An Integrated Multiscale Model to Study the Marangoni Effect on Molten Pool and Microstructure Evolution

Microstructure plays a crucial role in predicting the properties of parts by additive manufacturing. Fluid flow and temperature gradient are always recognized as key factors influencing the final microstructure. However, the effects of flow field were often ignored during microstructure simulation inside the molten pool. In this study, the Marangoni flow is firstly calculated using the finite element method. Fluid flow increases the temperature gradient and the cooling rate at the solid front. Subsequently, the temperature field and flow field are input to phase-field model to simulate the microstructure inside the molten pool. This integrated model is then applied to study the solidification behavior of IN718 alloy during additive manufacturing. The microstructure evolutions are analyzed in detail under different processing parameters. The simulation results demonstrate that the Marangoni flow has great effects on both molten pool and solidification microstructure. The integrated model developed in this work can predict the molten pool and solidification microstructure more accurately by combining the thermal, flow and microstructure models together.