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Oxidation and Hydrogen Embrittlement Behavior of Several Additively Manufactured Ni-Based Superalloys

The environmental degradation of additively manufactured Ni-based superalloys (INCONEL® 625 (IN625), Haynes® 282® (H282), and INCONEL® 718 (IN718)), fabricated by laser powder-bed fusion (L-PBF) and fully heat-treated, is being screened for hydrogen service in industrial gas turbines. Oxidation experiments in air, on printed and machined surface conditions at 750 °C for 164, 500, and 2,010 hours revealed thicker oxides for printed conditions for IN625 and H282 and thicker oxides for machined conditions for IN718. The chromium oxide that developed was thickest for H282 and showed higher incorporation of Ni/Fe-based oxides for the as-printed surfaces. Ex-situ hydrogen embrittlement was evaluated by electrochemically charging flat test bars for 72hours in 0.1 M H2SO4 + 1 g/L CH4N2S then slow strain rate tensile testing (0.0039 mm/min) at room temperature. All experienced reduction in strain failure of that lead to a hydrogen embrittlement index of 16%, 18%, and 30% for IN625, H282, and IN718, respectively. Oxidation kinetics showed the highest to smallest oxidation rate: H282, IN625, and IN718. The oxidation rates were higher on the as-printed surfaces for H282 and IN625 but lower for IN718. Topographical imaging of the fracture surfaces showed a 30-100 µm deep embrittlement zone at the surface developed during hydrogen charging, but no significant differences between charged and as-received specimens in the center where ductile dimpling behavior is dominate.
Product Number: 51324-21117-SG
Author: Lucas Teeter; Martin Detrois; Kyle Rozman; Chantal K. Sudbrack
Publication Date: 2024
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