When an electric welding arc heats an area of metal, a complex series of phenomena take place. Following heat transfer to the metal, a phase change from solid to liquid occurs under the arc, forming a weld pool. Inside the pool, convection currents begin to form, resulting from buoyancy, Lorentz forces, and shear stresses at the surface under the influence of volume expansion of the molten metal. Motion of the liquid metal impacts subsequent heat transfer and melting, and governs the final shape of the pool. Since it is the shape and temperature of the weld pool that dictates the quality of the welded joint, a comprehensive analysis of the procedure can be extremely helpful.

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The weld pool shape predicted is shown to agree well with experimental data.

Researchers at the ISF-Welding Institute of Aachen University of Technology in Germany have used our software to do this job. In the steady-state simulation, the position of the interface between the liquid and solid, called the melting line, was calculated for different welding conditions. The liquid surface was allowed to deform during the heating and melting process as a result of pressure from the arc and volume expansion of the liquid phase. Two cases were studied: one in which a deeper, narrower weld pool was expected and another in which a wider, shallower pool was expected. Different liquid currents were found to develop for these cases, consistent with laboratory observations. The researchers concluded that the software was an excellent tool to use for modeling these complex structures.