Experimental determination of temperature threshold for melt surface deformation during laser interaction on iron at atmospheric pressure

Hirano, Kōji; Fabbro, R.; Muller, Maryse

doi:10.1088/0022-3727/44/43/435402

Cited by 96 publications

(48 citation statements)

References 33 publications

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“…[8][9][10][11] At high welding speed the surface of the liquid metal on the front wall of the keyhole is covered with small ripples or step like structures. With the help of a streak imaging technique developed by the authors [12] the velocity of these ripples has been measured and found to be in the order of 5-20m/s.…”

Section: Flow Desciptionmentioning

confidence: 99%

Melt behavior on the keyhole front during high speed laser welding

Eriksson

Powell

Kaplan

2013

Optics and Lasers in Engineering

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The flow of molten metal on the front wall of a laser generated welding keyhole has been observed by high speed photography, optically measured by mapping the flow of ripples on the liquid surface and theoretically calculated. A clear downward flow can be observed and measured by a Particle Image Velocimetry algorithm. A theoretical calculation of the melt thickness on the keyhole front is also presented. Results indicate that the thickness of the liquid on the keyhole front is similar to that of the resolidified layer found in micrographs of the front if the laser is suddenly turned off. The measured surface ripple flow speeds are between two and four times as high as the theoretical average fluid flow rate.

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Section: Flow Desciptionmentioning

confidence: 99%

Melt behavior on the keyhole front during high speed laser welding

Eriksson

Powell

Kaplan

2013

Optics and Lasers in Engineering

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“…This model contains all physical processes described previously and was used for the laser welding in [33], for the laser cutting [16] and for the laser drilling in [5,23] and [31]. The output of this 1D model are the drilling velocity, the ejection melt velocity and the surface temperature but only at a steady state.…”

Section: Introductionmentioning

confidence: 99%

Modeling laser drilling in percussion regime using constraint natural element method

et al. 2015

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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. Abstract The laser drilling process is the main process used in machining procedures on aeronautic engines, especially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects during manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simulation of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liquid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parameters.

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“…Despite this assumption was proposed nearly 40 years ago and widely adopted in modeling studies, 24,[29][30][31][32] it was only recently experimentally validated by some of the authors of this paper. 21 Their experimental demonstration challenges the well-known assumption of Semak and Matsunawa 33,34 that the keyhole temperature does not need to exceed the boiling point to support the opening of the keyhole during LW under atmospheric pressure. With the proposed ambient pressure dependent surface pressure model shown in Eq.…”

Section: Resultsmentioning

confidence: 95%

“…(1). 21 Moreover, it was also demonstrated that strong evaporation occurs in laser welding, only when the temperature of irradiated surface exceeds the boiling point of material. 21 Bearing these facts in mind, an improved model of recoil pressure for LW process under any ambient pressure p amb can be proposed, as shown in Fig.…”

Section: Theorymentioning

confidence: 99%

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Explanation of penetration depth variation during laser welding under variable ambient pressure

Pang¹,

Hirano²,

Fabbro³

et al. 2015

Journal of Laser Applications

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Science Arts & Métiers (SAM)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. It has been observed that the penetration depth during laser welding (LW) under vacuum or reduced ambient pressure could be significantly greater than that during welding under atmospheric pressure. Previous explanations of this phenomenon usually limit to specific wavelength laser welding and have difficulties in explaining why the variation will disappear, as the welding speed increases. Here, we propose that this variation is caused by the temperature difference of keyhole wall under variable ambient pressure based on a correct physical description of related processes.A new surface pressure model, dependent on ambient pressure, is proposed for describing the evaporation process during laser material interaction under variable ambient pressure. For laser welding of a 304 stainless steel with 2.0 kW laser power and 3 m/min welding speed, it is shown that the average keyhole wall temperature is around 2900 K under atmospheric pressure, and only around 2300 K under vacuum, which results in significant penetration depth variations. Interestingly, it is also shown that as the welding speed increases, the average temperature of the front keyhole wall gradually rises due to the reduction of the mean incident angle of laser, and the magnitude of this increase is larger in welding under vacuum than under atmospheric pressure. It allows us to explain why the penetration depth improvement decreases to zero with the increase of welding speed.

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Experimental determination of temperature threshold for melt surface deformation during laser interaction on iron at atmospheric pressure

Cited by 96 publications

References 33 publications

Melt behavior on the keyhole front during high speed laser welding

Melt behavior on the keyhole front during high speed laser welding

Modeling laser drilling in percussion regime using constraint natural element method

Explanation of penetration depth variation during laser welding under variable ambient pressure

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