Abstract
A three dimensionally integrated numerical framework using lattice Boltzmann method and multi-phase field method is proposed for simulating melting and solidification of metal alloy in laser powder bed fusion process. Modified lattice kinetic scheme that is a kind of lattice Boltzmann method is applied to simulate fluid flow consisting of atmosphere gas and melt liquid with free surface. Melting and solidification of metal alloy are modelled by multi-phase field method with consideration of grain anisotropy. Conserved Allen-Chan equation, which is also transformed to the modified lattice kinetic scheme formulation, is adapted to track the liquid-solid free surface moving dynamics. Thermal equation with heat source of traveling laser beam is solved by coupling fluid flow, melting and solidification analyses. Highly parallelized computational program is developed by MPI and OpenMP hybrid method. A three-dimensional model of the process for Ni alloy is built by consisting of atmosphere gas, base plate, and powder regions. Ni alloy powder, of which particle assumed sphere, is set by discreet element method in a condition of radius distribution. Simulations are performed in conditions of multi-beam tracking and multi-powder feeding.
