Surface treatment of additively manufactured stainless steel 316L lattice structures by plasma electrolytic polishing

Abstract

Additive manufacturing facilitates the production of lattice structures for lightweight and biomedical applications. Typically, as-built structures exhibit rough surfaces, necessitating post-processing to meet functional requirements. Plasma electrolytic polishing (PEP) offers an approach for smoothing surfaces on complex and filigree parts in an environmentally friendly manner. Nonetheless, achieving uniform treatment depends on PEP process parameters and geometric properties of the workpiece.This study investigates capabilities of PEP for treating lattice structures made from 316L stainless steel. Test specimens consisting of face-centered cubic unit cells with an edge length of 3 mm were manufactured by laser-based powder bed fusion.The findings highlight the influence of developed PEP parameters on roughness and dimensional accuracy based on computed tomography scans. Pre-and-post-treatment-comparisons show that smooth, specular outer surfaces can be obtained.Moreover, smoothing of interior surfaces was demonstrated for a relative cell density of 11%. Increasing the cell density to 35% reduces the smoothing effect.