Experimental investigation of the melt flow in aluminum during laser welding with magnetic stirring

Abstract

The idea of applying a low frequency magnetic field during laser welding process has been already carried out recently in order to make a stir effect inside the molten pool and therefore to improve the element dilution in the weld joint. However, the mechanism of magnetic stirring by laser welding process is still lacking a clear understanding yet. A big problem on the way is that neither the molten pool nor the element dilution can be easily observed during welding, which makes it difficult to realize a systematic and comprehensive investigation on the influences of magnetic parameters on the element distribution.In this paper, the effects of the magnetic field on the melt flow as well as the element dilution are shown by applying copper as “tracer” inside the molten pool. Several methods designed with different forms of copper at different positions in the workpieces to visualize the melt flow and the corresponding element dilution in different areas of the molten pool. The results demonstrate that a DC magnetic field, with its direction coaxial to the laser, tends to modify the melt flow dynamics by flux density up 100mT. The results of laser welding with filler wire showed that by the help of an AC magnetic field with frequency up to 10 Hz and flux density above 100mT, the element dilution could be improved in the weld joint.The idea of applying a low frequency magnetic field during laser welding process has been already carried out recently in order to make a stir effect inside the molten pool and therefore to improve the element dilution in the weld joint. However, the mechanism of magnetic stirring by laser welding process is still lacking a clear understanding yet. A big problem on the way is that neither the molten pool nor the element dilution can be easily observed during welding, which makes it difficult to realize a systematic and comprehensive investigation on the influences of magnetic parameters on the element distribution.In this paper, the effects of the magnetic field on the melt flow as well as the element dilution are shown by applying copper as “tracer” inside the molten pool. Several methods designed with different forms of copper at different positions in the workpieces to visualize the melt flow and the corresponding element dilution in different areas of the molten pool. The results demonstrate that a DC...