Thermal-fluid dynamic behavior and its effect on particle distribution and solidification characterization during the laser melting deposition of Ti-based composites

Laser melting deposition (LMD) is an advanced repairing and remanufacturing technology that involves complex thermodynamic and kinetic characteristics in a molten pool. A thorough understanding of the thermal-fluid dynamic behavior of molten metal is crucial for investigating the distribution of reinforced particles and the characterization of solidification. This study proposes a three-dimensional transient thermal-fluid coupling model for describing thermal-fluid dynamic behavior and particle migration behavior within a molten pool during LMD. The simulated morphology of the deposition layer and temperature agree well with the experiments. The simulation results indicate that Marangoni convection induced by temperature gradient dominates the convection mode. The fluid velocity distribution along the scanning direction of the molten metal is showing M shape. Meanwhile, the dimension of molten pool increases slightly, and the Marangoni convection becomes more vigorous with higher heat input. The Marangoni motion tends to drive the TiC particle migration from the center to both lateral sides, resulting in a more uniformly distributed of TiC particle in deposition layer. Furthermore, the solidification parameters at solid–liquid interface are calculated, which used to assess the solidification microstructure in deposition layer.