Evaluation of Electrochemical and Laser Polishing of Selectively LaserMelted 316L Stainless Steel

• Main Author: Lohser, Julian R
• Format: Others
• Published: DigitalCommons@CalPoly 2018
• Subjects: selective laser melting; laser polishing; electrochemical polishing; lattice; metallurgy; Aerospace Engineering; Materials Science and Engineering
• Online Access: https://digitalcommons.calpoly.edu/theses/1920; https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=3222&context=theses

Selective laser melting has shown incredible growth as a metallic additive manufacturing process in recent years. While it does provide many solutions and new ways to approach challenges, it does not come without issues of its own, namely, surface roughness. In the as-printed state, the surface roughness of selectively laser melted parts is unacceptable for use in engineering applications. Additionally, selective laser melting is used to produce complex geometries with hard to reach features, preventing conventional mechanical polishing from being successful. Therefore, it is necessary to evaluate non-mechanical polishing processes as treatments for surface roughness. In this study, electrochemical and laser polishing were investigated as potential start-to-finish treatments for the surface roughness of selectively laser melted parts. Following this preliminary study, a follow-up study investigating the effect on the mechanical strength of a lattice design that electropolishing would have. Electropolishing was found to significantly reduce the surface roughness of the as-printed part, but not to a usable value. Additionally, electropolishing was found to be unacceptable for use on lattice parts. Laser polishing was found to significantly reduce the surface roughness of the part but had feature size issues preventing a perfectly smooth surface.