Control of degradation of materials properties in recycling by grain boundary engineering

通过晶界工程控制回收过程中材料性能的退化

• 批准号: 15201015
• 负责人: TSUREKAWA Sadahiro
• 金额: $ 22.21万
• 依托单位: Tohoku 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
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15201015/
• 关键词: recycling; grain boundary engineering; magnetic field; steel; grain boundary segregation; 磁気特性; 粒界性格分布; 急冷凝固法; 双晶; ステンレス鋼; 鉄鉱; 粒界偏析脆化; 粒界エネルギー; 破壊靭性

Today, recycled materials are universally growing in importance because of savings of material resources, energy. However, harmful impurities like Sn and Cu are inevitably contained in scrap steel, and segregate to grain boundaries due to their low solid solubility in iron. Their segregation severely degrades mechanical properties of recycled steel. The motivation of this project was to develop methodology for controlling materials degradation on the basis of grain boundary engineering. The chief results obtained are follows.1. Controlling grain boundary segregation and segregation embrittlement by application of magnetic field : It was found that magnetic annealing of Fe-Sn alloy at 973K in ferromagnetic temperature region could suppress Sn segregation to grain boundaries, resulting in a significant increase of fracture toughness. The higher magnetic field strength, the more increases fracture toughness of Fe-Sn alloys.2. Magnetic property of magnetically annealed Fe-Sn alloy : VSM measurements revealed that coercive force for magnetically annealed Fe-0.8at%Sn alloy decreased with increasing magnetic field strength : i.e., softness of this alloy can be enhanced by magnetic annealing.3. Introduction of insensitive microstructure to grain boundary segregation : We studied materials processing to introduce insensitive microstructure to grain boundary segregation, and found that a rapid solidification was useful to increase a fraction of special boundaries. The fraction of special boundaries was approximately 45% in a rapidly solidified sample, whereas it was 20% in a thermo-mechanically treated one. Three-point bend tests of these samples revealed that the former could show a good plasticity but the latter fractured without showing any plastic deformation.

如今，由于节省了材料资源和能源，回收材料的重要性普遍增加。然而，废钢中不可避免地含有Sn和Cu等有害杂质，并且由于它们在铁中的固溶度低而偏析到晶界。它们的偏析严重降低了再生钢的机械性能。该项目的动机是开发基于晶界工程的材料降解控制方法。主要研究结果如下： 1．通过施加磁场控制晶界偏析和偏析脆化：研究发现，铁磁温度区的Fe-Sn合金在973K下进行磁性退火可以抑制Sn向晶界的偏析，从而显着提高断裂韧性。磁场强度越高，Fe-Sn合金的断裂韧性增加越多。2．磁退火Fe-Sn合金的磁性能：VSM测量表明，磁退火Fe-0.8at%Sn合金的矫顽力随着磁场强度的增加而降低：即磁退火可以增强该合金的柔软度。 3．引入对晶界偏析不敏感的微观结构：我们研究了材料加工以引入对晶界偏析不敏感的微观结构，并发现快速凝固有助于增加特殊晶界的比例。在快速凝固的样品中，特殊边界的比例约为 45%，而在热机械处理的样品中，特殊边界的比例为 20%。这些样品的三点弯曲试验表明，前者表现出良好的塑性，但后者在没有出现任何塑性变形的情况下断裂。

项目成果

Diffusion of carbon and titanium in γ-iron in a magnetic field and a magnetic field gradient

• DOI: 10.1007/s10853-005-2683-3
• 发表时间: 2005-06-01
• 期刊: JOURNAL OF MATERIALS SCIENCE
• 影响因子: 4.5
• 作者: Nakamichi, S;Tsurekawa, S;Chiba, A
• 通讯作者: Chiba, A

A mechanism of plane matching boundary-assisted α/γ phase transformation in Fe-Cr alloy based on in-situ observation

基于原位观察的Fe-Cr合金平面匹配边界辅助α/γ相变机制

• 发表时间: 2005
• 期刊: Zeitschrift fur Metallkunde 96
• 作者: Saito K;Kim HS;Sakai N;Ishizuka M;Kazusaka A;Fujita;S.;T.Watanabe
• 通讯作者: T.Watanabe

Prospect of Grain Boundary Study in Ferromagnetic Materials

铁磁材料晶界研究的展望

• 发表时间: 2004
• 期刊: Materia Japan 43・2
• 作者: T.Watanabe;H.Fujii;SHIGEAKI KOBAYASHI;S.Tsurekawa;Sadahiro Tsurekawa;T.Watanabe;H.Fujii;SHIGEAKI KOBAYASHI;S.Tsurekawa;Sadahiro Tsurekawa;H.Takahashi;S.Tsurekawa;R.Ishibashi;S.Tsurekawa;S.Nakamichi;S.Tsurekawa;T.Watanabe;Shigeaki Kobayashi;T.Watanabe;T.Watanabe;T.Watanabe;R.Ishibashi;S.Tsurekawa;S.Nakamichi;S.Tsurekawa;T.Watanabe;Shigeaki Kobayashi;T.Watanabe;T.Watanabe;T.Watanabe;S.Tsurekawa;T.Watanabe;S.Nakamichi;S.Tsurekawa;川原 浩一;Sadahiro Tsurekawa;T.Watanabe;T.Watanabe;K.Kawahara
• 通讯作者: K.Kawahara

Effect of grain boundary character distribution on stress corrosion cracking behavior in austenitic stainless steels

• DOI: 10.4028/www.scientific.net/msf.475-479.3863
• 发表时间: 2005-01-01
• 期刊: PRICM 5: THE FIFTH PACIFIC RIM INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS AND PROCESSING, PTS 1-5
• 作者: Ishibashi, R;Horiuchi, T;Shoji, T
• 通讯作者: Shoji, T

In-situ Observation on Interphase Boundary Migration and Grain Growth during α/γ Phase Transformation in Iron Alloys

铁合金α/γ相变过程中相间边界迁移和晶粒长大的原位观察

• 发表时间: 2004
• 期刊: Materials Science Forum 467-470
• 作者: 小澤晃史;伊藤克亘;武田一哉;脇田敏裕;板倉文忠;T.Watanabe
• 通讯作者: T.Watanabe