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

Korean Society of Pressure Vessels and Piping (한국압력기기공학회)
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Influence of dynamic strain aging on material strength behavior of virgin and service-exposed Gr.91 Steel

신재 및 가동이력 Gr.91강의 재료강도 거동에 미치는 동적변형시효의 영향

  • Ki-Ean Nam ;
  • Hyeong-Yeon Lee ;
  • Jae-Hyuk Eoh ;
  • Hyungmo Kim ;
  • Hyun-Uk Hong
  • 남기언 (한국원자력연구원) ;
  • 이형연 (한국원자력연구원) ;
  • 어재혁 (한국원자력연구원) ;
  • 김형모 (경상국립대학교) ;
  • 홍현욱 (창원대학교)
  • Received : 2024.05.31
  • Accepted : 2024.06.12
  • Published : 2024.06.30
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Abstract

This study investigates the effects of temperatures and strain rates on the strength and ductility of Gr.91 (ASME Grade 91) steel which is widely being used as a heat-resistant material in Generation IV nuclear and super critical thermal power plants. The tensile behavior of modified 9Cr-1Mo (Gr.91) steel was studied for the three strain rates of 6.67×10-5/s, 6.67×10-4/s and 6.67×10-3/s over the temperature range from room temperature (RT) to 650℃. Experimental results showed that at specific combinations of temperatures (300~400℃) and strain rates, serrations appeared in the stress-strain curves. Concurrently, abnormal behaviors such as a plateau in yield strength and tensile strength, a minimum in ductility and negative strain rate sensitivity were observed. These phenomena were analyzed as significant characteristics of dynamic strain aging (DSA). Since this abnormal behavior in Gr.91 steel affects the material strength, it is judged that a correlation analysis between DSA and material strength should be crucial in the design and integrity evaluation of Gr. 91 steel pressure vessel and piping subjected to high-temperature loading.

Keywords

Acknowledgement

본 연구는 한국연구재단(2021R1I1 A2057941, 2021K1A3A1A 78097845 and 2021M2E2A2081063) 및 국가과학기술연구회(CAP20032-100)의 지원을 받아 수행됨.

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