Laser Welding Process – A Review of Keyhole Welding Modelling

Svenungsson, Josefine; Choquet, Isabelle; Kaplan, Alexander

doi:10.1016/j.phpro.2015.11.042

Cited by 126 publications

(82 citation statements)

References 44 publications

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“…The energy densities applied below 50 J/ mm 3 show a significant amount of porosity due to insufficient melting of the powder particles, which could be conceived from the shape of the porosity and presence of sintered un-melted powder particles. The energy densities applied higher than 66 J/mm 3 also show some amount of porosity due to higher energy resulting in keyhole effects confirmed by the rounded shape of pores [9,11,19,20,22]. The red dotted region in the Fig.…”

Section: Resultsmentioning

confidence: 93%

“…For depth-to-width ratios around 0.37 to 0.6, it has at least 2-3 layers melted below and can ensure proper welding with the substrate. SLM can be considered very similar to laser welding, with high power levels and slow scan speeds, and a conduction mode similar to welding/deposition occurs, resulting in a deeper melt pool [11,16,19,20].…”

Section: Resultsmentioning

confidence: 99%

“…The formation of porosity in the deposits could be derived from the keyhole-shaped melt pool that developed while high power parameters were used. High energy density causes the alloy to melt and vaporize in some local regions; since the process is dynamic and quick, the vapors cannot escape fully and become entrapped in the melt pool, resulting in pores (which appear round) in the deposit [16,[19][20][21][22]. However, the pores when formed towards the top of the melt pool are not detrimental because re-melting causes gas to escape out of that layer during subsequent layer deposition.…”

Section: Resultsmentioning

confidence: 99%

“…However, the pores when formed towards the top of the melt pool are not detrimental because re-melting causes gas to escape out of that layer during subsequent layer deposition. The pores formed deep inside, and in the lower end of the melt pool, are more detrimental [9,11,15,19,22]. Therefore, higher power and lower speed should be avoided for overcoming such adverse defects.…”

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Influence of processing parameters on the evolution of melt pool, porosity, and microstructures in Ti-6Al-4V alloy parts fabricated by selective laser melting

Dilip

Zhang

Teng³

et al. 2017

Prog Addit Manuf

315

120

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Selective laser melting involves melting and solidification of metal powder particles in a track-by-track and layer-by-layer method to fabricate 3D parts. The present investigation focuses on understanding the effect of laser power and scan speed on the evolution of melt pool, porosity and multiple thermal cycling effects on the microstructure in parts fabricated using selective laser melting. In this study, Ti-6Al-4V pre-alloyed powder was used to produce single-track deposits and bulk parts. Using different combinations of laser power and scan speeds, single-track deposits and bulk parts were produced. The cross-sections of the single-track deposits and bulk samples were prepared for metallographic observations and the melt pool shape and size and porosity were evaluated. When a low energy density was applied the un-melted powder particles produced irregularly shaped porosity, and a high energy density resulted in rounded porosity, which was due to keyhole effects. The samples produced with a proper combination of power and speeds were fully dense. Further, microstructural development under the influence of process condition was highlighted. Overall, the study demonstrates a good correlation between the single-track melt pool geometries, porosity in bulk parts and also demonstrates the microstructural inhomogeneity during deposition.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Influence of processing parameters on the evolution of melt pool, porosity, and microstructures in Ti-6Al-4V alloy parts fabricated by selective laser melting

Dilip

Zhang

Teng³

et al. 2017

Prog Addit Manuf

315

120

View full text Add to dashboard Cite

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“…The laser beam can penetrate deeper into the material by means of this cavity and it is reflected multiple times on the keyhole walls, a part of it being absorbed at each contact with the walls. Thus, the multiple Fresnel absorption/reflection can significantly increase absorption efficiency for the laser radiation in a dynamic regime, and therefore the involved temperatures could be more elevated while event times could be shorter as compared to the static regime [28,29].…”

Section: Discussionmentioning

confidence: 99%

Control of Porosity and Spatter in Laser Welding of Thick AlMg5 Parts Using High-Speed Imaging and Optical Microscopy

Popescu

Delval

Leparoux

2017

Metals

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Abstract:We report on a feedback mechanism for rapid identification of optimal laser parameters during welding of AlMg5 coupons using real-time monitoring by high-speed imaging. The purpose was to constrain the liquid movement in the groove in order to obtain pore-free welds in this otherwise difficult-to-weld alloy. High-speed imaging of the welding process via an optical microscope allowed for recording at millimeter level, providing new information on liquid-metal dynamics during laser irradiation as well as plausible explanations for spatter occurrence and pores formation. The pore formation and especially the position of these pores had to be controlled in order to weld 3 mm thick samples. By tuning both laser power and pulse duration, pores were aligned on a single line, at the bottom of the weld. A laser pass of reduced power on that side was then sufficient for removing all pores and providing a suitable weld.

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