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    • Keywords


      Keyhole; melt pool; vorticity; dimensionless numbers; liquid–vapour phase.

    • Abstract


      In the present study, the vorticity of melt motion in the keyhole and weld pool has been evaluated in case of high power CO2 laser beam welding. The circulation of vorticity is obtained as a function of Reynolds number for a given keyhole volume which is linked to Mach number variation. The shear stress and thermal fluxes present in the turbulent pool are linked to diffusivity and Prandtl number variation. It was shown that below a critical value of Rayleigh number, the conduction mode of melt transfer signifying beam absorption becomes dominant. Above this value, convective heat transfer indicates melting and evaporation occurring in the weld pool during laser welding. The evaporative recoil pressure expels the liquid while surface tension and hydrostatic pressure help to retain the melt in the keyhole cavity in this high power laser beam welding. The understanding of several hydrodynamic phenomena occuring in the weld pool is valuable not only for understanding basic mechanistic aspects but also for process optimization involved in laser beam welding.

    • Author Affiliations


      N Kumar1 S Dash1 A K Tyagi1 Baldev Raj1

      1. Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
    • Dates

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