feedstock for L-PBF AM processes, e.g., 10-60 [28], 10-45 [29], and 5-80 µm [45].…”

Section: Introductionmentioning

confidence: 99%

Comparison between Virgin and Recycled 316L SS and AlSi10Mg Powders Used for Laser Powder Bed Fusion Additive Manufacturing

Yusuf

Choo

Gao

2020

Metals

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In this study, the comparison of properties between fresh (virgin) and used (recycled) 316L stainless steel (316L SS) and AlSi10Mg powders for the laser powder bed fusion additive manufacturing (L-PBF AM) process has been investigated in detail. Scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) techniques are used to determine and evaluate the evolution of morphology, particle size distribution (PSD), circularity, chemical composition, and phase (crystal structure) in the virgin and recycled powders of both materials. The results indicate that both recycled powders increase the average particle sizes and shift the PSD to higher values, compared with their virgin powders. The recycled 316L SS powder particles largely retain their spherical and near-spherical morphologies, whereas more irregularly shaped morphologies are observed for the recycled AlSi10Mg counterpart. The average circularity of recycled 316L SS powder only reduces by ~2%, but decreases ~17% for the recycled AlSi10Mg powder. EDX analysis confirms that both recycled powders retain their alloy-specific chemical compositions, but with increased oxygen content. XRD spectra peak analysis suggests that there are no phase change and no presence of any undesired precipitates in both recycled powders. Based on qualitative comparative analysis between the current results and from various available literature, the reuse of both recycled powders is acceptable up to 30 times, but re-evaluation through physical and chemical characterizations of the powders is advised, if they are to be subjected for further reuse.

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“…(C) 2D scaling law combining both lack-of-fusion and keyhole porosity. Methods of measuring the porosity and computing error bars are provided in the literature (6,17,(24)(25)(26)(27). This reduced function space is much more easily visualized and interpreted than the original high-dimensional problem in which the porosity is controlled by 10 parameters.…”

Section: The Scaling Parameter Ke M L Dmentioning

confidence: 99%

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

Gan¹,

Kafka²,

Parab

et al. 2020

Preprint

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We leverage ultrahigh-speed synchrotron x-ray imaging and high-fidelity multiphysics modeling to identify strikingly simple yet universal scaling laws for keyhole stability and porosity in metal three-dimensional (3D) printing. The laws apply broadly and remain accurate for different materials, processing conditions, and printing machines. We define a new dimensionless number, the Keyhole number, to predict aspect ratio of a keyhole and the morphological transition from stable at low Keyhole number to chaotic at high Keyhole number. Furthermore, we discover inherent correlation between keyhole stability and porosity formation in metal 3D printing. By reducing the dimensions of the formulation of these challenging problems, the compact scaling laws will aid process optimization and defect elimination during metal 3D printing, and potentially lead to a quantitative predictive framework.

show abstract

Influence of processing and microstructure on the local and bulk thermal conductivity of selective laser melted 316L stainless steel

Cited by 54 publications

References 43 publications

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

Comparison between Virgin and Recycled 316L SS and AlSi10Mg Powders Used for Laser Powder Bed Fusion Additive Manufacturing

Universal scaling laws of keyhole stability and porosity in 3D printing of metals

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