On modeling of heat transfer and molten pool behavior in multi-layer and multi-track laser additive manufacturing process

摘要

In this paper, the processes accompanying multitrack and multilayer selective laser melting of metal powder are studiedby methods of multiscale numerical simulation. The model includes the coupled macro-scale balance equations of energyand momentum, describing heat transfer, fluid flow and phase transformations, while modeling the structure of thedeposited layer by the discrete elements method. The features of the processes of heat transfer and the formation of themelt pool are studied, the surface profile and the relative density (porosity) of the synthesized sample of stainless steel304 are determined. The calculated values of the final porosity coincide with the experimental data. On the micro-scale,a phase field method characterized by a self-consistent thermodynamic approach and universality is used to describephase transitions and structure formation dynamics. The numerical implementation of the microstructure evolutionmicromodel is carried out, the dynamics of morphology and growth of columnar dendritic microstructures in the processof selective laser melting is analyzed. The influence of the governing parameters of the model and the process on theformation of stress fields in dendritic crystal structures is studied.