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Microstructure and Deformation Behavior of Thermally Aged Cast Austenitic Stainless Steels

  • Y. ChenEmail author
  • C. Xu
  • X. Zhang
  • W.-Y. Chen
  • J.-S. Park
  • J. Almer
  • M. Li
  • Z. Li
  • Y. Yang
  • A. S. Rao
  • B. Alexandreanu
  • K. Natesan
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

Cast austenitic stainless steels (CASS) consist of a dual-phase microstructure of delta ferrite and austenite. The ferrite phase is critical for the service performance of CASS alloys, but can also undergo significant microstructural changes at elevated temperatures, leading to severe embrittlement. To understand thermal aging embrittlement, fracture toughness J-R curve tests were performed on unaged and aged CF8 specimens at 315 ℃. The microstructure of CF8 was also examined before and after thermal aging with transmission electron microscopy and atom probe tomography. While no microstructural change was observed in the austenite after thermal aging, a high density of G-phase precipitates and a phase separation of alpha/alpha prime were detected in ferrite. To study the deformation behavior, tensile tests were performed at room temperature with in situ wide-angle X-ray scattering measurements. The differences in lattice strains between ferrite and austenite were much higher in the aged than in the unaged samples, suggesting a higher degree of incompatible deformation between ferrite and austenite in the aged samples.

Keywords

Cast austenitic stainless steels Thermal aging embrittlement Fracture toughness Microstructural characterization Wide-angle X-ray scattering 

Notes

Acknowledgements

This work is sponsored by the U.S. Nuclear Regulatory Commission, under Job Code V6380, and by the U.S. Department of Energy, under contract # DE-AC02-06CH11357. The work at the IVEM and CAES was supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  • Y. Chen
    • 1
    Email author
  • C. Xu
    • 2
  • X. Zhang
    • 1
  • W.-Y. Chen
    • 1
  • J.-S. Park
    • 1
  • J. Almer
    • 1
  • M. Li
    • 1
  • Z. Li
    • 2
  • Y. Yang
    • 2
  • A. S. Rao
    • 3
  • B. Alexandreanu
    • 1
  • K. Natesan
    • 1
  1. 1.Argonne National LaboratoryLemontUSA
  2. 2.University of FloridaGainesvilleUSA
  3. 3.US Nuclear Regulatory CommissionRockvilleUSA

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