2016 Fiscal Year Final Research Report
Processing of ultrafine grained materials free of residual dislocations by SPD and annealling
| Project/Area Number |
26420748
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Material processing/Microstructural control engineering
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| Research Institution | Doshisha University |
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Principal Investigator |
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| Project Period (FY) |
2014-04-01 – 2017-03-31
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| Keywords | Grain boundary / SCC / Non-equilibrium GB |
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| Outline of Final Research Achievements |
In this work, the effect of grain size in the sub-micron range on the SCC of Cu-10wt%Zn alloys is investigated using constant load tests in ammonia vapor. The grain size is systematically controlled from 0.12 μm to 40 μm by either cold-rolling or ECAP, followed by annealing. The specimens are kept in tension until fracture under a constant stress ammonia vapor.
The time to fracture has increased with decreasing grain size reaching 1 μm, but decrease with further decreasing grain size into the sub-micron range. In other words, there is a critical grain size that the susceptibility to SCC changes. Sensitivity to IGSCC is associated with GB energy. Non-equilibrium GB have higher GB energy than equilibrium GB because they contain extrinsic dislocation in grains induced by severe plastic deformation (SPD) process, and possibly exhibit GB sliding. This inverse trend in the sub-micron range is discussed in terms of a SPD-induced ultrafine grain (UFG) microstructure
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| Free Research Field |
組織制御、金属工学
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