2001 Fiscal Year Final Research Report Summary
Elucidation and modeling oftnecanisms of fatigue fracture in a ultra-fine grained steel
| Project/Area Number |
12650081
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Nagoya University |
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Principal Investigator |
AKINIWA Yashiaki Nagoya Univ., Grad. School ofEng., Assoc. Professor, 工学研究科, 助教授 (00212431)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Hirosi Kobe Univ, Dep. Mech. Eng., Assoc. Professor, 工学部, 助教授 (80236629)
TANAKA Keisuke Nagoya Univ., Grad. School ofEng., Professor, 工学研究科, 教授 (80026244)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Fatigue / Microstructure / Crackinitiation / Crack propagation / Fatigue limit / Slip band |
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| Research Abstract |
The crack propagation rate is lower and the crack opening stress intensity factor (Kop) is higher in ultra fine-grained (UF) specimens than that in edium-grained (M) specimens when compared at the same stress intensity. UF specimens with the largest number of bifurcations and the highest roughness yield the highest Kop.
The distinctive characteristic of fatigue crack initiation in UF specimens is the formation of complex slip deformation. Fatigue cracks initiate from the boundary between the grains with complex slip deformation. Fatigue cracks in M specimens initiates from simple slip lines within the grains.
UF specimens possess not only higher resistance against fatigue crack initiation and the early propagation, but also superior resistance against the propagation of long fatigue cracks.
Propagation and non-propagation of fatigue, cracks was modeled. The slip band interacting with grain boundary was analyzed on the basis of that model. Non-propagating cracks initiated in smooth specimens were classifed into three categories.
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Research Products
(12 results)
