Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing

Ly, Sonny; Rubenchik, Alexander M.; Khairallah, Saad A.; Guss, Gabe; Matthews, Manyalibo J.

doi:10.1038/s41598-017-04237-z

Cited by 383 publications

(207 citation statements)

References 36 publications

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“…13,14 Although the laser irradiates on the melt pool (liquid) and not on the powder bed during the SLM process, 15 the effective optical absorption could have improved due to the continuous incorporation of the oxidized copper powder particles from the denudation zone into the melt pool, offering a fresh and optically absorptive powder surface. 15,16 Figure 2A shows the evolution of the relative density of the parts as a function of the applied volumetric energy density for different input power levels in an argon and nitrogen atmosphere. It is clear that a laser power of 300 and 400 W is not sufficient to cause full melting of the copper powder, resulting in lower relative part density (below 93%).…”

Section: Methodsmentioning

confidence: 99%

Mechanical and electrical properties of selective laser‐melted parts produced from surface‐oxidized copper powder

Jadhav

Zhang

Kruth

et al. 2019

Mat Design & Process Comms

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Selective laser melting of pure copper is challenging because of its high optical reflectivity and thermal conductivity. Accordingly, the surface of pure copper powder was modified by oxidation to enhance the optical absorption. The powder with improved optical absorption facilitated the production of crack‐free and dense copper parts at relatively lower laser energy density in both argon and nitrogen atmosphere. The microstructural analysis demonstrated the presence of stable melt tracks without obvious porosity. A very high electrical conductivity of approximately 89% of the international annealed copper standard, the hardness of approximately 93 HV, a tensile strength of approximately 270 MPa, and ductility of approximately 28% were achieved in the as‐built condition.

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Section: Methodsmentioning

confidence: 99%

Mechanical and electrical properties of selective laser‐melted parts produced from surface‐oxidized copper powder

Jadhav

Zhang

Kruth

et al. 2019

Mat Design & Process Comms

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“…During LPBF, it is very common to see very bright ejections (sparks) leaving the laser-powder interaction area; the melt pool undergoes a high degree of superheat, leading to vaporization and material ejection [35,114,115]. Ly et al [35] reported recently that, while the dominant mechanism of denudation is vapor recoil pressure, the formation of ejections is mostly influenced by vapor-driven entrainment of micro-particles.…”

Section: Heat-affected Powdermentioning

confidence: 99%

“…The interaction between the high-energy laser typical of LPBF equipment and the metal powder bed can result in powder contamination through different phenomena including agglomeration, partial fusing, partial/full oxidation, metal vapor condensate, and generation of spatter [32][33][34][35][36][37][38][39][40]. These phenomena can alter not only the properties of the reused powder (i.e., flowability, chemical composition, tap density, particle size), but also the surface (i.e., roughness), microstructural (i.e., local variation of chemical composition, pore formation), and mechanical properties of the final part.…”

Section: Introductionmentioning

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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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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“…For these melt pool models, an appropriate powder-bed model should be employed. Modeling of the powder-bed has been done in two different ways: powder-scale (refer to [28][29][30][31][32][33][34][35]) and continuum-scale (refer to [36][37][38][39][40][41][42][43]). Although the first approach enables simulating the size variations and the local changes in the melt pool such as incomplete melting or formation of pores [28,29], it is computationally expensive such that it is almost impossible to use it for full-part simulation.…”

Section: Melt Pool Modeling Through Fem Based Thermal Modelingmentioning

confidence: 99%

Multivariate Calibration and Experimental Validation of a 3D Finite Element Thermal Model for Laser Powder Bed Fusion Metal Additive Manufacturing

Mahmoudi

Tapia

Karayagiz

et al. 2018

Integr Mater Manuf Innov

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Metal additive manufacturing (AM) typically suffers from high degree of variability in the properties/performance of the fabricated parts, particularly due to the lack of understanding and control over the physical mechanisms that govern microstructure formation during fabrication. This paper directly addresses an important problem in AM: the determination of the thermal history of the deposited material. Any attempts to link process to microstructure in AM would need to consider the thermal history of the material. In-situ monitoring only provides partial information and simulations may be necessary to have a comprehensive understanding of the thermo-physical conditions to which the deposited material is subjected. We address this in the present work through linking thermal models to experiments via a computationally efficient surrogate modeling approach based on multivariate Gaussian processes (MVGPs). The MVGPs are then used to calibrate the free parameters of the multi-physics models against experiments, sidestepping the use of prohibitively expensive Monte Carlo-based calibration. This framework thus makes it possible to efficiently evaluate the impact of varying process parameter inputs on the characteristics of the melt pool during AM. We demonstrate the framework on the calibration of a thermal model for Laser-Powder Bed Fusion AM of Ti-6Al-4V against experiments carried out over a wide window in the process parameter space. While this work deals with problems related to AM, its applicability is wider as the proposed framework could potentially be used in many other ICME-based problems where it is essential to link expensive computational materials science models to available experimental data.

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Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing

Cited by 383 publications

References 36 publications

Mechanical and electrical properties of selective laser‐melted parts produced from surface‐oxidized copper powder

Mechanical and electrical properties of selective laser‐melted parts produced from surface‐oxidized copper powder

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

Multivariate Calibration and Experimental Validation of a 3D Finite Element Thermal Model for Laser Powder Bed Fusion Metal Additive Manufacturing

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