Transactions of the Korean Society of Pressure Vessels and Piping (한국압력기기공학회 논문집)

Korean Society of Pressure Vessels and Piping (한국압력기기공학회)
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Analysis of Activation Energy of Thermal Aging Embrittlement in Cast Austenite Stainless Steels

주조 오스테나이트 스테인리스강의 열취화 활성화에너지 분석

  • 이경근 (한국원자력연구원 재료안전기술연구부) ;
  • 홍석민 (한국원자력연구원 재료안전기술연구부) ;
  • 김지수 (한국원자력연구원 재료안전기술연구부) ;
  • 안동현 (한국원자력연구원 재료안전기술연구부) ;
  • 김종민 (한국원자력연구원 재료안전기술연구부)
  • Received : 2024.05.31
  • Accepted : 2024.06.11
  • Published : 2024.06.30
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Abstract

Cast austenitic stainless steels (CASS) and austenitic stainless steel weldments with a ferrite-austenite duplex structure are widely used in nuclear power plants, incorporating ferrite phase to enhance strength, stress relief, and corrosion resistance. Thermal aging at 290-325℃ can induce embrittlement, primarily due to spinodal decomposition and G-phase precipitation in the ferrite phase. This study evaluates the effects of thermal aging by collecting and analyzing various mechanical properties, such as Charpy impact energy, ferrite microhardness, and tensile strength, from various literature sources. Different model expressions, including hyperbolic tangent and phase transformation equations, are applied to calculate activation energy (Q) of room-temperature impact energies, and the results are compared. Additionally, predictive models for Q based on material composition are evaluated, and the potential of machine learning techniques for improving prediction accuracy is explored. The study also examines the use of ferrite microhardness and tensile strength in calculating Q and assessing thermal embrittlement. The findings provide insights for developing advanced prediction models for the thermal embrittlement behavior of CASS and the weldments of austenitic steels, contributing to the safety and reliability of nuclear power plant components.

Keywords

Acknowledgement

이 논문은 정부(과학기술정보통신부)의 재원으로 한국연구재단의 지원을 받아 수행된 연구임 (RS-2022-00144399).

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