Analysis of molten pool behavior with buttonhole formation in laser keyhole welding of sheet metal

A cavity, so-called buttonhole, was observed in the molten pool directly behind the oscillating laser beam and the supplied wire by means of suitable process control. A high seam surface quality was produced in the case with the buttonhole formation. A three-dimensional heat and mass transfer model was developed to understand the effect of the buttonhole in laser keyhole welding of sheet metal with a filler wire and one-dimensional laser beam oscillation. For a given welding condition, a stable catenoid-like button-hole was shown which helped to reduce molten pool dynamics by its self-sustainability. The buttonhole formation was sensitive to the welding parameter of the air gap. (C) 2020 Elsevier Ltd. All rights reserved.