Oxide-Dispersion-Strengthened Steels Produced via Gas Atomization Reaction Synthesis of Powders and Consolidated with Laser Powder Bed Fusion

Oxide-Dispersion-Strengthening is a method of interest for producing steel more suitable for structural applications in nuclear power plants, but can be difficult to manufacture. The Ti-Y oxides particles improve elevated temperature strength and creep resistance and lower void swelling from neutron irradiation, while the iron matrix and chromium result in a high thermal conductivity, low thermal expansion, and corrosion resistance against exposure to coolants [1] [2] [3] [4] [5]. The largest benefit of ODS steels in comparison to other materials are the elevated temperature mechanical properties which highly depend on the oxides present. A higher oxide density, and smaller size distribution results in better mechanical properties at elevated temperatures [4]. Steel powders with additions of yttrium, titanium and oxygen were obtained by gas atomization reaction synthesis (GARS) and printed via Laser-Powder-Bed-Fusion (L-PBF) additive manufacturing. Benefits from these processes include being able to introduce controlled amounts of oxygen during powder formations and consolidation of powders, having the capability to produce near net shape parts, and having the ability to influence cooling behavior by adjusting raster patterns. There are many process variables that can influence the distribution of oxides, which directly influence mechanical properties, so samples printed in argon atmospheres containing varying amounts of oxygen were produced, and focused ion beam (FIB) lift-outs were characterized via Transmission Electron Microscopy. The impact of oxygen content of the printing atmosphere at selected printing parameters on oxide size distribution and overall density are discussed.