Fatigue crack growth rate tests were conducted as a function of temperature, dissolved hydrogen (DH) level, and frequency in a simulated PWR environment. Fatigue crack growth rates increased slightly with increasing temperature in air. However, the fatigue crack growth rate did not change with increasing temperature in PWR water conditions. The DH levels did not affect the measured crack growth rate under the given test conditions. At 316 oC, oxides were observed on the fatigue crack surface, where the size of the oxide particles was about 0.2 μm at 5 ppb. Fatigue crack growth rate increased slightly with decreasing frequency within the frequency range of 0.1 Hz and 10 Hz in PWR water conditions; however, crack growth rate increased considerably at 0.01 Hz. The decrease of the fatigue crack growth rate in PWR water condition is attributed to crack closure resulting from the formation of oxides near the crack tips at a rather fast loading frequency of 10 Hz.

Abstract
 1. 서 론
 2. 실험 방법
  2.1 환경피로시험기 설계조건
  2.2 수화학 루프 및 피로시험장치
  2.3 재료 및 시편
  2.4 피로균열성장률평가
  2.5 피로균열파면 분석
 3. 실험 결과
  3.1 인장특성
  3.2 피로균열성장률
  3.3 피로파면 관찰
 4. 고 찰
  4.1 항복강도의 영향
  4.2 산화물의 영향
  4.3 Frequency의 영향
 5. 결 론
 Acknowledgement
 References

• 민기득(한양대학교 신소재공학부) | Ki-Deuk Min
• 이봉상(한국원자력연구원 재료안전연구부) | Bong-Sang Lee
• 김선진(한양대학교 신소재공학부) | Seon-Jin Kim Corresponding author