Influence and Decreasing Strategies of Surface Defect and Roughness in Laser Powder Bed Fusion

Abstract The decrease in surface roughness of forming parts is a critical challenge for laser powder bed fusion (LPBF). The formation mechanisms of surface defects that increase the surface roughness of laser powder bed fused (LPBF‐ed) parts and the influence of surface roughness on properties are summarized in this review. The decreasing strategies and future perspectives for surface defects and roughness are discussed in detail. The surface defects of LPBF‐ed parts can be divided into six types and their formation mechanisms are usually related to the factors consisting of the energy input, melt pool dynamic behaviors, tracks fluctuation, and process of layers discretization of 3D part model. The surface roughness is increased greatly by the surface defects forming, which reduces the properties containing fatigue, corrosion resistance, and friction and wear seriously. The process control strategies of LPBF including process parameters optimization and online control can be used to decrease the surface roughness. It is found that the mechanical, laser, and chemical post‐treatment strategies can decrease the surface roughness effectively by reducing the surface defects. Furthermore, each process control strategy and post‐treatment strategy is compared and analyzed to select the most appropriate method, respectively. To decrease the surface defects and roughness and improve the properties of LPBF‐ed parts further, the future research directions are prospected.