Analysis of Fatigue Fracture by Dislocation Structure Observation using ECCI Method

2014 Fiscal Year Final Research Report

• Project/Area Number: 24656091
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Materials/Mechanics of materials
• Research Institution: Osaka City University
• Principal Investigator: KANEKO Yoshihisa 大阪市立大学, 大学院工学研究科, 教授 (40283098)
• Co-Investigator(Kenkyū-buntansha): HASHIMOTO Satoshi 大阪市立大学, 大学院工学研究科, 名誉教授 (50127122)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 疲労 / 走査型電子顕微鏡 / 転位 / EBSD / 格子回転

Outline of Final Research Achievements

Because cyclic deformation is localized around a tip of fatigue crack, self-organized dislocation structure and lattice distortion are produced below a fracture surface, as signatures of fatigue process. In the present study, we investigates the dislocation structure and the lattice rotation with the ECCI and EBSD techniques. In the experiments employing copper single crystals, we observed the concentric distributions of the vein and the cell dislocations structures, which were affected by the distance from fracture surface, the stress intensity factor range and the crystallographic orientation. In polycrystalline copper, the EBSD analyses revealed that the local lattice rotation near the fracture surface depended on the stress intensity factor range. These results suggest a possibility that a fracture process can be estimated by the microstructural observation near the fracture surface.

Free Research Field

材料工学