(Digital Presentation) Effects of Surface Finish on the Corrosion Performance of Additively Manufactured Metals

Abstract

Metal additive manufacturing (AM) is becoming a transformative technology in the manufacturing industry. The as-built surfaces produced by metal AM are very different compared to wrought material, typically resulting in very rough surfaces that have different corrosion properties. There are a large number of studies that have attempted to understand the corrosion response of metal AM. However, these studies are typically performed on materials that have been printed on a single machine. As a result, there are significant inconsistencies in the literature due to the high variability in the quality of parts manufactured on different machines. We will present work that compares the corrosion response of AM 316L stainless steel (SS) that has been printed on multiple machines. Our results have shown there is significant variability observed in the corrosion performance of metal AM parts built on different machines and within a single build plate. The observed corrosion performance is likely affected by the stability of the passive film, chemical segregation, and microstructure of the surface. We also propose that surface finishing of AM 316L SS reduces the part-to-part variations observed in the corrosion performance of the material printed on different machines and within a single build plate.This talk will discuss the corrosion properties of AM 316L SS, A20x (AM aluminum alloy), and Ti-6Al-4V parts produced by direct metal laser sintering (DMLS). The majority of our work focused on understanding the susceptibility to localized corrosion of metal additively manufactured materials with respect to build machine, surface roughness, and build angle. As a result, we also examined the corrosion performance of 316L SS built on a single instrument as we varied the build parameters. Conventional electrochemical corrosion experiments were used to characterize corrosion performance, including open circuit potential, potentiostatic electrochemical impedance spectroscopy, and potentiodynamic polarization scans. White light interferometry, optical profilometry, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were utilized to characterize the surface of the samples.