Austenitic 304L Stainless Steel (UNS S30403) is used in many industries including but not limited to chemical processing, medical, commercial and domestic applications and is a favorable candidate for additive manufacturing (AM) because of its excellent weldability. In this research, the microstructure and corrosion behavior of AM 304L Stainless Steel (SS) and its wrought counterpart were studied under three conditions: as-fabricated, heat treated at 700°C for 250 hours and heat treated at 800°C for 250 hours. Test coupons were electrochemically characterized in accordance with ASTM G59–97 and ASTM G61–86 protocols in a 3.5 wt% NaCl solution. Microstructural characterization was performed using optical & scanning electron microscopy and energy dispersive spectroscopy (EDS). The results of the electrochemical and microstructural characterization will be presented and discussed.

INTRODUCTION

Laser powder bed fusion (LPBF), often termed selective laser melting (SLM), is a novel additive manufacturing (AM) technique that provides a direct, rapid and cost-effective pathway to fabricate metallic components of complex geometries. During SLM, a laser beam is used to form a solid material by fusing compact metallic powders together layer upon layer. Recent studies on AM alloys have focused mainly on microstructural characterization and mechanical properties; however, the corrosion behavior of these alloys is not well understood.1

Austenitic 304L Stainless Steel (UNS S30403) has a broad range of applications, including but not limited to chemical processing, medical, commercial and domestic applications2 and is a favorable candidate for additive manufacturing (AM) because of its excellent weldability. Wrought 304L SS alloys are heat treated to improve mechanical properties, relieve internal stresses, and homogenize microstructures. However, stainless steel exposed to high temperatures for an extended period can lead to the formation of carbides, which increases its susceptibility to intergranular and pitting attack in corrosive environments.2–4 Newkirk et. al. have found that SLM UNS 30403 alloys exhibit sensitization at heat treating temperatures of 700°C after 150 hours.5–6 Therefore, it is expected that the corrosion resistance of the heat-treated alloys in this study will decrease. Nonetheless, the influence of heat treatment and/or sensitization on the corrosion behavior of SLM fabricated UNS 30403 alloy has not been thoroughly studied.

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