Quantitative-regulated material removal rate in solid dielectric electrochemical polishing (QRR-SDEP) for smoothing high roughness surface of additively manufactured 316L stainless steel components

Despite the widespread adoption of metal additive manufacturing (AM) technologies across various industries, the high-performance requirements in precision scenarios make the optimization of surface quality for AM parts crucial. Herein, we present a quantitative-regulated material removal rate in solid dielectric electrochemical polishing (QRR-SDEP) method, which utilizes the impedance variation of solid dielectric to dynamically control the material removal rate (MRR) according to the evolution of the surface roughness. Based on quantitative analysis, MRR can be continuously regulated from tens of nm/min to several pm/min for three SDEP stages. Through modulating the MRR, laser powder bed fusion additively manufactured (AM-ed) surface with an initial roughness (Ra) of approximately 10 pm down to Ra= 0.75 pm (evaluation length 4 mm) and Sa= 0.66 pm (evaluation area 1220 x1220 pm2) by employing an eco-friendly sulfate-free electrolyte. The improvement of Ra and Rz exceeds 92% and 94%, respectively. In addition, the evolution process of surface morphology and element compositions of polished AM-ed surfaces are discussed. The material removal mechanism of the QRRSDEP process for high-roughness surfaces is also explained. Compared to conventional electrochemical polishing, QRR-SDEP achieves a leapfrog polishing from highly rough to submicron surfaces for intricate-shaped AM components without generating any waste electrolytes. As a result, QRR-SDEP will propel the extensive application of AM-ed metal components in precision engineering scenarios.