The wetting and stirring behavior of molten pool in narrow gap AMF-GTAW by numerical and experimental analysis

Abstract

The gas tungsten arc welding (GTAW) molten pool are numerical and experimentally determined to be wetting and stirring with an extra transverse alternating magnetic field (ETAMF). The trace particle behaviors in the molten pool were identified to demonstrate molten pool flow behavior with the use of a camera system in the GTAW process. Taking advantage of mathematical models, we present the calculated results of temperature fields, flow fields, pressure fields with and without ETAMF for comparison. The result revealed that reduction of the solid/liquid surface tension attributed to the periodic heating of the side walls facilitates the wetting and flow of the molten pool's edge, which takes on a critical significance to the formation of a concave liquid level in a narrow gap. Arc pressure, Lorentz force and arc shear force primarily accounted for the molten pool's flow and morphological change. As the arc deflected to one side wall, the liquid melt accumulated at the bottom of the side under the driving forces, accompanied by wetting and flow behavior. At equilibrium, the molten pool flowed outward the center of the anode point and eventually converged to the bottom of the other side wall. The variation of the arc deflection direction broke the previous equilibrium state, and the molten pool's flow direction is forced to change, resulting in a stirring effect.

Keywords

• Narrow gap GTAW
• Extra transverse alternating magnetic field
• Tracer particle
• Molten pool
• Stirring effect
• Wettability