The influence of thermomechanical treatment on special features of the deformed microstructure of the EK-181 ferritic-martensitic steel
Ferritic-martensitic steels with a chromium content of 9–12 % are currently considered as the promising structural materials for nuclear power. Interest in steels of this class is caused by their higher resistance to radiation swelling compared with austenitic steels used in the existing fission reactors. The operating temperature range of these steels is limited from below by their tendency to low-temperature embrittlement (cold fracture) under the radiation influences, and from above – by the long-term strength level (heat resistance). The authors studied the features of the microstructure of 12 % Cr ferritic-martensitic EK-181 steel near the neck of the samples deformed by tension at T=20 °С and within the range of temperatures close to the operating temperatures of a nuclear reactor (T=650 and T=720 °C). The authors carried out the comparative study of the materials processed by two methods: traditional and high-temperature treatment. The study showed that plastic deformation at T=20 °C after two treatments is similar in quality and leads to curvature and fragmentation of martensitic lamella, as well as to the formation of new low-angle boundaries. Deformation near the operating temperature range (T=650 and T=720 °C) contributes to the development of the processes of dynamic polygonization, recrystallization, increasing the density, and the size of carbide particles. After high-temperature thermomechanical treatment, these processes are less intensive compared to the state after traditional thermal treatment. After high-temperature thermomechanical treatment, EK-181 steel has an increased level of strength and has a higher resistance to plastic deformation compared to the state after traditional treatment. It is related to the high density of vanadium carbonitride nano-particles V(C, N) and the increased dislocation density after high-temperature thermomechanical treatment.
Tan L., Hoelzer D.T., Busby J.T., Sokolov M.A., Klueh R.L. Microstructure control for high strength 9 % Cr ferritic-martensitic steels. Journal of Nuclear Materials, 2012, vol. 422, no. 1-3, pp. 45–50.
Huang Q., Baluc N., Dai Y., Jitsukawa S., Kimura A., Konys J., Kurtz R.J., Lindau R., Muroga T., Odette G.R., Raj B., Stoller R.E., Tan L., Tanigawa H., Tavassoli A.A., Yamamoto T., Wan F., Wu Y. Recent progress of R&D activities on reduced activation ferritic/martensitic steels. Journal of Nuclear Materials, 2013, vol. 442, no. 1-3, pp. S2–S8.
Leonteva-Smirnova M.V., Ioltukhovskiy A.G., Arutiunova G.A., Tselischev A.V., Chernov V.M. Investigation of heat treatment conditions on the structure of 12% chromium reduced activation steels. Journal of Nuclear Materials, 2002, vol. 307, no. 311, pp. 466–470.
Lanskaya K.A. Vysokokhromistye zharoprochnye stali [High-Chromium heat-resistant steels]. Moscow, Metallurgiya Publ., 1967. 216 p.
Klueh R.L., Nelson A.T. Ferritic/martensitic steels for next-generation reactors. Journal of Nuclear Materials, 2007, vol. 371, no. 1-3, pp. 37–52.
Almaeva K.V., Polekhina N.A., Litovchenko I.Yu. A comparative investigation of mechanical properties of the ferritic-martensitic steel EK-181 in the temperature range 700–800 °C after high-temperature thermomechanical and traditional heat treatments. AIP Conference Proceedings, 2018, vol. 2051, article number 020009.
Polekhina N.A., Litovchenko I.Y., Tyumentsev A.N., Kravchenko D.A., Chernov V.M., Leontyeva-Smirnova M.V. Effect of High-Temperature Thermomechanical Treatment in the Austenite Region on Microstructure and Mechanical Properties of Low-Activated 12% Chromium Ferritic-Martensitic Steel EK-181. Technical Physics, 2017, vol. 62, no. 5, pp. 736–740.
Mao C., Liu C., Yu L., Li H., Liu Y. Mechanical properties and tensile deformation behavior of a reduced activated ferritic-martensitic (RAFM) steel at elevated temperatures. Materials Science and Engineering A, 2018, vol. 725, pp. 283–289.
Vivas J., Capdevila C., Altstadt E., Houska M., San-Martin D. Importance of austenitization temperature and ausforming on creep strength in 9Cr ferritic/martensitic steel. Scripta Materialia, 2018, vol. 153, pp. 14–18.
