Numerical and experimental investigation of thermo-fluid flow and element transport in electromagnetic stirring enhanced wire feed laser beam welding

Abstract

The introduction of electromagnetic stirring to laser beam welding can bring several beneficial effects e.g. element homogenization and grain refinement. However, the underlying physics has not been fully explored due to the absence of quantitative data of heat and mass transfer in the molten pool. In this paper, the influence of electromagnetic stirring on the thermo-fluid flow and element transport in the wire feed laser beam welding is studied numerically and experimentally. A threedimensional transient heat transfer and fluid flow model coupled with dynamic keyhole, magnetic induction and element transport is developed for the first time. The results suggest that the Lorentz force produced by an oscillating magnetic field and its induced eddy current shows an important influence on the thermo-fluid flow and the keyhole stability. The melt flow velocity is increased by the electromagnetic stirring at the rear and lower regions of molten pool. The keyhole collapses more frequently at the upper part. The additional elements from the filler wire are significantly homogenized because of the enhanced forward and downward flow. The model is well verified by fusion line shape, high-speed images of molten pool and measured element distribution. This work provides a deeper understanding of the transport phenomena in the laser beam welding with magnetic field.

The influence of magnetic field orientation on metal mixing in electromagnetic stirring enhanced wire feed laser beam welding

“…20°angle. An upward flow forms under the magnetic field of 40°, which is analogous to the flow pattern of the welding case without magnetic field (Meng et al, 2019b). Thus, there is evidence to suggest that the Lorentz force has attenuated to a minor level due to the stronger skin effect.…”

“…However, the keyhole profile in this study was fixed for simplification. In the authors' recent work, a more comprehensive multi-physical model was developed for the electromagnetic stirring enhanced wire feed laser beam welding (EMS-WFLBW), in which the heat transfer, fluid flow, element transport, keyhole dynamics and MHD were all considered selfconsistently (Meng et al 2019b). The molten pool behaviors with and without magnetic field were compared in detail to obtain an intuitive explanation to the benefits on the filler metal mixing from an EMS.…”

Numerical Analysis of the Partial Penetration High Power Laser Beam Welding of Thick Sheets at High Process Speeds

“…The multi-physics model is based on several previous works with some further improvements and adaptions. More details can be obtained from the authors' previous works [46][47][48][49][50]. Note that only the main physical features of the welding process are formulated concisely in the manuscript; thus the emphasis is on the improvements in the model, especially on the ray tracing approach.…”

Elucidation of the Bulging Effect by an Improved Ray‐Tracing Algorithm in Deep Penetration Wire Feed Laser Beam Welding and Its Influence on the Mixing Behavior

“…Further details of the numerical model can be found in other studies. [3,[28][29][30][31] The main governing equations in a fixed Cartesian coordinate system are summarized.…”