Tailoring surface quality through mass and momentum transfer modeling using a volume of fluid method in selective laser melting of TiC/AlSi10Mg powder

Dai, Donghua; Gu, Dongdong

doi:10.1016/j.ijmachtools.2014.09.010

Cited by 211 publications

(62 citation statements)

References 28 publications

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“…Similarly, for a medium scanning velocity (1200 mm/s), the Ra decreases first with an increase in laser power from 50 W to 60 W. However, the roughness saturated before increasing again along with an increase in laser power between 70 W and 100 W. is difference in behavior with 1200 mm/s can be attributed to the reduction in the lifetime of the molten pool and the fluid flow strength while the scanning velocity increases from 400 mm/s to 1200 mm/s. If the fluid flow strength is insufficient to overcome the viscous drag, there will be inefficient spreading of the molten pool, followed by a formation of surface asperities [18]. When the laser power increases, the melted powder volume increases, resulting in a greater demand for the flow driving forces and lifetime of the molten pool.…”

Section: Resultsmentioning

confidence: 99%

Formation of SS316L Single Tracks in Micro Selective Laser Melting: Surface, Geometry, and Defects

Castagne

Song

et al. 2019

Advances in Materials Science and Engineering

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To fabricate complex parts with a fine resolution and smooth finish, micro selective laser melting (SLM) has been developed recently by combining three attributes: small laser beam spot, fine powder size, and thin layer thickness. This paper studies the effect of the micro-SLM process parameters on the single track formation of 316L stainless steel. The surface morphology, geometrical features, and defects have been analyzed in detail. The results highlight that laser power and scanning velocity have a significant effect on the formation of single tracks. The single tracks fabricated through micro-SLM with varying process parameters are classified into four types: no melting, discontinuous, continuous but unstable, and continuous tracks. Besides, the top surface of the tracks is observed with “double-crest” morphology, due to the high recoil pressure gradient generated by the extremely fine spot size. In addition, molten pool geometry (width, depth, and height) has been characterized to study the mode of the molten pool in micro-SLM. Finally, the occurrence of two typical defects within the tracks, keyhole pore and cavity at the edges, has been studied.

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Section: Resultsmentioning

confidence: 99%

Formation of SS316L Single Tracks in Micro Selective Laser Melting: Surface, Geometry, and Defects

Castagne

Song

et al. 2019

Advances in Materials Science and Engineering

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“…However, the molten material in the center of the melt pool leans toward the back section (creating materials bump and stacks on the surface) after further increase of the P / v to 750 J m −1 (Figure c). Excessive increase of P / v to 1500 J m −1 causes a severe material evaporation and leads to an unsmooth, lowered and interrupted melt spread, forming discontinuous scan tracks, and surface balls (Figure d) …”

Section: Mmcs From Conventional Techniques To Powder Additive Manufacmentioning

confidence: 99%

“…Schematics of the change in the melting pool dynamics and the top surface morphologies during and after SLM of AlSi10Mg/TiC composite parts with increasing the energy density: a) P = 150 W, v = 400 mm s −1 , P/v = 375 J m −1 ; b) P = 150 W, v = 300 mm s −1 , P/v = 500 J m −1 ; c) P = 150 W, v = 200 mm s −1 , P/v = 750 J m −1 ; and d) P = 150 W, v = 100 mm s −1 , P/v = 1500 J m −1 , as adapted from ref. .…”

Section: Mmcs From Conventional Techniques To Powder Additive Manufacmentioning

confidence: 99%

Selective Laser Melting to Manufacture “In Situ” Metal Matrix Composites: A Review

et al. 2019

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After a brief introduction on selective laser melting (SLM) and "ex situ" manufacture of metal matrix composites (MMCs), this paper reviews the capacities and benefits of SLM to activate and control various "in situ" reactions during fabrication of 3D parts. It introduces several systems (such as etc.) used to manufacture Al-based, Ti-based, and steel-based "in situ" MMCs. Then, it illustrates the novel microstructural characteristics of these SLM-made "in situ" MMCs for different cases, as they may appear from nano-particles to nano-whiskers and dendritic reinforcements homogeneously distributed in a metal matrix. It also focuses on SLM associated "in situ" mechanisms, explaining how an "in situ" reaction propagates based on "decomposition, diffusion, and reformation" and how the growth mechanisms turn into different morphologies such as rounded particles, whiskers, or polygonal block shapes. The influence of various SLM parameters (such as energy density, laser power/speed, powder layer thickness, and the size of initial powder particles) and the SLM "in situ" challenges are also discussed.

