Solidification Microstructure Evolution Model for Laser Cladding Process

摘要

The laser cladding process inherently includes multiscale, highly nonlinear, and non-equilibrium transport phenomena due to nonuniform and rapid heat flow caused by the laser and the material interaction. In this work, a process model of solidification micro-structure evolution for the laser cladding process has been studied by utilizing a phase-field method. The phase-field method has become a widely used computational tool for the modeling of solidification micro-structure evolution with the advantage of avoiding tracking the interface explicitly and satisfying interfacial boundary conditions. In the present work, the numerical solutions of a phase-field model have been analyzed. The linking of the macroscale process and solidification microstructure evolution was examined by considering the relationship of macro- and micro-parameters. The effects of melt undercooling and anisotropy on the solidification micro-structure have also been studied. The predicted results with different undercoolings were compared with the microsolvabil-ity theory and a good agreement was found. Different solidification morphologies of different locations in the melt-pool are also investigated. To quantitatively study the effect of heat flux on the dendritic growth, the dendrite tip analysis was carried out. It was observed that the dendrite tip that grows in the same direction with the heat flux shows a much higher velocity than a tip that grows in the opposite direction of the heat flux.