Particle-scale computational fluid dynamics simulation on selective parallel dual-laser melting of nickel-based superalloy

Abstract

A three-dimensional high-fidelity particle-scale computational fluid dynamics (CFD) modeling of a selective parallel dual-laser melting (SPDLM) process is developed, on which dynamics behavior of molten pools of Nickel-based superalloy during SPDLM is simulated. The phenomena of wetting, necking, and pores near the overlapping region in the parallel dual-laser molten pools are especially investigated. The simulated results show that the SPDLM process improves the re-melting rate of the molten pool and the wettability of the overlapping region of the SPDLM molten pool, reducing the probability of defects, especially the probability of lack of fusion. Due to the uniform temperature distribution in the overlapping region of the two tracks and the complete melting, the product quality at the overlapping region of the two molten pools can be better guaranteed when the interval between the parallel dual lasers is 2.5 times of the laser beam radius. The results suggest that the SPDLM technique together with appropriate process parameters can not only increase the printing efficiency, but also improve the surface quality of the overlapping area of the two molten pools. The simulated results also reveal the formation mechanisms of pore defects during the selective multi-laser melting process on a mesoscopic scale. This study shows that the proposed particle-scale CFD model provides a high fidelity approach to characterize the molten pool in the SPDLM process and, therefore, is helpful for the optimal process design for the selective multi-laser melting.