摘要 Oxide-dispersion strengthened (ODS) ferritic steels are promising candidates for structural applications in the future nuclear reactors. The higher chromium contents of ODS ferritic steels, the better the corrosion resistance will be, which can meet the harsh corrosion environment of the advanced reactors. But the increasing of the Cr content may also lead to the brittleness of the ODS steels when service at high temperatures. In this study, the ODS ferritic steels with different Cr content (12 wt.%, 16 wt.% and 18 wt.%Cr respectively) were fabricated by mechanical alloying, hot isostatic pressing and forging. Mechanical properties and microstructure evolution of the ODS ferritic steels after aging at 753 K for 2000 h were investigated. It is found that both Vickers hardness and yield strength of 18%Cr ODS ferritic steel were strongly increased and the impact energy was decreased after aging at 753 K. In order to explore the reasons for changes in the mechanical properties, the fracture surfaces were characterized by SEM, and microstructures after aging were observed by TEM. The impact fracture of 18%Cr ODS ferritic steel belongs to quasi-cleavage facture, which is consistent with its very low impact energy. The grain size and dispersed oxide particles of different ODS steels are very stable. M23C6 carbide and M2C carbide have been found in 12%Cr ODS steel and 16%Cr ODS steels respectively.
Abstract：Oxide-dispersion strengthened (ODS) ferritic steels are promising candidates for structural applications in the future nuclear reactors. The higher chromium contents of ODS ferritic steels, the better the corrosion resistance will be, which can meet the harsh corrosion environment of the advanced reactors. But the increasing of the Cr content may also lead to the brittleness of the ODS steels when service at high temperatures. In this study, the ODS ferritic steels with different Cr content (12 wt.%, 16 wt.% and 18 wt.%Cr respectively) were fabricated by mechanical alloying, hot isostatic pressing and forging. Mechanical properties and microstructure evolution of the ODS ferritic steels after aging at 753 K for 2000 h were investigated. It is found that both Vickers hardness and yield strength of 18%Cr ODS ferritic steel were strongly increased and the impact energy was decreased after aging at 753 K. In order to explore the reasons for changes in the mechanical properties, the fracture surfaces were characterized by SEM, and microstructures after aging were observed by TEM. The impact fracture of 18%Cr ODS ferritic steel belongs to quasi-cleavage facture, which is consistent with its very low impact energy. The grain size and dispersed oxide particles of different ODS steels are very stable. M23C6 carbide and M2C carbide have been found in 12%Cr ODS steel and 16%Cr ODS steels respectively.
ZHANGJIAN -Zhou,SHAOFU -Li,HAODONG -Jia. Long-term thermal-aging stability of oxide-dispersion-strengthened ferritic steels at 753 K[J]. Journal of Iron and Steel Research International, 2018, 25(7): 753-784.
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2018, Vol. 25 
