Effect of Thermal Aging on Microstructural Evolution in Ferrite of Duplex Stainless Steel in Nuclear Power Plant Applications

摘要

Z3CN20-09M duplex steels are thermally aged at 400℃ for up to 20,000 h. The mechanical properties have been characterized by Charpy V-notch impact test and Nano-indentation test. It is found that the nano-hardness in ferrite increases and the impact toughness decreases with aging time. Moreover, the distribution of alloying elements has been carefully characterized using atom probe tomography (APT). The results indicate that the ferrite decomposes into Cr-rich a' and Cr-lean a phase during the thermal aging and Ni-rich G-phase forms in ferrite. The effect of aging time on solute nanostructure has been investigated systematically.