Investigation of the microstructure and surface morphology of a Ti6Al4V plate fabricated by vacuum selective laser melting

Sato, Yuji; Tsukamoto, Masahiro; Masuno, Shinichiro; Yamashita, Yorihiro; Yamashita, Kensuke; Tanigawa, Daichi; Abe, Nobuyuki

doi:10.1007/s00339-016-9996-8

Cited by 37 publications

(7 citation statements)

References 15 publications

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“…One of these influencing factors is the process pressure. Lowering the process pressure is widely accepted to be beneficial for laser welding [4], a process closely related to LPBF, but has rarely been investigated for LPBF except for a few studies [5][6][7][8][9][10][11][12][13][14].…”

Section: State Of the Artmentioning

confidence: 99%

Vacuum laser powder bed fusion—track consolidation, powder denudation, and future potential

Kaserer

Bergmueller

Braun

et al. 2020

Int J Adv Manuf Technol

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Defects in parts processed by laser powder bed fusion (LPBF) are often triggered by laser/plasma plume interference and spattering. The implementation of a LPBF process in vacuum has been suggested to possibly reduce these effects. Within this study, the effects of process pressure variations between 1 mbar and atmospheric pressure on the generation of single tracks and on the surrounding layer of loose powder particles were studied for CP titanium grade 2 and the Maraging steel 1.2709. Below 10 mbar no single tracks could be generated and the powder layer adjacent to the track was effectively denuded. It was found that the essential mechanism for incorporating powder into the melt pool begins to work at process pressures above 10 mbar and its effectiveness increases with increasing pressure. The amount of powder incorporated into the melt pool depends on the material and the scanning conditions. With identical scanning conditions, this amount of powder is significantly larger for titanium than for steel. For process pressures above 200 mbar, no significant change in the amount of spattering could be found. In this pressure range improved process stability could be possible due to a reduced laser/plasma interaction and an increased laser penetration depth.

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Section: State Of the Artmentioning

confidence: 99%

Vacuum laser powder bed fusion—track consolidation, powder denudation, and future potential

Kaserer

Bergmueller

Braun

et al. 2020

Int J Adv Manuf Technol

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“…where n i and m i are the components of outward facing normal to ∂V lat and ∂V top , respectively and the repeated index implies summation over i. During the SLM process the base plate is typically pre-heated, and stays at this constant temperature [34,35]. We take this into account by prescribing a temperature boundary condition on the bottom surface ∂V bot that is bonded to the base plate as…”

Section: Model Descriptionmentioning

confidence: 99%

A semi-analytical thermal modelling approach for selective laser melting

Yang

Knol

Keulen

et al. 2018

Additive Manufacturing

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Selective laser melting (SLM) wherein a metal part is built in a layer-by-layer manner in a powder bed is a promising and versatile way for manufacturing components with complex geometry. However, components built by SLM suffer from substantial deformation of the part and residual stresses. Residual stresses arise due to temperature gradients inherent to the process and the accompanying deformation. It is well known that the SLM process parameters and the laser scanning strategy have a substantial effect on the temperature transients of the part and henceforth on the degree of deformations and residual stresses. In order to provide a tool to investigate this relation, a semi-analytical thermal model of the SLM process is presented which determines the temperature evolution in a 3D part by way of representing the moving laser spot with a finite number of point heat sources. The solution of the thermal problem is constructed from the superposition of analytical solutions for point sources which are known in semi-infinite space and complimentary numerical/analytical fields to impose the boundary conditions. The unique property of the formulation is that numerical discretisation of the problem domain is decoupled from the steep gradients in the temperature field associated with localised laser heat input. This enables accurate and numerically tractable simulation of the process. The predictions of this semi-analytical model are validated by experiments and the exact solution known for a simple thermal problem. Simulations for building a complete layer using two different scanning patterns and subsequently building of multiple layers with constant and rotating scanning patterns in successive layers are performed. The computational efficiency of the semi-analytical tool is assessed which demonstrates its potential to gain physical insight in the full SLM process with acceptable computational costs.

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“…[8][9][10][11][12][13][14][15] For example, Ti6Al4V bulk plates were fabricated using a single-mode fiber laser in vacuum atmosphere. 16) Raw powder particles with sizes of approximately 4 to 88 µm were used. Austenitic stainless steel with low carbon, mainly containing Fe, Ni, and Cr, was sintered to form 3D bulk structures using a continuous wave laser with a 1075 nm wavelength.…”

Section: Introductionmentioning

confidence: 99%

Ni-based composite microstructures fabricated by femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles

Tamura

Mizoshiri

Sakùrai

et al. 2017

Jpn. J. Appl. Phys.

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Ni-based composite micropatterns were fabricated by the femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles. A NiO/Cr mixed nanoparticle solution including ethylene glycol and polyvinylpyrrolidone was irradiated with focused femtosecond laser pulses. The X-ray diffraction spectra of the fabricated micropatterns indicated that NiO nanoparticles were well reduced under atmospheric conditions in the laser scanning speed range of 5–15 mm/s. In contrast, micropatterns including NiO were formed at a laser scanning speed of 1 mm/s, indicating that the reduced Ni was reoxidized by overheating. These results were supported by those of energy-dispersive X-ray spectrometry analysis and the electrical resistivity of the micropatterns. The compositions such as Ni, NiO, Cr2O3, and Ni–Cr in the fabricated micropatterns depended on laser scanning speed. The selective fabrication of a ferromagnetic free microgear from the substrate and an axis fixed on the substrate was demonstrated by controlling the laser scanning speed. The fabrication process for Ni-based composite microstructures is useful for the fabrication of ferromagnetic microdevices.

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Investigation of the microstructure and surface morphology of a Ti6Al4V plate fabricated by vacuum selective laser melting

Cited by 37 publications

References 15 publications

Vacuum laser powder bed fusion—track consolidation, powder denudation, and future potential

Vacuum laser powder bed fusion—track consolidation, powder denudation, and future potential

A semi-analytical thermal modelling approach for selective laser melting

Ni-based composite microstructures fabricated by femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles

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