Multiscale Crystal Plasticity Analysis for Production of Ultrafine-Grained Metals Based on Self-Organization of Subgrain

基于亚晶自组织的超细晶金属生产的多尺度晶体塑性分析

• 批准号: 16560078
• 负责人: SHIZAWA Kazuyuki
• 金额: $ 2.37万
• 依托单位: Keio University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560078/
• 关键词: Dislocation cell structure; Subgrain; Self-organization; Polycrystal; Ultrafine-grained metal; Multiscale modeling; Reaction-diffusion equations; Crystal plasticity analysis; セル再分割

Ultrafine-grained metals (UFGM) have attracted interest as high-strength materials. It is expected in the field of material textures control that a microscopic mechanism of production process for the UFGM is numerically predicted. However, such a study has never been reported. In this study, aiming at a prediction of production process of UFGM, reaction-diffusion equations are rigorously derived, that describe the self-organization of dislocation cell structure and subgrain. A stress effect model for rate coefficients of the reaction-diffusion equations is proposed so as to reflect the information of resolved shear stress of a crystal on dislocation patterning. In order to extend this self-organization model to a model for polycrystal, a dislocation reaction term is improved so that it can express an accumulation of geometrically necessary (GN) dislocation on grain boundary and a decrease of dislocation annihilation ratio near the boundary. A difference of stage transition timing for t … More hree-stage hardening of a crystal due to difference between the initial orientations of grain is introduced into the stress effect coefficient model and a dislocation mean free path model. Furthermore, substituting the immobile dislocation density calculated from the reaction-diffusion equations into a hardening modulus of a crystal, a multiscale crystal plasticity model is developed, that couples the dislocation patterning and polycrystal deformation.A multiscale crystal plasticity simulation using a FDM for dislocation patterning and a FEM for crystal deformation is carried out applying this model to a compression problem of an FCC polycrystal plate under severe strain condition. It is numerically predicted that the cell structure in the micrometer size is formed in a grain and the GN dislocations are accumulated around grain boundary in stage II. It is also reproduced that a lot of micro shear bands generate and subgrain walls with accumulated GN dislocations are formed along the shear bands in stage III. The timing of transition from cell to subgrain is different depending on the resolved shear stress condition of each grain. Moreover, the generation process of ultrafine grain is appropriately visualized and it is clarified that GN boundaries are induced in a grain by applying severe strain locally over 2 and a grain is separated along the GN boundaries into plural fine grains in the sub-micron order with large angle boundary. This study lays a foundation of multiscale simulation that enables computationally to predict the production process of UFGM on the basis of dislocation behaviors. Less

超细晶粒金属（UFGM）作为高强度材料引起了人们的兴趣。在材料织构控制领域，人们期望对 UFGM 生产过程的微观机制进行数值预测。然而，这样的研究从未被报道过。本研究针对UFGM生产过程的预测，严格推导了描述位错胞结构和亚晶自组织的反应扩散方程。提出了反应扩散方程速率系数的应力效应模型，以反映晶体剪切应力对位错图案的影响信息。为了将该自组织模型扩展到多晶模型，改进了位错反应项，使其能够表达晶界上几何必要（GN）位错的积累以及晶界附近位错湮没率的降低。将由于晶粒初始取向差异导致的晶体三阶段硬化的阶段转变时间差异引入应力影响系数模型和位错平均自由程模型中。此外，将反应扩散方程计算出的不动位错密度代入晶体的硬化模量，建立了多尺度晶体塑性模型，将位错图案化和多晶变形耦合起来。使用FDM进行位错图案化和FEM进行晶体变形的多尺度晶体塑性模拟，将该模型应用于FCC的压缩问题 严重应变条件下的多晶板。通过数值预测，在第二阶段，晶粒中形成了微米尺寸的晶胞结构，并且GN位错在晶界周围积累。还再现了在第三阶段中产生了大量的微剪切带，并且沿着剪切带形成了具有积累的GN位错的亚晶壁。从细胞到亚晶粒的转变时间是不同的，具体取决于每个晶粒的解析剪切应力条件。此外，超细晶粒的生成过程被适当地可视化，并且清楚地表明，通过在局部施加大于2的剧烈应变，在晶粒中诱发GN晶界，并且晶粒沿着GN晶界分离成具有大角度晶界的亚微米级的多个细晶粒。这项研究为多尺度模拟奠定了基础，能够根据位错行为通过计算来预测 UFGM 的生产过程。较少的