Prakash P., Vanaja J., Rao Palaparti D.P., Prasad Reddy G.V., Laha K., Nageswara Rao G.V.S. Tensile flow and work hardening behavior of reduced activation ferritic martensitic steel subjected to thermo-mechanical treatment. Journal of nuclear materials, 2019, vol. 520, pp. 19–26.
Li X., Li X., Schonecker S., Li R. Understanding the mechanical properties of reduced activation steels. Materials and design, 2018, vol. 146, pp. 260–272.
Klueh R.L., Hashimoto N., Maziasz P.J. New nano-particle-strengthened ferritic/martensitic steels by conventional thermo-mechanical treatment. Journal of Nuclear Materials, 2007, vol. 367-370, pp. 48–53.
Polekhina N.A., Litovchenko I.Yu., Tyumentsev A.N., Akkuzin S.A., Chernov V.M., Leonteva-Smirnova M.V. Temperature dependence of mechanical properties and fracture features of low-activation ferritic-martencitic steel ek-181 in the temperature range from -196 to 720. Voprosy atomnoy nauki i tekhniki. Seriya: Termoyadernyy sintez, 2017, vol. 40, no. 4, pp. 92–102.
Hollner S., Fournier B., Le Pendu J., Cozzika T., Tournie I., Brachet J.-C., Pineau A. High-temperature mechanical properties improvement on modified 9Cr-1Mo martensitic steel through thermomechanical treatments. Journal of Nuclear Materials, 2010, vol. 405, no. 2, pp. 101–108.
Hollner S., Piozin E., Mayr P., Caës C., Tournié I., Pineau A., Fournier B. Characterization of a boron alloyed 9Cr3W3CoVNbBN steel and further improvement of its high-temperature mechanical properties by thermomechanical treatments. Journal of Nuclear Materials, 2013, vol. 441, no. 1-3, pp. 15–23.
Hoffman J., Rieth M., Commin L., Fernandez P., Roldan M. Improvement of reduced activation 9%Cr steels by ausforming. Nuclear Materials and Energy, 2016, vol. 6, pp. 12–17.
Polekhina N.A., Almaeva K.V., Litovchenko I.Y. Mechanical properties and fracture of heat-resistant ferritic-martensitic steels EK-181, ChS-139 and EP-823 at the temperatures from –196 to 720 °C. AIP Conference Proceedings, 2018, vol. 2051, article number 020242.
Lindau R., Schirra M. First results on the characterization of the reduced-activation-ferritic-martensitic steel EUROFER. Fusion Engineering and design, 2001, no. 58-59, pp. 781–785.
Panin A.V., Chernov V.M., Leontieva-Smirnova M.V., Melnikova Ye.A. Strengthening of the RAFMS RUSFER-EK-181 through nanostructuring surface layers. Journal of Nuclear Materials, 2009, vol. 386-388, no. C, pp. 466–470.
Chernov V.M., Moroz K.A., Kardashev B.K. Cold brittleness and fracture of metals with various crystal lattices: Dislocation mechanisms. Technical Physics. The Russian Journal of Applied Physics, 2016, vol. 61, no. 7, pp. 1015–1022.
The authors who publish their manuscripts in “Vektor Nauki of Togliatti State University” Journal agree that:
- When submitting a manuscript to the Editors of “Vektor Nauki of Togliatti State University” Journal, the author accepts that the Editors have the exclusive property rights for the paper use (material submitted to the Editors including such protected by the copyright law objects as figures, charts, tables, etc.), including the rights for reproduction in print and on the Internet; distribution; translation of the materials into English.
- The author guarantees that (s)he has exclusive copyright for the material submitted to the Editors. Shall this guarantee be violated and shall the Editors receive any complaints or claims as a result, the Author shall settle all claims and complaints at his/her own and at his/her expense. The Editors shall not be held liable to a third party for violation of the guarantees given by the Author.
- The Author shall retain the right to use his/her published material, its fragments and paragraphs for personal and teaching purposes. Copying the materials published in the journal can only be allowed to other individuals or legal entities by a written consent from the Editors with a reference to the particular issue (year of publishing) in which the material was published.