Effect of Initial Surface Features on Laser Polishing of Co-Cr-Mo Alloy Made by Powder-Bed Fusion

Abstract

One of the challenges regarding widespread use of parts created by the powder-bed fusion process is their high surface roughness, which necessitates some type of postbuild finishing process. Laser polishing (i.e., remelting), which uses surface-tension-driven flow to reduce the roughness of irradiated metallic surfaces, is one such potential finishing process. This work examines the effect that surface features on the as-built part have on the performance of continuous-wave laser remelting of Co-Cr-Mo alloy (Celsit 21-P, Stellite 21 equivalent) samples produced by powder-bed fusion manufacturing. This is accomplished by comparison of three-dimensional surface measurements before and after laser remelting using focus-variation microscopy. Engineering models used to simulate the surface profile as a result of laser remelting are also presented. The results from this work provide insight into the fundamental physics occurring during laser remelting on parts made by powder-bed fusion and will aid parameter selection for surface consolidation and smoothing.