A complete model of keyhole and melt pool dynamics to analyze instabilities and collapse during laser welding

A complete modeling of heat and fluid flow applied to laser welding regimes is proposed. This model has been developed using only a graphical user interface of a finite element commercial code and can be easily usable in industrial R&D environments. The model takes into account the three phases of the matter: the vaporized metal, the liquid phase, and the solid base. The liquid/vapor interface is tracked using the Level-Set method. To model the energy deposition, a new approach is proposed which consists of treating laser under its wave form by solving Maxwell's equations. All these physics are coupled and solved simultaneously in Comsol Multyphysics®. The simulations show keyhole oscillations and the formation of porosity. A comparison of melt pool shapes evolution calculated from the simulations and experimental macrographs shows good correlation. Finally, the results of a three-dimensional simulation of a laser welding process are presented. The well-known phenomenon of humping is clearly shown by the model.

[1]  Y. Shin,et al.  Investigation of keyhole plume and molten pool based on a three-dimensional dynamic model with sharp interface formulation , 2013 .

[2]  S. Ko,et al.  Mechanism of keyhole formation and stability in stationary laser welding , 2002 .

[3]  P. Masson,et al.  A new approach to compute multi-reflections of laser beam in a keyhole for heat transfer and fluid flow modelling in laser welding , 2013 .

[4]  C. Knight.  Theoretical Modeling of Rapid Surface Vaporization with Back Pressure , 1979 .

[5]  S. Katayama,et al.  Dynamics of keyhole and molten pool in laser welding , 1998 .

[6]  R. Fabbro,et al.  Experimental determination of temperature threshold for melt surface deformation during laser interaction on iron at atmospheric pressure , 2011 .

[7]  M. Sajid.  A contribution towards the numerical study of bubble dynamics in nucleate boiling at local scale using a conservative level set method , 2010 .

[8]  S. Ohnimus,et al.  Modeling buckling distortion of DP600 overlap joints due to gas metal arc welding and the influence of the mesh density , 2009 .

[9]  J. Mazumder,et al.  A Numerical Method for Multiphase Incompressible Thermal Flows with Solid–Liquid and Liquid–Vapor Phase Transformations , 2005 .

[10]  G. Tryggvason,et al.  Computations of film boiling. Part I: numerical method , 2004 .

[11]  F. Vollertsen,et al.  Numerical simulation of molten pool dynamics in high power disk laser welding , 2012 .

[12]  Manfred Geiger,et al.  A 3D transient model of keyhole and melt pool dynamics in laser beam welding applied to the joining of zinc coated sheets , 2009, Prod. Eng..

[13]  Meiko Boley,et al.  Novel X-ray System for in-situ Diagnostics of Laser Based Processes - First Experimental Results , 2011 .

[14]  Sonia Slimani,et al.  Analysis of the various melt pool hydrodynamic regimes observed during cw Nd-YAG deep penetration laser welding , 2007 .

[15]  M. Rethmeier,et al.  Plume attenuation of laser radiation during high power fiber laser welding , 2011 .

[16]  Tao Chen,et al.  A three-dimensional sharp interface model for self-consistent keyhole and weld pool dynamics in deep penetration laser welding , 2011 .

[17]  Genyu Chen,et al.  Direct observation of keyhole characteristics in deep penetration laser welding with a 10 kW fiber laser. , 2013, Optics express.

[18]  J. Mazumder,et al.  Modeling of laser keyhole welding: Part I. mathematical modeling, numerical methodology, role of recoil pressure, multiple reflections, and free surface evolution , 2002 .