2003 Fiscal Year Final Research Report Summary
Neutron diffraction and surface morhology observation of ultra-fine grained materials
| Project/Area Number |
13450283
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Ibaraki University |
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Principal Investigator |
TOMOTA Yo IBARAKI Univ., College of Engineering, Professor, 工学部, 教授 (90007782)
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| Co-Investigator(Kenkyū-buntansha) |
鈴木 徹也 茨城大学, 工学部, 講師 (70261740)
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| Project Period (FY) |
2001 – 2003
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| Keywords | neutron diffraction / nano-structure / pearlite / cementite dissolution / ferrite / strength / phase stress / residual stress |
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| Research Abstract |
Ultra-fine grained materials were prepared through themo-mechanical heat treatment and their microstructures and tensile behavior were examined by using neutron diffraction and laser conforcal microscopy. The materials studied include (1)pearlite, (2)ferrite and (3)severely drawn ferrite or pearlite steel wires.
The internal stresses, i.e., phase stress, block stress and lamellar stress are generated by multi-scale inhomogeneity in plastic flow. Leading to high work-hardening. The stress in cementite plates embedded into the ferrite matrix was determined approximately 5GPa when a pearlite steel is subjected to the applied stress of 1.6GPa.
A ferrite steel consisting of submicron meters ferrite and cementite particles exhibits a high strength but little work-hardening. Using tensile and compression tests and surface observations, the plastic instability in the early stage of tensile deformation was made clear.
Heavily drawn ferrite steel was found to show continuous recrystalisation during plastic deformation and hence only grain growth was observed by annealing. The strength of such nano-grain sized specimen show 1.4GPa. In case of peralite steel, cementite plates dissolve during drawing and exhibited the tensile strength as high as 4GPa. The elastic behavior was revealed nonlinear at the higher stress regime by insitu neutron diffraction during tensile loading.
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Research Products
(6 results)