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“…12 Whereas when considerably elevated LED of 22?5 kJ m 21 is applied, the maximum operating temperature in the molten pool is as high as 1834?8 K. The length of the molten pool exceeds the circumference, 24 resulting in the formation of the Plateau-Rayleigh instability. 18 Therefore, the melt tends to splash due to a high capillary instability of the melt in the overheating local regions. The typical metallurgical defect of the SLM process, ''balling'' effect, is likely to occur in this instance, thereby significantly influencing the thermodynamic and kinetic characteristics during the laser irradiation.…”

Section: Temperature Distributions In Molten Poolmentioning

confidence: 99%

Tailored reinforcement/matrix interface and thermodynamic mechanism during selective laser melting composites

Dai

2016

Materials Science and Technology

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The simulation of thermodynamic behaviours of reinforcing particles and reinforcement/matrix interface during selective laser melting of particle reinforced metal matrix composites was presented. The transition from powder to solid phase, the surface tension and the density change were taken into account. It showed that the operating temperature and the resultant turbulent intensity increased with increasing the applied linear energy density, giving rise to the high instability of the molten pool. The gravity and capillary forces play a crucial role in the rearrangement and the attendant distribution state of the reinforcing particles. The particle morphology and distribution state in the as processed parts were experimentally studied, which were in good agreement with the results predicted by simulation. List of symbolsA laser absorptivity of the powder B view factor C p specific heat at constant pressure/J kg 21 K 21 D p average diameter of the powder particles/m F body force, e.g. gravity and buoyancy forces/ N h species enthalpy h c convective heat transfer coefficient/ W m 22 K 21 h ref reference enthalpy H enthalpy of the material DH latent heat of the phase change k sur temperature coefficient of surface tension M s mass source/kg p pressure/N m 22 P laser power/W S H source item of the energy conservation equation t time/s T temperature/K T ' ambient temperature/K T p temperature of the powder particles/K T ref reference temperature/K V ! velocity vector/m s 21u,v,w velocity magnitude/m s 21 x,y,z coordinates/m a volume fraction of the gas phase a i volume fraction of each phase a p fraction of particles b thermal expansion coefficient c surface tension/kg m 21 e radiation emissivity k thermal conductivity of the powder bed/ W m 21 K 21 k s thermal conductivity of the solid/ W m 21 K 21 k eff effective thermal conductivity of liquidsolid-gas multiphases/W m 21 K 21 k f thermal conductivity of the fluid/ W m 21 K 21 k r thermal conductivity due to the radiation among particles/W m 21 K 21 m dynamic viscosity/Pa s r coupled density/kg m 23 r l base metal density/kg m 23 r T base metal density at temperature T/kg m 23 r p particle density/kg/m 3 s e Stefan-Boltzmann constant v radius of the Gaussian laser beam/m

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Tailoring surface quality through mass and momentum transfer modeling using a volume of fluid method in selective laser melting of TiC/AlSi10Mg powder

Cited by 211 publications

References 28 publications

Formation of SS316L Single Tracks in Micro Selective Laser Melting: Surface, Geometry, and Defects

Formation of SS316L Single Tracks in Micro Selective Laser Melting: Surface, Geometry, and Defects

Selective Laser Melting to Manufacture “In Situ” Metal Matrix Composites: A Review

Tailored reinforcement/matrix interface and thermodynamic mechanism during selective laser melting composites

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