项目成果

超微細サブグレインの自己組織化に関する転位-結晶塑性シミュレーション

超细亚晶自组织的位错晶体塑性模拟

• 发表时间: 2004
• 期刊: 日本材料学会第53期学術講演会講演論文集
• 作者: Iwamoto;M.;Tanaka;E.;Miki;K.;岩本正実;伝田耕平;岩本正実;永原斉;Shingo Oishi;Naoshi Yamaki;青柳 吉輝;青柳 吉輝;Shingo Oishi;Naoshi Yamaki;Yoshiteru Aoyagi;Yoshiteru Aoyagi;Naoshi Yamaki;Naoshi Yamaki;青柳 吉輝;Shingo Oishi;Naoshi Yamaki;海宝 寿実雄;堀部 尚裕;Naoshi Yamaki;Kazuyuki Shizawa;山本 直;Yoshiteru Aoyagi;志澤 一之
• 通讯作者: 志澤 一之

Modeling and Simulation of Crystal Plasticity Based on GN Crystal Defects for Ultrafine0Grained Metals Induced by Severe Plastic Deformation

基于强塑性变形引起的超细晶金属 GN 晶体缺陷的晶体塑性建模与仿真

• 发表时间: 2006
• 期刊: Namomaterials by Severe Plastic Deformation, Materials Science Forum 503-504
• 作者: Iwamoto;M.;Tanaka;E.;Miki;K.;岩本正実;伝田耕平;岩本正実;永原斉;Shingo Oishi
• 通讯作者: Shingo Oishi

Modeling and Simulation of Crystal Plasticity Based on GN Crystal Defects for Ultrafine-Grained Metals Induced by Severe Plastic Deformation

基于强塑性变形引起的超细晶金属 GN 晶体缺陷的晶体塑性建模与仿真

• 发表时间: 2006
• 期刊: Nanomaterials by Severe Plastic Deformation, Materials Science Forum Vol.503-504
• 作者: Iwamoto;M.;Tanaka;E.;Miki;K.;岩本正実;伝田耕平;岩本正実;永原斉;Shingo Oishi;Naoshi Yamaki;青柳 吉輝;青柳 吉輝;Shingo Oishi
• 通讯作者: Shingo Oishi

Dislocation-Crystal Plasticity Simulation Based on Self Organization for Repartition of Dislocation Cell Structures and Subgrains

基于自组织的位错晶体塑性模拟用于位错单元结构和亚晶的重新分配

• 发表时间: 2006
• 期刊: Nanomaterials by Severe Plastic Deformation, Materials Science Forum Vol.503-504
• 作者: Iwamoto;M.;Tanaka;E.;Miki;K.;岩本正実;伝田耕平;岩本正実;永原斉;Shingo Oishi;Naoshi Yamaki;青柳 吉輝;青柳 吉輝;Shingo Oishi;Naoshi Yamaki
• 通讯作者: Naoshi Yamaki

強ひずみ付与による結晶粒微細化に関するGN転位-結晶塑性シミュレーション

强应变晶粒细化的 GN 位错-晶体塑性模拟

• 发表时间: 2005
• 期刊: 日本材料学会第54期学術講演会講演論文集
• 作者: Iwamoto;M.;Tanaka;E.;Miki;K.;岩本正実;伝田耕平;岩本正実;永原斉;Shingo Oishi;Naoshi Yamaki;青柳 吉輝;青柳 吉輝;Shingo Oishi;Naoshi Yamaki;Yoshiteru Aoyagi;Yoshiteru Aoyagi;Naoshi Yamaki;Naoshi Yamaki;青柳 吉輝
• 通讯作者: 青柳 吉輝