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1、硕士学位论文 纯钛塑性变形行为的晶体塑性 有限元模拟 THE FINITE ELEMENT SIMULATION ON PLASTIC BEHAVIOR OF PURE TITANIUM 黄晓华 2010 年 7 月 国内图书分类号：TG113.12 学校代码：10213 国际图书分类号: 669.017.3 密级：公开 工学硕士学位论文 纯钛塑性变形行为的晶体塑性 有限元模拟 硕 士 研 究 生： 黄晓华 导 师： 来忠红 副教授 申 请 学 位： 工学硕士 学 科、专 业： 材 料 学 所 在 单 位： 材料科学与工程学院 答 辩 日 期： 2010 年 7 月 授 予 学 位 单 位：
2、哈尔滨工业大学 Classified Index: TG113.12 U.D.C: 669.017.3 Dissertation for the Master Degree in Engineering THE FINITE ELEMENT SIMULATION ON PLASTIC BEHAVIOR OF PURE TITANIUM Candidate： Huang Xiaohua Supervisor： Associate Prof. Lai Zhonghong Academic Degree Applied for： Master of Engineering Speciality： M
3、aterials Science Affiliation： School of Materials Science and Engineering Date of Defence: July, 2010 Degree-Conferring-Institution:Harbin Institute of Technology 哈尔滨工业大学工学硕士学位论文 摘 要 本文采用晶体塑性有限元(Crystal Plasty Finite Element Method，CP- FEM)为基础，结合 Voronoi 图表技术建立了包含纯钛材料基本参数的单晶 体和多晶体塑性变形有限元模型，从细观角度研究了晶
4、体的变形行为。 首先利用晶体塑性有限元方法，建立了纯钛单晶塑性变形模型，对钛单 晶体的拉伸变形行为进行了研究，模拟结果表明在边界约束条件下，单晶体 拉伸变形的同时发生了取向的旋转，其滑移系的滑移方向会逐步趋向于与拉 伸方向平行。 利用建立的单晶体模型研究了晶体初始取向与晶体滑移的宏观力学响关 系，结果表明，软位向方向拉伸的拉伸应力小于硬位向方向拉升应力，模拟 变形过程符合 Schmid 定律。 通过 Voronoi 图表信息建立了 TA2 多晶体模型，并模拟了拉伸变形，对 照真实材料拉伸实验，分析了晶体变形过程的外形、组织形貌及应力应变关 系，模拟与实验结果接近。分段表征了 TA2 多晶体模型
5、变形的应力应变演 化过程，描述了多晶体塑性变形弹性阶段、屈服阶段、硬化阶段与颈缩阶段 应力应变分布，详细分析了晶粒变形的不均匀性的微观机制，说明了桔皮组 织的形成过程。 分析了不同晶粒尺寸对多晶体塑性变形行为的影响，研究结果表明，随 着晶粒度减小，晶体屈服强度增大，硬化曲线变陡，结果符合Hall-Petch关 系，预测TA2 纯钛的Hall-Petch常数为0=64.9MPa，K=473.3MPa?m1/2。 利用设定同取向晶粒建立织构模型的方法研究了初始织构对多晶体变形 各向异性及应力应变关系的影响，结果表明随着织构强度的升高，多晶体变 形不均匀性增大，多晶体屈服强度升高，硬化曲线变陡。 关
6、键词：TA2 纯钛；塑性变形；有限元模拟；晶粒取向；晶粒尺寸；织构 - - I哈尔滨工业大学工学硕士学位论文 Abstract Based on Crystal Plasty Finite Element Method (CP-FEM) and Voronoi diagram, the poly-crystal plasticity finite element model of single crystalline and polycrystalline materials of TA2 pure titanium is set up. And the deformation behavio
7、r of crystal from the microscopic view was researched by this finite element model. The tensile deformation behavior of single crystalline was studied firstly and the results show that the rotation of orientation occurred at the same time with the tensile deformation of single crystalline and the sl
8、ip direction of slip- systems could gradually parallelled with the tensile direction. Influence of orientation factors during uniaxial tension of single crystal metal is studied using the model of single crystalline. The results show that different orientation factors have contributed to the yield s
9、trength and tensile stress during plastic deformation. With the orientation factor reduced, the yield sress of single crystalline becomes lower, which accords with Schmids law. Compare the results of the model of single crystalline with the results of the actual material tensile tests, the change of
10、 metallographic structure and the tensile curve from simulation analysis results are well in agreement with that of experment. The relationship between the deformation course、the morphology of microstructures and the stress was analyzed, the evolution of stress and strain of polycrystalline deformat
11、ion were catalyzed, the stress and strain distributions in elastic stage、plastic stage、hardening stage and the necking stage were described. The inhomogeneity of micro mechanism of plastic deformation of polycrystalline was described in detail. According to the inhomogeneity micro mechanism, the for
12、mation mechanism of tangerine peel is investigated. The influences of the different grain size to the behavior of the plastic deformation of polycrystalline were analyzed. The yield stress increased with the decreasing of the size of crystal grains, the hardening curve began to climb quite steeply a
13、nd the maximum tensile stress increased. The increasing rule accord with Hall-Petchs law, the predictive factors of TA2 titanium by simulation are 0=64.9MPa，K=473.3MPa?m1/2. - - II哈尔滨工业大学工学硕士学位论文 The influences of the initial texture to the anisotropy of the polycrystalline deformation were research
14、ed using the method of setting the texture model of same orientation grains. The results show that with the increasing of the strength of texture, the inhomogeneity of the deformation of polycrystalline increased, the yield stress also increases, the hardening curve began to climb quite steeply and the maximum tensile stress increased. Keywords: TA2 pure titanium, plastic deoformation, plasticity finite element, crystal orientation, size of crystal grains, texture - - III哈尔滨工业大学工学硕士学位论文 目 录 摘 要 . I Abstract.II第 1 章 绪论.1 1.1 纯钛概述.
