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Property Evaluation and Application of Ultrafine Grained Steel

超细晶粒钢的性能评价及应用

基本信息

批准号：
15206077
负责人：
TAKAKI Setsuo
金额：
$ 32.53万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

For the purpose of evaluating the properties of submicron fine grained steels and exploring their possibilities of application, this study had been carried out for three years. We had 8 themes for investigating the submicron fine grained steels, but they are classified into three categories : (1)Fabrication and processing technique of submicron fine grained steels, (2)Microstructure analysis, (3)Evaluation of mechanical properties, and (4)Analysis of strengthening mechanism.We succeeded to fabricate submicron fine grained steels by adopting powder metallurgy technique (mechanical milling process). In addition, hot excursion method to form rod steel of several cm in diameter was also developed for applying to automobile parts. As for the analysis of the microstructure obtained, the local structure analysis and measurement of the dislocation density were performed by X ray diffractometry for fine selected areas ; the submicron grained structure and the dislocation substructure were caref … More ully observed with TEM ; the orientation distribution and the texture were examined with FE-SEM-EBSP method. The mechanical properties were investigated by means of tensile testing at various temperatures ranging from low temperature of liquid nitrogen to elevated temperature. As a result, it was clarified that the submicron fine grained steels do not cause brittle fracture but ductile fracture even at low temperature, and that they exhibit superplasticity at elevated temperature, leading to the excellent deformability. Besides, we insisted that the combination of the grain refinement strengthening and other strengthening mechanism should be important to realize further strengthening. On the basis of this idea, the effect of combination of grain refinement and nano-Cu precipitation was investigated, and then we found that the yield strength of the steel is sometimes explained by the addition of both strengthening mechanism. However, it was also found the new facts that the ultrafine grained steel never exhibits age hardening and dislocation strengthening; thus we feel that the submicron fine grained steels should be moved to nano-grained material in the next stage. Less

为了评价亚微米级细晶粒钢的性能并探索其应用的可能性，本研究进行了三年。亚微米级细晶粒钢的研究有8个方面，主要包括：（1）亚微米级细晶粒钢的制备与加工技术;（2）亚微米级细晶粒钢的显微组织分析;（3）亚微米级细晶粒钢的力学性能评价;此外，还开发了适用于汽车零部件的直径为几厘米的棒材热偏移成形方法。在显微组织分析方面，采用X射线衍射法对细晶区进行了局域结构分析和位错密度测量，对亚微米晶组织和位错亚结构进行了细致的观察和分析。 ...更多信息用TEM观察了薄膜的形貌，用FE-SEM-EBSP方法研究了薄膜的取向分布和织构。通过拉伸试验研究了从液氮低温到高温的不同温度下的力学性能。结果表明，亚微米级细晶粒钢即使在低温下也不会发生脆性断裂，而是发生韧性断裂，而且在高温下表现出超塑性，具有优异的变形性能。此外，我们认为，细化强化和其他强化机制相结合是实现进一步强化的重要途径。在此基础上，研究了晶粒细化和纳米Cu沉淀相结合的强化效果，发现钢的屈服强度有时可以用两种强化机制的叠加来解释。然而，也发现了新的事实，超细晶粒钢从来没有表现出时效硬化和位错强化，因此，我们认为，亚微米细晶粒钢应该在下一阶段向纳米晶粒材料。少

项目成果

期刊论文数量（52）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Effect of Grain Size on Microstructure Development During Deformation in Polycrystalline Iron

晶粒尺寸对多晶铁变形过程中微观结构发展的影响

DOI：
发表时间：
2004
期刊：
Proc.2nd International Conference on Nanomaterials by Severe Plastic Deformation
影响因子：
0
作者：
K.Kawasaki;H.Hidaka;T.Tsuchiyama;S.Takaki
通讯作者：
S.Takaki

「研究成果報告書概要(欧文)」より

摘自《研究结果报告摘要（欧洲）》