Microstructural Analysis of Additively Manufactured Corrosion Resistant Duplex Stainless Steel Clads on Carbon Steel Substrate Pratik Murkute 1 , Somayeh Pasebani 2,3 and O. Burkan Isgor 4* 1. Materials Science, MIME, Oregon State University, Corvallis, Oregon, USA. 2. Manufacturing Engineering, MIME, Oregon State University, Corvallis, Oregon, USA. 3. Advanced Technology and Manufacturing Institute (ATAMI), Corvallis, Oregon, USA. 4. School of Civil and Construction Engineering, Oregon State University, Corvallis, Oregon, USA * Corresponding author: Burkan.isgor@oregonstate.edu The low carbon steel finds extensive applications due to high strength to cost ratio; however, due to its low corrosion resistance, its service life is significantly reduced. On the contrary, the super duplex stainless steels (SDSS) manifests superior pitting corrosion resistance (PREN >40)[1] in chloride containing environments resulting in excellent service life. However, high SDSS cost limits its applicability. Cladding corrosion resistant SDSS on low carbon steel (LCS) substrate is a plausible solution to reduce the material costs while maintaining the performance level and the service life of the component. In this research, additive manufacturing technique; powder bed fusion- selective laser melting (PBF-SLM) was used to clad SDSS on LCS substrate. This study investigates the metallurgical aspects of the PBF-SLM clads using the elemental area and line mapping modes of scanning electron microscopy- energy dispersive x-ray spectroscopy (SEM-EDS). In this study, the LCS substrate was used in plate form (3 x 3 x 1/8 in 3 ) (Fig.1b) and Sandvik’s gas atomized SDSS powder feedstock [15-45 μm (D50=30 μm)] (Fig. 1c) was used as a cladding material. Energy density (Fig. 1a) is the governing parameter for the clads. For all clads, PBF-SLM parameters such as a laser power (P) of 200 W, hatch spacing (h=30 μm), hatch orientation (90 o ), powder layer thickness (d=50 μm), and total thickness (T=500 μm) were maintained constant, and all clads were produced at a laser scan speed ranging from 100-1000 mm/s, resulting in volumetric energy density (VED: J/mm 3 ) in the range of 133-1333 J/mm 3 . After laser melting, the samples were prepared for EDS analysis using metallographic preparation methods. The EDS line scans and area mapping were performed across the clad-substrate (SDSS-LCS) interface for elemental analysis and area maps (Fig. 2a) show the contrast observed due to atomic weight difference for Cr, Ni, and Fe elements. This contrast is due to the difference of the elemental atomic weight in Cr, Ni-rich SDSS clad layer and Cr, Ni-deficient LCS substrate. Furthermore, the back scattered emission (BSE) imaging mode of SEM was used to investigate the clad thickness measurements. It was observed that increasing energy density had a positive impact of the clad thicknesses. The maximum average clad thickness of 65.8 μm was achieved at the highest VED of 1333 J/mm 3 , whereas the lowest VED of 133 J/mm 3 resulted in the thinnest clads. Figure 2(b) illustrates the EDS line scans for Cr content in SDSS clads at different energy density. It was observed that the clads had lower chromium content than the feedstock powder (~25 wt. %) due to evaporative losses experienced during laser melting process. Furthermore, at a higher energy density of 1333 J/mm 3 , the Cr content in the clad dropped to about 13 wt.%, and increasingly higher Cr contents were measured in clads region with decreasing energy density, e.g., at E=133 J/mm 3 , clad showed Cr content of ~24.8 wt. % which was very close to the SDSS feedstock powder composition. Albeit the Cr 2570 doi:10.1017/S1431927619013588 Microsc. Microanal. 25 (Suppl 2), 2019 © Microscopy Society of America 2019 https://doi.org/10.1017/S1431927619013588 Downloaded from https://www.cambridge.org/core. IP address: 54.163.42.124, on 24 May 2020 at 02:49:58, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms.