Thermoelectric Magnetohydrodynamic Model for Laser-Based Metal Additive Manufacturing

Magnetic fields are recently being applied to metal additive manufacturing to control the molten pool dynamics and dendritic morphology. To study the molten pool dynamics under an external magnetic field, a thermoelectric magnetohydrodynamic (TEMHD) model is developed by incorporating the electrodynamic model with the Seebeck effect into the multiphysics thermal-fluid flow model. The Seebeck effect in the molten pool is analyzed with the simulation of stationary laser melting on a bare plate. Furthermore, different external magnetic fields are assigned in the TEMHD simulations with the stationary laser melting and the results show that the Lorentz force can damp the keyhole fluctuations. Finally, the laser scanning simulations on a bare plate under external magnetic fields indicate that the Lorentz force can smooth the fluid flow fields in the molten pool and increase the ratio of equiaxed grains in the solidification front.