Long-term stability of the microstructure of austenitic ODS steel rods produced with a carbon-containing process control agent

JOURNAL OF NUCLEAR MATERIALS

卷:523

Article

Graening, Tim¹  Klimenkov, Michael¹  Rieth, Michael¹  Heintze, Cornelia²  Moeslang, Anton¹ 

[1] Karlsruhe Inst Technol, Inst Appl Mat, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany

[2] Helmholtz Zentrum Dresden Rossendorf, D-01328 Dresden, Germany

关键词: Austenitic ODS steel;    Process control agent;    Long-term annealing;    TEM;    Activation energy;   

DOI  :  10.1016/j.jnucmat.2019.05.060

来源: Elsevier

【 摘 要 】

Austenitic oxide dispersion strengthened (ODS) steel rods containing a carbon-rich process control agent were annealed at 700, 900 and 1100 degrees C for up to 1500 h. The addition of a process control agent was necessary during the mechanical alloying process to achieve a reproducible production process. In this study, the impact of the added carbon-rich process control agent on the microstructure was determined. For that reason, an extruded austenitic ODS steel rod, which designated operation temperature in future power plants is about 700 degrees C and beyond, was annealed and examined. The investigation revealed, that the microstructure remains stable up to 900 degrees C. However, a long-term annealing at 1100 degrees C increased the grain and precipitate size significantly, which resulted in a decline of the mechanical properties. The results indicate, that the introduced carbon and the formation of carbides led to a reduction of the temperature threshold for coarsening of nano-sized oxide precipitate. The direct impact of carbon on the formation of nano-sized precipitates and their behavior at elevated temperature was shown by calculations of the activation energy of precipitate growth. (C) 2019 Elsevier B.V. All rights reserved.

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