Morphology evolution of molten pool of β-Ti/Ti6Al4V based on the modified double ellipsoidal heat source model of SLM

The SLM (Selective Laser Melting) process involves a complex evolution. Experimental observation combined with numerical simulation analysis is an important way to study the evolution of molten pools. This study aims to improve the accuracy of numerical prediction for the evolution of microstructure (β grains and phases) during the cooling process of the molten pool, and combine with experimental results to gain a comprehensive understanding of the morphology characteristics of the melt pool and the micro mechanism of material forming. The β-Ti/Ti6Al4V specimens are prepared by using the selective laser melting equipment, and then the effect of process parameters on the molten pool micro-morphology is analyzed. A heat source model on the basis of experimental data is developed to provide the correlation between melt pool morphology and process. Numerical simulation and experimental investigation are applied to study the melt pool temperature field, velocity field and microstructure evolution. It is indicated that the shape of the molten pool after the modified heat source model agrees with the experimental methods. Furthermore, the analysis of the microstructure evolution of the molten pool during the solidification process is combined with the temperature field obtained from the simulation, and then the evolution of microstructure (β grains and phases) during the cooling process of the molten pool was also predicted. The accuracy of the analysis is verified by the experimental results.