Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging

Timothy G. Lach; Thak Sang Byun

doi:10.1007/978-3-319-68454-3_49

Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

Abstract

Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M₂₃C₆ carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.

Original language	English
Title of host publication	Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors
Editors	Michael Wright, Denise Paraventi, John H. Jackson
Publisher	Springer International Publishing
Pages	643-652
Number of pages	10
ISBN (Print)	9783319684536
DOIs	https://doi.org/10.1007/978-3-319-68454-3_49
State	Published - 2018
Externally published	Yes
Event	18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, 2017 - Portland, United States Duration: Aug 13 2017 → Aug 17 2017

Publication series

Name	Minerals, Metals and Materials Series
Volume	Part F11
ISSN (Print)	2367-1181
ISSN (Electronic)	2367-1696

Conference

Conference	18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, 2017
Country/Territory	United States
City	Portland
Period	08/13/17 → 08/17/17

Funding

Acknowledgements This research was sponsored by U.S. Department of Energy/Office of Nuclear Energy through Light Water Reactor Sustainability R&D Program and International Nuclear Energy Research Initiative (I-NERI) Program. Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract No. DEAC05-76RL01830. APT and FIB/SEM were performed at PNNL’s Environmental Molecular Sciences Laboratory, a Department of Energy—Office of Biological & Environmental Research national scientific user facility.

Funders	Funder number
I-NERI
Light Water Reactor Sustainability R&D Program and International Nuclear Energy Research Initiative
U.S. Department of Energy	DEAC05-76RL01830
Battelle
Office of Nuclear Energy

Keywords

Duplex stainless steel
G-phase precipitation
Solute segregation
Spinodal decomposition
Thermal aging degradation

Access to Document

10.1007/978-3-319-68454-3_49

Cite this

Lach, T. G., & Byun, T. S. (2018). Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. In M. Wright, D. Paraventi, & J. H. Jackson (Eds.), Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors (pp. 643-652). (Minerals, Metals and Materials Series; Vol. Part F11). Springer International Publishing. https://doi.org/10.1007/978-3-319-68454-3_49

Lach, Timothy G. ; Byun, Thak Sang. / Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. editor / Michael Wright ; Denise Paraventi ; John H. Jackson. Springer International Publishing, 2018. pp. 643-652 (Minerals, Metals and Materials Series).

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abstract = "Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M23C6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.",

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Lach, TG & Byun, TS 2018, Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. in M Wright, D Paraventi & JH Jackson (eds), Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Minerals, Metals and Materials Series, vol. Part F11, Springer International Publishing, pp. 643-652, 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, 2017, Portland, United States, 08/13/17. https://doi.org/10.1007/978-3-319-68454-3_49

Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. / Lach, Timothy G.; Byun, Thak Sang.
Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. ed. / Michael Wright; Denise Paraventi; John H. Jackson. Springer International Publishing, 2018. p. 643-652 (Minerals, Metals and Materials Series; Vol. Part F11).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

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AU - Lach, Timothy G.

AU - Byun, Thak Sang

N1 - Publisher Copyright: © The Minerals, Metals & Materials Society 2018.

PY - 2018

Y1 - 2018

N2 - Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M23C6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.

AB - Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M23C6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.

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Lach TG , Byun TS. Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. In Wright M, Paraventi D, Jackson JH, editors, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Springer International Publishing. 2018. p. 643-652. (Minerals, Metals and Materials Series). doi: 10.1007/978-3-319-68454-3_49

Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging

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