| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2015: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
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| Outline of Final Research Achievements |
The 9CrODS steel can be transformed to ferrite during hot-rolling at austenite phase above Ar3 temperature (780°C). It was originally revealed that this dynamic ferrite transformation is not by variant selection rule, but by “massive transformation”. The fcc to bcc structure change by massive transformation can be controlled through sequential displacement of Fe-atoms at the fcc/bcc interfaces rather than long distance diffusion of carbon, which enables to complete the ferrite transformation within short period (0.044 sec) of hot-rolling. The coarse ferrite grain produced by massive transformation contains agglomeration of the fine grains with similar crystal orientation. Tensile strength at 700°C cannot attain the expected one, which is attributed to the selective slip deformation at low-angle grain boundaries inside coarse grain.
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