Fatigue crack growth retardation of 304 L stainless steel is studied using a neutron diffraction method. Three orthogonal strain components(crack growth, crack opening, and through-thickness direction) are measured in the vicinity of the crack tip along the crack propagation direction. The residual strain profiles (1) at the mid-thickness and (2) at the 1.5 mm away from the mid-thickness of the compact tension(CT) specimen are compared. Residual lattice strains at the 1.5 mm location are slightly higher than at the mid-thickness. The CT specimen is deformed in situ under applied loads, thereby providing evolution of the internal stress fields around the crack tip. A tensile overload results in an increased magnitude of the compressive residual stress field. In the crack growth retardation, it is found that the stresses are dispersed in the crack-wake region, where the highest compressive residual stresses are measured. Our neutron diffraction mapping results reveal that the dominant mechanism is by interrupting the transfer of stress concentration at the crack tip.

Abstract
 1. 서 론
 2. 실험 방법
  2.1 실험 재료
  2.2 피로 실험 조건
  2.3 중성자 회절 시편 제작
  2.4 중성자 회절 실험
 3. 결과 및 고찰
 4. 결 론
 References

• 서석호(충남대학교) | Sukho Seo (Department of Materials Science and Engineering, Chungnam National University)
• E-Wen Huang(국립교통대학교)
• 우완측(한국원자력연구원) | Wanchuck Woo (Neutron Science Division, Korea Atomic Energy Research Institute)
• 이수열(충남대학교) | Soo Yeol Lee (Department of Materials Science and Engineering, Chungnam National University) Corresponding author