Modeling of Heat Transfer and Fluid Flow in the Laser Multilayered Cladding Process

The current work examines the heat-and-mass transfer process in the laser multilayered cladding of H13 tool steel powder by numerical modeling and experimental validation. A multiphase transient model is developed to investigate the evolution of the temperature field and flow velocity of the liquid phase in the molten pool. The solid region of the substrate and solidified clad, the liquid region of the melted clad material, and the gas region of the surrounding air are included. In this model, a level-set method is used to track the free surface motion of the molten pool with the powder material feeding and scanning of the laser beam. An enthalpy–porosity approach is applied to deal with the solidification and melting that occurs in the cladding process. Moreover, the laser heat input and heat losses from the forced convection and heat radiation that occurs on the top surface of the deposited layer are incorporated into the source term of the governing equations. The effects of the laser power, scanning speed, and powderfeed rate on the dilution and height of the multilayered clad are investigated based on the numerical model and experimental measurements. The results show that an increase of the laser power and powder feed rate, or a reduction of the scanning speed, can increase the clad height and directly influence the remelted depth of each layer of deposition. The numerical results have a qualitative agreement with the experimental measurements.