Comparison of heat conduction mode and deep penetration mode by means of high-speed synchrotron X-ray videos during laser beam welding (doi:10.18419/darus-2078)

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Comparison of heat conduction mode and deep penetration mode by means of high-speed synchrotron X-ray videos during laser beam welding

doi:10.18419/darus-2078

DaRUS

2021-08-04

2

Hagenlocher, Christian; Lind, Jannik; Wagner, Jonas; Hummel, Marc; Olowinsky, Alexander; Weber, Rudolf; Graf, Thomas, 2021, "Comparison of heat conduction mode and deep penetration mode by means of high-speed synchrotron X-ray videos during laser beam welding", https://doi.org/10.18419/darus-2078, DaRUS, V2

Comparison of heat conduction mode and deep penetration mode by means of high-speed synchrotron X-ray videos during laser beam welding

doi:10.18419/darus-2078

Hagenlocher, Christian (University of Stuttgart)

Lind, Jannik (University of Stuttgart, Precitec GmbH & Co. KG)

Wagner, Jonas (University of Stuttgart)

Hummel, Marc (RWTH Aachen University)

Olowinsky, Alexander (Fraunhofer Institute for Laser Technology ILT)

Weber, Rudolf (University of Stuttgart)

Graf, Thomas (University of Stuttgart)

2020-10-01

236616214

DaRUS

Hagenlocher, Christian

Darus Admin IFSW

Hagenlocher, Christian

2021-07-14

https://doi.org/10.18419/darus-2078

Engineering, laser beam welding, high-speed synchrotron X-ray imaging, capillary behavior, pore formation

There are two modes of laser beam welding: the heat conduction mode and the full penetration mode. The heat conduction mode is present if the intensity of the laser beam is to low to evaporate but sufficient to melt the irradiated material. This welding mode results in a very stable process without pore formation but with low welding depths. The strong evaporation in case of higher laser beam intensities leads to the formation of a vapour capillary, whose presence defines the deep penetration mode. The capillary enables high welding depths but coincides with instabillities, which may form pores in the weld seam. In order to compare the welding modes, the space- and time-resolved geometry of the capillary and the melt pool were captured during laser beam welding of aluminium with a framerate of 1000 Hz by means of high-speed synchrotron X-ray imaging. Both Experiments were conducted with a laser power of 1 kW and a welding velocity of 6 m/min. In order to weld in heat conduction mode, the intensity of the laser beam was reduced by shifting the focal position 5 mm above the surface of the sample. The crossections of the reulting weld seam are depicted below their corresponding X-ray-video.

The presented investigations were carried out in cooperation with DESY in Hamburg and with RWTH Aachen University within the framework of the Collaborative Research Centre SFB1120-236616214 “Bauteilpräzision durch Beherrschung von Schmelze und Erstarrung in Produktionsprozessen” and funded by the Deutsche Forschungsgemeinschaft e.V. (DFG, German Research Foundation). We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III and we would like to thank F. Beckmann and J. Moosmann for assistance in using P07 EH4. Beamtime was allocated for proposal I-20191140.The sponsorship and support is gratefully acknowledged.

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Modes_of_Laser_Welding.avi

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The video presents the heat conduction welding mode in the upper left and the deep penetration welding mode in the upper right. The metallographically prepared cross sections of the resulting welds are depicted below the corresponding video.

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