Numerical Simulation and Analysis of Rough Surface Evolution of Laser Remelted 316L Stainless Steel

As a post-processing process of additive manufacturing, laser remelting can greatly improve the quality of laser selective melting formed parts. It is of great significance to study the influence mechanism of laser remelting process for the development of laser selective melting technology. Due to the rapid and microscopic evolution of rough surfaces during laser remelting, it is extremely challenging to analyze them using experimental methods. In this paper, based on the level set method, a multi-physics coupled finite element model is established to simulate and analyze the evolution process of rough surface during laser remelting. The model comprehensively considers the influence of energy density, Marangone effect and fluid mass transfer on surface morphology evolution. Through numerical simulation, it is found that in the process of laser remelting 316L stainless steel, the Marangoni effect plays an important role in the shape evolution of rough surface. Due to the fluid flow under the Marangoni effect, the uneven surface becomes smooth, and the surface roughness is improved. The effectiveness of the simulation is verified by experiments. The experimental results show that the surface roughness after laser remelting is reduced to different degrees, and the Ra and Sa values of the surface roughness are reduced by 54.4% and 68.3%, respectively, which is consistent with the trend of the simulation results. In addition, the changes of the roughness under different laser remelting power and scanning speed were analyzed by numerical simulation.