Transition from Stable Laser Fusion Cutting Conditions to Incomplete Cutting Analysed with High-speed X-ray Imaging

Lind, Jannik; Fetzer, Florian; Hagenlocher, Christian; Blázquez-Sánchez, David; Weber, Rudolf; Graf, Thomas

doi:10.1016/j.jmapro.2020.10.068

Cited by 11 publications

(3 citation statements)

References 19 publications

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“…The 3D-geometry of the capillary was reconstructed from the recorded images as described in [18,19]. Based on Beers absorption law of the X-ray radiation that is transmitted through the samples, the geometrical extension of the capillary along propagation direction of the X-ray beam is given by:…”

Section: Determination Of the Absorptance Of The Vapor Capillariesmentioning

confidence: 99%

“…The attenuation coefficient for the monochrome X-ray beam with 37.7 keV in solid aluminum amounts to µ sol = 1.8 cm −1 [20], and linearly depends on the density of the material [21]. As described in [18] the presence of a liquid phase causes a systematic error which results from its decreased density. To take this into account and to estimate the range of possible extensions of the capillary in the direction along the X-ray beam, Equation (1) was solved for both, the attenuation coefficient µ sol = 1.8 cm −1 of the solid material and for the one of the liquid material given by µ liq = µ sol • ρ liq /ρ sol = 1.58 cm −1 and with the corresponding densities ρ liq (T = 700 • C) = 2370kg/m 3 and ρ sol (T = 20 • C) = 2700 kg/m 3 , respectively [15].…”

Section: Determination Of the Absorptance Of The Vapor Capillariesmentioning

confidence: 99%

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Synchrotron X-ray Analysis of the Influence of the Magnesium Content on the Absorptance during Full-Penetration Laser Welding of Aluminum

Wagner

Hagenlocher

Hummel

et al. 2021

Metals

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Full-penetration laser beam welding is characterized by a weld seam whose depth equals the material thickness. It is associated with a stable capillary and is therefore widely used for welding of sheet metal components. The realization of lightweight concepts in car body production requires the application of high-strength aluminum alloys that contain magnesium as an alloying element, which significantly influences the evaporation temperature and pressure. This change of the evaporation processes influences the geometry of the capillary and therefore its absorptance. In order to quantify the influence of magnesium on the capillary, their geometries were captured by means of high-speed synchrotron X-ray imaging during the welding process of the aluminum alloys AA1050A (Al99.5), AA5754 (AlMg3) and AA6016 (AlSi1.2Mg0.4). The 3D-geometries of the capillaries were reconstructed from the intensity distribution in the recorded X-ray images and their absorptance of the incident laser beam was determined by the analysis of the reconstructed 3D-geometry with a raytracing algorithm. The results presented in this paper capture for the first time the influence of the magnesium content in high-strength aluminum alloys on the aspect ratio of the capillary, which explains the reduced absorptance in case of full-penetration laser beam welding of aluminum alloys with a high content of volatile elements. In order to improve the absorptance in full-penetration welding, these findings provide the information required for the deduction of new optimization approaches.

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Section: Determination Of the Absorptance Of The Vapor Capillariesmentioning

confidence: 99%

Section: Determination Of the Absorptance Of The Vapor Capillariesmentioning

confidence: 99%

Synchrotron X-ray Analysis of the Influence of the Magnesium Content on the Absorptance during Full-Penetration Laser Welding of Aluminum

Wagner

Hagenlocher

Hummel

et al. 2021

Metals

Self Cite

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“…This is determined from the intensity distribution of the transmitted radiation and the known attenuation of the corresponding x-rays in the weld sample, according to Beer-Lambert's law. A detailed description of the reconstruction algorithm is presented in [8]. The 3D-geometry of the keyhole that corresponds to the x-ray image in Fig.…”

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confidence: 99%

Coherent beam combining – unlimited flexibility in laser material processing

Wagner

Leis²,

Armon³

et al. 2022

PhotonicsViews

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Adjustment of the geometries of the cutting front and the kerf by means of beam shaping to maximize the speed of laser cutting

Lind

Hagenlocher

Weckenmann

et al. 2023

Int J Adv Manuf Technol

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The shape of the laser beam used for fusion cutting significantly influences the geometry of both the cutting front and the cutting kerf. The angle of the cutting front in turn impacts the local absorptivity, while the width of the kerf defines the amount of material, which has to be molten. The kerf’s geometry therefore determines the maximum possible cutting speed at which a successful cut is feasible with a given available laser power. The absorptivity, the width of the kerf, and the maximum possible cutting speed can be estimated from a simple model considering the conservation of energy and rough geometrical approximations. In order to verify the prediction of the model, the geometry of the cutting front and kerf resulting from different processing conditions was observed by means of online high-speed X-ray diagnostics. The geometry of the interaction zone was recorded with a framerate of 1000 Hz during fusion cutting of 10-mm-thick samples of stainless steel. Comparing the results obtained with different shapes of the laser beam, it was found that the absorptivity is increased when the beam’s longitudinal cross-section (parallel to the feed) is enlarged. Reducing the width of the beam in the transversal direction normal to the feed reduces the cross-sectional area of the cutting kerf. The findings show a good agreement with the geometric model which enabled the prediction of the absorptivity and the cross-sectional area of the cutting kerf and hence allows to reliably estimate the maximum cutting speed for different shapes of the laser beam, laser power, and sheet thicknesses.

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Transition from Stable Laser Fusion Cutting Conditions to Incomplete Cutting Analysed with High-speed X-ray Imaging

Cited by 11 publications

References 19 publications

Synchrotron X-ray Analysis of the Influence of the Magnesium Content on the Absorptance during Full-Penetration Laser Welding of Aluminum

Synchrotron X-ray Analysis of the Influence of the Magnesium Content on the Absorptance during Full-Penetration Laser Welding of Aluminum

Coherent beam combining – unlimited flexibility in laser material processing

Adjustment of the geometries of the cutting front and the kerf by means of beam shaping to maximize the speed of laser cutting

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