Micro-bending of metallic crystalline foils by non-local dislocation density based crystal plasticity finite element model  

基于非局部位错密度晶体塑性有限元模型的金属晶体薄膜微弯曲变形特点(英文)

作　　者：章海明[1] 董湘怀[1] 王倩[1] 李河宗[2] 

机构地区：[1]上海交通大学模具CAD国家工程研究中心,上海200030 [2]河北工程大学机电工程学院,邯郸056038

出　　处：《Transactions of Nonferrous Metals Society of China》2013年第11期3362-3371,共10页中国有色金属学报（英文版）

基　　金：Projects(50835002,50821003,50975174,51275297)supported by the National Natural Science Foundation of China;Projects(200802480053,20100073110044)supported by the PhD Programs Foundation of Ministry of Education of China

摘　　要：A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both statistically stored dislocations （SSDs） and geometrically necessary dislocations （GNDs） are taken as the internal state variables. The strain gradient hardening in micro-bending of single-grained metal foils was predicted by evolution of GNDs. The predicted results were compared with the micro-hardness distribution of the previous micro-bending experiments of CuZn37 a-brass foils with coarse grains and fine grains. Comparison of the simulated dislocation densities distribution of SSDs and GNDs with the experimental results shows that different micro-hardness distribution patterns of the coarse and fine grain foils can be attributed to the corresponding SSDs and GNDs distributions. The present model provides a physical insight into the deformation mechanism and dislocation densities evolution of the micro-bending process.采用考虑非均匀微观结构的非局部位错密度晶体塑性有限元模型,研究金属晶体薄膜材料微弯曲塑性变形的特点。该模型采用统计存储位错密度和几何必需位错密度作为其内部状态变量,通过几何必须位错密度的演化来预测单晶体金属薄膜材料微弯曲中的应变梯度效应。采用不同晶粒大小的CuZn37α-黄铜多晶体薄膜进行微弯曲实验,并测量试样微弯曲变形后的微硬度分布图。将模拟得到的位错密度分布与实验测得的微硬度分布进行对比,发现粗晶试样和细晶试样微硬度分布的不同主要是由统计存储位错密度和几何必须位错密度引起的。基于微观物理机理,研究微弯曲变形的特点和位错密度的演化。

关 键 词：crystal plasticity micro-bending statistically stored dislocations geometrically necessary dislocations 

分 类 号：TG111[金属学及工艺—物理冶金]