Numerical modeling of direct metal deposition: Heat transfer/solute transport of ternary system

Abstract

Laser aided Direct Metal Deposition (DMD) process is used for rapid prototyping, tooling and die production, and repairing damaged parts or worn parts by depositing metal powders. Numerical simulation of DMD process helps provide optimal process parameters for better mechanical / thermal properties of products without performing a series of experiments. In this paper, a 3D-transient numerical model for DMD process is presented with considering couplings between temperature, velocity / pressure, and composition. Energy conservation and modified Navier-Stoke equations have been applied to predict temperature and velocity / pressure fields, respectively, and the compositional variation of each element during deposition has been obtained using solute concentration equation. Due to high cooling rates in laser material processing, non-equilibrium partitioning for solidification process has been considered in this study. From the computed solidus / liquidus solute concentrations using non-equilibrium partitioning (during solidification), dynamic non-equilibrium phase diagram of each element is constructed. Then, liquid mass fraction is obtained with equilibrium phase diagram (during melting) and the constructed non-equilibrium phase diagram.Laser aided Direct Metal Deposition (DMD) process is used for rapid prototyping, tooling and die production, and repairing damaged parts or worn parts by depositing metal powders. Numerical simulation of DMD process helps provide optimal process parameters for better mechanical / thermal properties of products without performing a series of experiments. In this paper, a 3D-transient numerical model for DMD process is presented with considering couplings between temperature, velocity / pressure, and composition. Energy conservation and modified Navier-Stoke equations have been applied to predict temperature and velocity / pressure fields, respectively, and the compositional variation of each element during deposition has been obtained using solute concentration equation. Due to high cooling rates in laser material processing, non-equilibrium partitioning for solidification process has been considered in this study. From the computed solidus / liquidus solute concentrations using non-equilibrium partitionin...