Directional reflectance microscopy of stainless steel

• Main Author: Cheong, Wai Leong
• Other Authors: Matteo Seita
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Aeronautical engineering; Engineering::Materials::Metallic materials
• Online Access: https://hdl.handle.net/10356/142053
• Institution: Nanyang Technological University

The usage of stainless steel and its alloys, particularly SS 316L, over the years are consistently high due to the desirable combination of its high corrosion resistance and ease of fabrication. With these properties, it is without doubt that SS316L is selected for use in the development in metal 3D printing. Because of this, it has attracted the use of directional reflectance microscopy (DRM), an advanced optical microscopy technique which measures grain reflectance in optical micrographs, to characterize the material. DRM is a relatively new optical microscopy based characterization technique, developed in 2017. Hence, the aim of this study is to investigate the suitability of DRM for the characterization of SS 316L. The provided 3D printed sample’s cross-sectional surface was grinded, polished and prepared to a mirror finish and chemically etched in Marble's Reagent. The effect of the etchant was observed from the visible contrast of the grains presented in optical micrographs for evaluation. Next, the reflectance of selected grains are visualized in the form of directional reflectance profiles (DRP), which is obtained from a custom coded MATLAB program.