G91강 저주파 피로균열 성장에 미치는 온도와 응력비의 영향 (Effects of Temperature and Stress Ratio on Low-Cycle Fatigue Crack Growth of G91 Steel)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 50권 / 4호 / 271 ~ 279페이지
· 저자명 : 김종범, 황수경, 김범준, 이종훈, 박창규, 이형연, 김문기, 임병수

초록

9-12% Cr steels have been used in thermal power plants which repeat start and stop operations.
Major factors of fatigue life are temperature, frequency, stress ratio, holding time, microstructure, and environment. Normally, fatigue life decreases at high temperature, low frequency, high stress ratio, and long holding time conditions. A Mod.9Cr-1Mo steel, called G91, was developed at ORNL (Oak Ridge National Laboratory, USA) and was adopted as a high-temperature structural material in the ASME Code in 2004.
However, its low-cycle fatigue and fatigue crack growth characteristics have been rarely studied. In this work,we have investigated the low-cycle fatigue crack growth behaviors of G91 steel under various test conditions in terms of temperature and stress ratio. As temperature and stress ratio increase, the crack growth rate becomes faster and striation distance also increases. On the other hand, the number of branch cracks decreases.

영어초록

9-12% Cr steels have been used in thermal power plants which repeat start and stop operations.
Major factors of fatigue life are temperature, frequency, stress ratio, holding time, microstructure, and environment. Normally, fatigue life decreases at high temperature, low frequency, high stress ratio, and long holding time conditions. A Mod.9Cr-1Mo steel, called G91, was developed at ORNL (Oak Ridge National Laboratory, USA) and was adopted as a high-temperature structural material in the ASME Code in 2004.
However, its low-cycle fatigue and fatigue crack growth characteristics have been rarely studied. In this work,we have investigated the low-cycle fatigue crack growth behaviors of G91 steel under various test conditions in terms of temperature and stress ratio. As temperature and stress ratio increase, the crack growth rate becomes faster and striation distance also increases. On the other hand, the number of branch cracks decreases.

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