Surface Finish Analysis of Gradient Voltage Electrochemical Polishing of 316L Stainless Steel Parts Forming by Laser Powder Bed Fusion.

Laser powder bed fusion (LPBF) of complex-structure 316L stainless steel (316L ss) parts has a wide application prospects in aerospace, biomedical, and defense industry fields. However, the surface roughness (Ra) of the LPBF sample is unsatisfactory due to the process characteristics of layer-by-layer selective melting and cumulative forming, which limits its applications in the engineering field. Herein, a gradient voltage electrochemical polishing strategy is proposed based on the characteristics of electrochemical polishing technology, which can polish complex structures. The mechanisms of polishing process parameters and polishing strategy on the surface finish of LPBF parts are investigated. The gradient voltage polishing strategy is extended to complex structures, and the Ra of the inner surfaces of square and round tubes are successfully reduced to about 1 μm. The gradient electrochemical polishing process for surface finish post-treatment of LPBF parts can broaden the engineering applications of complex-structure metal parts.