Effect of PBF-SLM Process Parameters on the Electrochemical Behavior of 316L Stainless Steel Parts in Acidic and Chloride Containing Environments

Abstract

The powder bed fusion - selective laser melting (PBF-SLM) process parameters such as laser power and laser scan speeds has a prominent effect of the metallurgical and mechanical properties of the printed parts due to high localized temperatures and high cooling rates associated with the PBF-SLM process. This, in turn, affects the electrochemical and corrosion properties and in effect the service life of the parts. This study investigates the effect of PBF-SLM process parameters; laser power and laser scanning speed on the electrochemical and corrosion properties of 316L stainless steel printed cylindrical parts. The parts were printed using laser powers of 100 and 200 W and the laser scan speeds employed were in the range of 100-3000 mm/s. The electrochemical characterization of the parts involved open circuit potential (OCP) monitoring, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and cyclic polarization (CP) using a three-electrode setup. The test electrolyte used for the electrochemical tests were dilute sulphuric acid (pH~2-3) and 3.5 wt.% NaCl aqueous solution (pH~6.5-7) which represented a wide range of applications. In addition, the metallurgical and microstructural aspects of the parts were studies using optical microscopy (OM), scanning electron microscopy (SEM) and X-Ray diffraction (XRD), whereas the mechanical properties were probed using hardness tests.