Effect of Electromagnetic Stirring on Melt Pool Solidification of Laser Melting TA15 Titanium Alloy

Abstract:

In order to study the effect of electromagnetic stirring on melt pool solidification, a three-dimensional magnetic-thermal coupling numerical simulation was conducted on the process of single-pass laser melting TA15 titanium alloy with and without the magnetic field based on the finite volume method. The influence of electromagnetic field on temperature field, flow field, temperature gradient and solidification rate were analyzed. Then the numerical simulations were verified by experiment method. The results of numerical simulations showed that the melt pool maximum flow velocity increased by 20%, which promoted the function of heat exchange resulting in going down of the highest temperature of melt pool and temperature gradient on solid-liquid interface, and meanwhile the small rise in solidification rate, which were good for columnar-to-equiaxed transition at the top of melt pool. The experiment results indicated some equiaxed grains were generated at the top of melt layer with the magnetic field. Electromagnetic force was enlarged with an increase of the distance from magnetic field center, which causes equiaxed grain zone had a tendency to expand. The numerical simulations were in good agreement with the experimental results.

Key words:Laser melting; Electromagnetic stirring; TA15 titanium alloy; Finite volume method; Columnar-to-Equiaxed Transition