| Abstract Scope |
Alloy 709 (A709) is a high-performance austenitic stainless steel under development for structural applications in advanced nuclear systems due to its superior high-temperature creep strength and promising radiation resistance. While single ion irradiation studies have demonstrated improved swelling resistance in wrought A709 by showing a longer low-swelling regime than 316SS at 575°C, data remains limited, especially for components produced via additive manufacturing (AM). AM introduces distinct dislocation cell structures and grain morphologies that may significantly affect defect evolution.
This research examines the radiation response of A709 produced through both traditional wrought ingot processing and laser powder bed fusion AM. Multiple thermomechanical treatments, including solution annealing, aging, and cold working, are evaluated to understand their influence on microstructural stability. Dual ion irradiations using 9 MeV Fe ions with helium co-implantation were conducted to simulate damage and transmutation gas effects under service conditions relevant to both light water and Generation IV reactor environments. Irradiations were performed at 340°C, 475°C, 575°C, and 675°C, to doses of 2, 10, and 50 dpa. Helium was implanted at 50 appm He/dpa at 340°C and 1 appm He/dpa at higher temperatures to produce conditions relevant for LWRs and fast reactors.
Post-irradiation analysis via TEM, STEM-EDS, and nanoindentation are used to assess void swelling, hardening, dislocation loop formation, and radiation-induced segregation. This work extends understanding beyond prior single ion studies and provides new insights into how AM and thermal processing affect A709’s performance under reactor-relevant conditions. |