The action of a laser generates a keyhole in the work piece surrounded by a molten weld pool when it is used for the deep penetration welding of metals. The boundary of the weld pool is the melting isotherm of the metal and its cross sectional shape varies with depth when viewed from above the pool. The circulation pattern is the combined result of the translation of the work piece relative to the laser beam and the flow induced by variation of the surface tension caused by the presence of the substantial temperature gradients that exist in the weld pool. The derivative of the surface tension with respect to the temperature can, furthermore, change sign in the presence of suitable traces of contaminants whose concentration need only be to the extent of a few parts per million. Powerful thermocapillary surface forces result which can cause a rapid flow near the surface of the weld pool. This paper formulates the problem of modelling mathematically the flow in the weld pool caused by a combination of the translation of the work piece and the presence of these thermocapillary flows. It is shown that the three-dimensional flow in the weld pool can be studied using a representation of the thermocapillary boundary layer as a surface condition imposed on the otherwise inviscid equations of motion for the flow in the weld pool.
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ICALEO '97: Proceedings of the Laser Materials Processing Conference
November 17–20, 1997
San Diego, California, USA
ISBN:
0-912035-56-0
PROCEEDINGS PAPER
Thermocapillary flows in the weld pool formed during laser welding, investigated mathematically Available to Purchase
John Dowden;
John Dowden
1
Department of Mathematics, University of Essex
, Colchester CO4 3SQ, UK
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Phiroze Kapadia;
Phiroze Kapadia
2
Department of Physics, University of Essex
, Colchester CO4 3SQ, UK
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Pablo Solana
Pablo Solana
2
Department of Physics, University of Essex
, Colchester CO4 3SQ, UK
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Published Online:
November 01 1997
Citation
John Dowden, Phiroze Kapadia, Pablo Solana; November 17–20, 1997. "Thermocapillary flows in the weld pool formed during laser welding, investigated mathematically." Proceedings of the ICALEO '97: Proceedings of the Laser Materials Processing Conference. ICALEO '97: Proceedings of the Laser Materials Processing Conference. San Diego, California, USA. (pp. pp. G219-G228). ASME. https://doi.org/10.2351/1.5059726
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