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- Sawada Kota
- National Institute for Materials Science
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- Sekido Kaoru
- National Institute for Materials Science
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- Kimura Kazuhiro
- National Institute for Materials Science
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- Arisue Ko
- Mitsubishi Heavy Industries, Ltd.
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- Honda Masaki
- Mitsubishi Heavy Industries, Ltd.
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- Komai Nobuyoshi
- Mitsubishi Heavy Industries, Ltd.
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- Fukuzawa Norihide
- Hitachi Metals Ltd.
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- Ueno Tomonori
- Hitachi Metals Ltd.
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- Shimohata Nobuaki
- Electric Power Development Co., Ltd.
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- Nakatomi Hitoshi
- Electric Power Development Co., Ltd.
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- Takagi Kenji
- Electric Power Development Co., Ltd.
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- Kimura Takahiro
- IHI Corporation
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- Nomura Kyohei
- IHI Corporation
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- Kubushiro Keiji
- IHI Corporation
抄録
<p>To clarify the cause of heat-to-heat variation in the creep strength of Grade T91 steels, the influence of the initial microstructure on creep strength was investigated. The distribution of chromium concentration considered to be remaining segregation was observed as corresponding to lamellar contrasts parallel to the longitudinal direction of the boiler tube. Standard deviation (SD) of ΔCr was employed as an indicator of the degree of segregation, and a good correlation was found between the SD of ΔCr and the creep rupture life at 650°C. Remaining segregation was reduced by renormalizing heat treatment at 1200°C instead of 1250°C. The creep rupture life of steel subjected to renormalizing heat treatment at 1200°C and tempering at 760°C, followed by normalizing and tempering under standard heat treatment conditions for Grade T91 steel, was prolonged by a factor of 2.3–2.8. The strengthening effect of renormalizing at 1200°C to reduce the remaining segregation was confirmed by creep tests up to about 10000 h at 600°C and 650°C. Decreases in the number density of M23C6 carbide particles, length of high-angle boundaries and average KAM values during creep exposure are promoted by the presence of remaining segregation. Since diffusion is enhanced by the concentration gradient of elements, degradation due to microstructural change is promoted by the presence of remaining segregation. Segregation should be reduced to obtain high creep strength with homogenized concentration of chemical composition.</p>
収録刊行物
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- ISIJ International
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ISIJ International 60 (2), 382-391, 2020-02-15
一般社団法人 日本鉄鋼協会
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詳細情報 詳細情報について
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- CRID
- 1390846609805892096
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- NII論文ID
- 130007799309
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- ISSN
- 13475460
- 09151559
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- Crossref
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可