Predictive modeling of directed energy deposition of Ti6Al4V with the resultant microstructure

A multi-physics and multi-scale model developed is used to investigate the transport phenomena and resultant microstructure in the directed energy deposition process. A transient model with an improved level-set method is built to simulate the heat/mass transport and the dynamic evolution of the molten pool surface on the macro-scale. Solid state phase transformation during multi-track deposition is predicted by coupling the phase transformation model with the laser direct deposition model. A novel model integrating the Cellular Automata (CA) and Phase Field (PF) methods is used to simulate the dendritic growth of multi-component alloys in the mushy zone. The multi-scale model is validated against the experiments, and the predicted geometry of deposited tracks and the predicted phases of microstructure match reasonably well with the experimental results. The effects of the processing parameters on the track geometry and microstructure are also investigated.