Establishment of size-dependant constitutive model of micro-sheet metal materials  

微细薄板尺度依赖的材料本构模型的构建(英文)

作　　者：林晓娟[1,2] 王广春[1] 郑伟[2] 姜华[1] 李锦[2] 

机构地区：[1]山东大学材料液固结构演变与加工教育部重点实验室,济南250061 [2]山东建筑大学材料科学与工程学院,济南250101

出　　处：《Transactions of Nonferrous Metals Society of China》2014年第2期470-476,共7页中国有色金属学报（英文版）

基　　金：Project(50975163)supported by the National Natural Science Foundation of China;Project(IRT0931)supported by Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China

摘　　要：The inherent mechanism of size effect in micro-sheet material behavior of plastic forming was explained by the surface layer model and theory of metal crystal plasticity. A size-dependant constitutive model based on the surface layer model was established by introducing the scale parameters and modifying the classical Hall-Petch equation. The influence of the geometric dimensions and the grain size on the flow behavior of the material was discussed using the new material constitutive model. The results show that, the flow stress decreases while the sheet metal thickness decreases when the grain size keeps constant, and the micro-sheet metal with a larger grain size is more easily to be influenced by the size effects. The material constitutive model established is validated by the stress-strain curve of the micro-sheet metal with different thicknesses derived from the tensile experiments. The rationality of the material model is verified by the fact that the calculation results are consistent with the experimental results.通过表面层理论和金属晶体塑性变形原理解释微细薄板材料在塑性变形中产生尺寸效应的内在机理。引入尺度参数,对经典的Hall-Petch公式进行修正,建立基于表面层模型理论的尺度依赖材料模型。利用所建立的材料模型分析微细薄板厚度及其晶粒尺寸对材料成形流动性能的影响。在晶粒尺寸一定的情况下,随着微细薄板厚度的减小,材料流动应力逐渐降低;晶粒尺寸越大的微细薄板,其流动变形的尺寸效应现象越明显。利用不同厚度的不锈钢和纯铜箔材的微细薄板拉伸真应力-应变曲线对所建立的材料模型进行验证,计算结果与实验结果比较吻合,验证了所建立的材料模型的合理性。

关 键 词：sheet metal MICRO-FORMING constitutive model scale parameters pure copper foil 

分 类 号：TG115[金属学及工艺—物理冶金]