Enhancing Surface Finish of Additively Manufactured 316L Stainless Steel with Pulse/Pulse Reverse Electropolishing

To improve the reliable integration of additively manufactured (AM) metal components, there is an urgent need for surface finishing methods capable of processing rough, as-printed surfaces. We present a new and scalable electropolishing (EP) technique for use on AM 316L stainless steel (SS) that is capable of achieving a surface roughness equivalent to a machined finish, with arithmetic mean heights (S-a) as low as 1.0 mu m. This technique utilizes the sequential application of a new, NaCl/H2O pulse/pulse reverse (P/PR) EP step along with a conventional DC (direct current) EP step, where P/PR expands the capability of EP by removing roughness features > 1 mu m, which has been previously unattainable with DC EP alone without substantial material removal. This is achieved by independently varying pulse parameters, such as pulse width and height, allowing more control over electrodynamic processes at the part-electrolyte interface. Additionally, P/PR EP resulted in higher smoothing efficiency, where a higher degree of smoothing was achieved with less material removal when compared with conventional DC EP alone. This minimizes unwanted change in geometry from excessive metal dissolution.

Automated summary

This paper presents a new and scalable electropolishing technique for surface finishing of additively manufactured stainless steel components. The technique is capable of achieving a machined finish surface roughness by removing roughness features greater than 1 μm through the use of pulse/pulse reverse electropolishing. This technique offers more control over the electrodynamic processes and results in higher smoothing efficiency with less material removal compared to conventional direct current electropolishing alone.