Development of Ultra High-strength TRIP-aided Forging Steels by Ausforming-austempering Process
| Project/Area Number |
17560631
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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 |
Material processing/treatments
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| Research Institution | Shinshu University |
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Principal Investigator |
SUGIMOTO Koh-ichi Shinshu University, Faculty of Engineering, Mechanical Systems Engineering, Professor, 工学部, 教授 (50094272)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | ultra high-strength steel / TRIP-aided steel / retained austenite / ausforming / forging / fatigue strength / hydrogen embrittlement / bainitic ferrite / TRIP / 組織 / 靭性 / 降伏応力 |
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| Research Abstract |
In order to develop ultra high-strength TRIP-aided forging steels with bainitic ferrite matrix (TBF steels), the effects of a new hot forging-heat-treatment process on (1) impact toughness, (2) fatigue strength and (3) hydrogen embrittlement performance of the steels were investigated. The main results are summarized as follows.
(1) High toughness of a base steel (0.2%C-1.5%Si-1.5%Mn) was achieved when hot forging at 800-900℃ and subsequent austempering at 400℃ were conducted with small size specimens. Complex additions of 0.5%Al and 0.05%Nb considerably enhanced the strength-toughness balance, which was higher than that of conventional SCM440 steel quenched and tempered. This was associated with TRIP effect of retained austenite carbon-enriched by Al and uniform microstructure refined by Nb.
(2) The TBF base steels exhibited the highest fatigue strength when austempered at 400℃ after annealing. Also, the steel were characterized by higher notched fatigue strength and lower notch sensitivity than the conventional martensitic steel. Complex addition of Al, Nb and Mo resulted in further good fatigue performance.
(3) The TBF steels possessed higher delayed fracture strength than martensitic steel. Addition of 0.5%Al improved further the hydrogen embrittlement performance of the TBF steels, differing from addition of Mn. Al stabilized the retained austenite and consequently trapped most of hydrogen. On the other hand, Nb contributed to size down prior austenite grain.
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Report
(3 results)
Research Products
(46 results)
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[Patent(Industrial Property Rights)] 耐衝撃特性と強度-延性バランスに優れた鋼製高強度加工品およびその製造方法,並びに高強度かつ耐衝撃特性に優れたディーゼルエンジン用燃料噴射管およびコモンレールの製造方法2006
Inventor(s)
増田智一, 斉藤賢司, 池田周之(以上,神戸製鋼), 杉本公一, 伊藤満大(以上,信州大学), 荒井五郎(以上,野村ユニソン(株),斉藤輝久, 坂本保司(以上,臼井国際産業(株))
Industrial Property Rights Holder
神戸製鋼, 信州大学, 野村ユニソン, 臼井国際産業
Industrial Property Number
2006-053864
Filing Date
2006-02-28
Description
「研究成果報告書概要(和文)」より
Related Report
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