Influence of δ-Ferrite Content on Thermal Aging Induced Mechanical Property Degradation in Cast Stainless Steels

  • Thak Sang ByunEmail author
  • Timothy G. Lach
  • Ying Yang
  • Changheui Jang
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)


Thermal degradation of cast stainless steels was studied to provide an extensive knowledgebase for the assessment of structural integrity during extended operations of reactor coolant systems. The CF3 and CF8 series cast stainless steels with relatively low (5–12%) δ-ferrite contents were thermally aged at 290–400 °C for up to 10,000 h and tested to measure changes in tensile and impact properties. The aging treatments caused significant reduction of tensile ductility, but only slight softening or negligible strength change. The thermal aging also caused significant reduction of upper shelf energy and large shift of ductile-brittle transition temperature (ΔDBTT). The most influential factor in thermal degradation was ferrite content because of the major degradation mechanism occurring in the phase, while the nitrogen and carbon contents caused only weak effects. An integrated model is being developed to correlate the mechanical property changes with microstructural and compositional parameters.


Cast austenitic stainless steels Thermal aging Mechanical properties 



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.


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Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  • Thak Sang Byun
    • 1
    Email author
  • Timothy G. Lach
    • 1
  • Ying Yang
    • 2
  • Changheui Jang
    • 3
  1. 1.Pacific Northwest National LaboratoryRichlandUSA
  2. 2.Oak Ridge National LaboratoryOak RidgeUSA
  3. 3.Korea Advanced Institute of Science & TechnologyDaejeonRepublic of Korea

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