Prevention of solidification cracking by use of a diode laser superposition in pulsed laser beam welding

Martin Bielenin; Leander Schmidt; Klaus Schricker; Jean Pierre Bergmann

doi:10.1117/12.2507031

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27 February 2019 Prevention of solidification cracking by use of a diode laser superposition in pulsed laser beam welding

Martin Bielenin, Leander Schmidt, Klaus Schricker, Jean Pierre Bergmann

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Proceedings Volume 10911, High-Power Laser Materials Processing: Applications, Diagnostics, and Systems VIII; 109110W (2019) https://doi.org/10.1117/12.2507031
Event: SPIE LASE, 2019, San Francisco, California, United States

Abstract

This paper investigates laser welding of AA 6082 by superimposing a pulsed Nd:YAG laser with a continuous wave diode laser in order to reduce the hot-cracking susceptibility. Conventional pulsed laser welds exhibit severe solidification cracking on the application of a conventional rectangular laser pulse shape. Through the superposition of a Nd:YAG and diode laser beam crack-free welds can be realized without the use of an additional filler material in the case of sheet thickness of 0.5 mm. The diode laser beam simultaneously heats the base metal and weld metal during the melt-pool solidification and compensates solidification shrinkage and thermal contraction. Furthermore, the superimposed diode laser reduces the cooling rate during the melt-pool solidification. Hot-cracking can be eliminated by using an additional diode laser with a low output power of approximately 300W. A major impact of the diode laser superposition on the hot-crack suppression is expected to be achieved by reducing the solidification rate during the melt-pool solidification. These thermal changes result in coarser microstructure and therefore enable the easier feeding of liquid into the interdendritic cavities.

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Martin Bielenin, Leander Schmidt, Klaus Schricker, and Jean Pierre Bergmann "Prevention of solidification cracking by use of a diode laser superposition in pulsed laser beam welding", Proc. SPIE 10911, High-Power Laser Materials Processing: Applications, Diagnostics, and Systems VIII, 109110W (27 February 2019); https://doi.org/10.1117/12.2507031

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