Experimental and Numerical Analysis of Gas Dynamics in the Keyhole During Laser Metal Welding

Tenner, Felix; Brock, Christian; Gürtler, Franz-Josef; Klämpfl, Florian; Schmidt, Michael

doi:10.1016/j.phpro.2014.08.050

Cited by 23 publications

(7 citation statements)

References 20 publications

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“…This may be related to the thickness of the plates where high power is needed to penetrate the whole plate. High power laser is connected to faster downward melt flows at the keyhole front wall [17,34] as molten humps having a complex topology [16,35], higher temperatures [36], and more vigorous vapor plume oscillations and velocities [14,37]. The latter case is very special.…”

Section: Discussion On Root Qualitymentioning

confidence: 99%

Root formation and metallurgical challenges in laser beam and laser-arc hybrid welding of thick structural steel

Bunaziv

Dørum

Nielsen

et al. 2021

Int J Adv Manuf Technol

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Single-pass laser beam welding (LBW) of steel components with wall thickness of > 10 mm is of high interest due to enhanced productivity. Deep penetration LBW provides excessive hardness and certain quality issues such as root humping in flat position, which is associated with disability of surface tension to sustain melt dropout. High hardness is associated with fast cooling rates and shortage of filler wire transportation to the root of the fusion zone. Use of laser-arc hybrid welding (LAHW) can promote acicular ferrite by adding filler metal and additional heat input from the arc. However, LAHW may promote humping and adjustment of many parameters is required hindering its application. In this work, a 16 kW disk laser was used in butt welding of 12 mm and 15 mm thick plates with different bevelling geometries. Root humping occurred within a wide range of process parameters providing narrow process window. Twelve millimeter thick plates were successfully welded with a single-pass technique providing good quality of root by using zero air gap regardless bevelling geometry. Welding of 15 mm plates was more challenging, and the process was sensitive even with a slight parameter change. Improved results were achieved with application of small air gap. Acceptable hardness in both weld metal and heat affected zone (< 290 HV) was achieved for both plate thicknesses providing good toughness of minimum 27 J at −50°C.

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Section: Discussion On Root Qualitymentioning

confidence: 99%

Root formation and metallurgical challenges in laser beam and laser-arc hybrid welding of thick structural steel

Bunaziv

Dørum

Nielsen

et al. 2021

Int J Adv Manuf Technol

View full text Add to dashboard Cite

show abstract

“…This assumption can be validated by measuring the velocity inside the vapor plume (as shown in Ref. 23) in comparison with the velocity of the tracer particles (see Fig. 11) when observing the process from a side view (camera 1 in setup I, see Fig.…”

Section: Applicationmentioning

confidence: 93%

Experimental approach for quantification of fluid dynamics in laser metal welding

Tenner

Berg

Brock

et al. 2015

Journal of Laser Applications

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Laser metal welding is widely applied in industry. Nevertheless, a complete process understanding which leads to a full control of the process is not available yet. To contribute a solution for this task, we use two high-speed cameras with recording rates of up to 250 kHz and measure the velocity and direction of the fluid flow inside the keyhole with very high precision. Furthermore, we use tracer particles to measure the fluid dynamics in the keyhole. To get a deep view into the keyhole without the use of x-rays, we use a setup which allows us to look inside the keyhole during overlap welding of zinc-coated steel sheets with a spatial resolution of 25 μm per pixel and a temporal resolution of 5.3 μs per frame. Moreover, we quantify the influence of this approach on the process dynamics. Our findings show how the fluid dynamics inside the keyhole are linked to the laser power, the feed rate, and a gap between two zinc-coated steel sheets.

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“…This may be related to challenges in process observations and measurements related to high temperatures and evaporation phenomena [51]. During keyhole welding, high laser beam power causes high temperatures and evaporation rates resulting in strong recoil or dynamics pressure [52]. Possibly, the recoil pressure is not so high to cause the most determining factor on melt flows [53].…”

Section: Humping Mechanismmentioning

confidence: 99%

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Bunaziv

Dørum

Nielsen

et al. 2020

Int J Adv Manuf Technol

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High-power lasers are very effective in welding of plates thicker than 10 mm due to the keyhole mode. High-power intensity generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for single-pass welding of 12-to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (< 1.2 m/min) combined with lower laser beam power (< 13 kW) can be more positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma cut welded specimens. Higher heat input (> 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had good Charpy toughness at − 50°C (> 50 J) and high tensile strength.

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Experimental and Numerical Analysis of Gas Dynamics in the Keyhole During Laser Metal Welding

Cited by 23 publications

References 20 publications

Root formation and metallurgical challenges in laser beam and laser-arc hybrid welding of thick structural steel

Root formation and metallurgical challenges in laser beam and laser-arc hybrid welding of thick structural steel

Experimental approach for quantification of fluid dynamics in laser metal welding

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

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