Investigation of the laser–powder–atmosphere interaction zone during the selective laser melting process

Masmoudi, Amal; Bolot, Rodolphe; Coddet, Christian

doi:10.1016/j.jmatprotec.2015.05.008

Cited by 115 publications

(57 citation statements)

References 17 publications

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“…Such videos clearly reveal a lateral powder flow toward the melt-pool, which seems to be restricted to the hotter MP zone coincident to a vertical vapor flow. 12 Consequently, and in full agreement with Ref. 6, it can be assumed that the inward motion of powder particles toward the MP is directly provoked by the vapor flow.…”

Section: Discussionsupporting

confidence: 79%

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

Gunenthiram¹,

Peyre²,

Schneider³

et al. 2017

Journal of Laser Applications

140

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The laser powder bed fusion (LPBF) or powder-bed additive layer manufacturing process is now recognized as a high-potential manufacturing process for complex metallic parts. However, many technical issues are still to overcome for making LPBF a fully viable manufacturing process. This is the case of surface finish and the systematic occurrence of porosities, which require postmachining steps. Up till now, the porosity origin remains unclear but is expected to be related to the stability of the process. As a LPBF part is made by the accumulation of hundreds of meters of small weld beads, it also appears to be important to understand all the phenomena that occur during the laser-powder-melt pool (MP) interaction for each single track. For this reason, in the first part of our study, using an instrumented LPBF setup and a fast camera analysis (>10 000 image/s), single tracks were fabricated and analyzed in real time and postmortem. Spatters ejections and powder denudation phenomena were observed together with variations of melt pool dimensions and meltpool instabilities. In turn, the physical origin of this powder denudation and the dynamics of the MP were investigated and discussed.

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Section: Discussionsupporting

confidence: 79%

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

Gunenthiram¹,

Peyre²,

Schneider³

et al. 2017

Journal of Laser Applications

140

View full text Add to dashboard Cite

show abstract

“…The higher temperatures reached in the melt pool are inferred from an increase in vaporisation temperature of the metal at higher pressure and a reduction in energy loss via evaporation. The Clausius-Clapeyron equation describes the coexistence curve on the phase diagram for vaporisation of a material, for which the liquid and vapour phases exist in thermodynamic equilibrium [5,12,13]. For stainless steel 316 L, an empirical fit to experimental data in the range 1750 to 5000 K plot is given by [14,15]:…”

Section: Discussionmentioning

confidence: 99%

Laser powder bed fusion in high-pressure atmospheres

Bidare

Bitharas

Ward

et al. 2018

Int J Adv Manuf Technol

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High-speed imaging and schlieren imaging were used to investigate the interaction of the laser beam with the powder bed at pressures up to 5 bar, in argon and helium atmospheres. The entrainment of powder particles in the flow of shielding gas generated by the laser plume, and hence denudation, was reduced at high pressure for both gases. However, for argon, high pressure increased the temperature of both the melt pool and the laser plume, which significantly increased the generation of spatter and ionisation of the metal vapour with degraded surface smoothness and continuity. For helium, the formation of spatter and plasma did not increase with the increase in pressure above that observed at atmospheric pressure: its higher thermal conductivity and thermal diffusivity limited the laser plume temperature. Layers built at 5 bar in helium had a surface smoothness and continuity comparable to those built in argon at atmospheric pressure, but achieved at a higher laser scan speed, suggesting that a high-pressure helium atmosphere may be used to enhance the build rate.

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“…However, a possible correlation between MP instabilities and spatter formation was not fully addressed. Masmoudi et al (2015) also investigated the influence of surrounding atmosphere on the stability and shape of SLM melt-pools. They carried out a simplified modeling of vapor plume expansion at ambient and low pressure, and indicated that working under work pressure (like EBM) was not beneficial for the stability of SLM beads, due to excessive vaporization effects.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of spatter generation and melt-pool behavior during the powder bed laser beam melting process

Gunenthiram

Peyre

Schneider

et al. 2018

Journal of Materials Processing Technology

276

120

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. A B S T R A C TThe experimental analysis of spatter formation was carried out on an instrumented SLM set-up allowing the quantification of spatter ejections and possible correlation with melt-pool behavior. Considering nearly similar SLM conditions than those carried out on SLM machines, an increase of large spatters (> 80 μm) with volume energy density (VED) was clearly demonstrated on a 316L stainless steel, which was attributed to the recoil pressure applied on the melt-pool by the metal vaporization and the resulting high velocity vapor plume. In a second step, much lower spattering was shown on Al-12Si powder beds than on 316L ones. Fast camera analysis of powder beds indicated that droplet formation was mostly initiated in the powder-bed near the melt-pool interface. On Al-12 Si alloys, such droplets were directly incorporated in the MP without being ejected upwards as spatters like on 316L. Last, it was shown that a strong reduction of spattering was possible even on 316L, with the use of low VED combined with larger spots (≈0.5 mm), allowing to melt sufficiently deep layers in conduction regime and ensure adequate dilution between layers.

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Investigation of the laser–powder–atmosphere interaction zone during the selective laser melting process

Cited by 115 publications

References 17 publications

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

Laser powder bed fusion in high-pressure atmospheres

Experimental analysis of spatter generation and melt-pool behavior during the powder bed laser beam melting process

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