Keyhole-induced porosities in Laser-based Powder Bed Fusion (L-PBF) of Ti6Al4V: High-fidelity modelling and experimental validation

Bayat, Mohamad; Thanki, Aditi; Mohanty, Sankhya; Witvrouw, Ann; Yang, Shoufeng; Thorborg, Jesper; Tiedje, Niels Skat; Hattel, Jesper Henri

doi:10.1016/j.addma.2019.100835

Cited by 185 publications

(149 citation statements)

References 41 publications

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“…As described later, the melt pool of Specimen_A formed in the keyhole mode, and the pores were generated besides the formation of the keyhole. 12) The lack-of-fusion-type irregular pores were not observed in any specimen, indicating that the input heat energies through laser irradiation were adequately strong. Figure 4 shows the crystallographic textures that evolved in the specimens.…”

Section: Resultsmentioning

confidence: 90%

Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting

Ishimoto

Ito

et al. 2020

ISIJ Int.

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Section: Resultsmentioning

confidence: 90%

Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting

Ishimoto

Ito

et al. 2020

ISIJ Int.

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“…They are of smaller sizes usually less than 100 microns with spherical morphology. The keyhole pores are irregular in shape, larger in size usually above 100 microns and are formed due to 'rapid solidification of the metal' with inadequate gap filling with the molten metal [15]. It can be observed from figures 6(a)-(e) that keyhole pores dominated in all the samples with very few or negligible metallurgical pores.…”

Section: Effect Of Scan Speed and Hatch Distance On Microstructural Pmentioning

confidence: 93%

“…Additive Manufacturing (AM) techniques are used by most industries today to manufacture complete functional complex geometries from a digital model by joining material in a layer by layer mode [14][15][16]. Selective Laser Melting (SLM) which is a major technique in additive manufacturing generates high-density 3D parts by selectively melting and fusing metallic powder [17].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the effect of processing parameters on densification, microstructure and hardness of selective laser melted 7075 aluminium alloy

Mbakaan²,

Barki

2020

Mater. Res. Express

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The 7075 aluminum alloy of the 7xxx series largely used for structures in modern aircraft has been successfully fabricated using selective laser melting (SLM) technology. The morphology of the initial 7075 aluminum alloy powders was characterized by a Zeiss Evo 50 Scanning electron microscope (SEM). Energy Dispersive x-ray (EDX) spectrometer attached to SEM was used as a tool to obtain the chemical composition of the powders. Processing parameters including scan speed, hatch distance and constant laser power (100 and 150 W) effect on densification, microstructure and hardness were investigated. The initial powder particles were found to be elongated and non-spherical and composed of Al, Zn, Mg, Cu, and Ag without Si. The result of the influence of processing parameters on properties of the as-built samples by SLM technology indicates that higher densification of parts can be gained using higher laser power and lower laser scan speed and hatch distance due to significant reduction in the number of pores. Two major types of pores including metallurgical and keyhole pores have been identified with the keyhole pores dominating the samples processed by low laser power of 100 W. The keyhole pores increase in size at a high scan speed and hatch distances. By using higher laser power of 150 W, the keyhole pores reduced significantly while metallurgical pores appear. The result of the hardness test conducted on the samples shows that high values of hardness can be achieved with low scan speed.

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“…However, with the range of melting parameters used in this work, we do not believe that we are in a keyhole regime. Indeed, the inspection of the 3D view of the various molten tracks does not reveal the presence of pores aligned along the molten track at a given depth as highlighted in references [33][34][35] for melting conditions leading to numerous keyhole pores. This was assessed even for the highest energy input (P = 150 W, v = 200 mm/s) expected to be the most sensitive to keyhole porosity.…”

Section: Building Walls Made Of Multiple Adjacent Melted Tracksmentioning

confidence: 99%

In situ 3D X-ray microtomography of laser-based powder-bed fusion (L-PBF)—A feasibility study

Lhuissier

Bataillon

Maestre

et al. 2020

Additive Manufacturing

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X-ray microtomography can be used to characterise objects undergoing fabrication by additive manufacturing. During the layer-by-layer building process, it can provide key information about geometry, roughness and it can even reveal typical defects such as lack-offusion porosity, gas pores or cracks. Usually, objects are built with varied processing parameters and then characterised post-mortem. In the present work, we describe our custom-designed additive manufacturing chamber allowing in situ 3D-non-destructive characterisation to be performed during layer-by-layer construction using synchrotron X-ray microtomography. Scans before (subsequently to powder deposition) and after local laser melting are acquired for every layer. A few examples of such a characterisation demonstrate the ability of the setup to reproduce conditions close to those used in conventional laser powder-bed fusion devices and to reveal key phenomena.

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Keyhole-induced porosities in Laser-based Powder Bed Fusion (L-PBF) of Ti6Al4V: High-fidelity modelling and experimental validation

Cited by 185 publications

References 41 publications

Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting

Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting

Experimental investigation of the effect of processing parameters on densification, microstructure and hardness of selective laser melted 7075 aluminium alloy

In situ 3D X-ray microtomography of laser-based powder-bed fusion (L-PBF)—A feasibility study

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