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    • Keywords


      Ambient and under water welding; keyhole collapse; weld depth instabilities; humps

    • Abstract


      The study of keyhole (KH) instability in deep penetration laser beam welding (LBW) is essential to understand welding process and appearance of weld seam defects. The main cause of keyhole collapse is the instability in KH dynamics during the LBW process. This is mainly due to the surface tension forces associated with the KH collapse and the stabilizing action of vapour pressure. A deep penetration high power CW CO2 laser was used to generate KH in mild steel (MS) in two different welding conditions i.e. ambient atmospheric welding (AAW) and under water welding (UWW). KH, formed in case of under water welding, was deeper and narrower than keyhole formed in ambient and atmospheric condition. The number and dimensions of irregular humps increased in case of ambient and under water condition due to larger and rapid keyhole collapse also studied. The thermocapillary convection is considered to explain KH instability, which in turn gives rise to irregular humps.

    • 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
    • Dates

  • Sadhana | News

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