Dislocation Density-Based Grain Refinement Modeling of Orthogonal Cutting of Titanium
Dislocation Density-Based Grain Refinement Modeling of Orthogonal Cutting of Titanium
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DOI：
10.1115/1.4027207
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发表时间：
2014-08-01
影响因子：
4
通讯作者：
Shin, Yung C.
中科院分区：
文献类型：
--
作者：
Ding, Hongtao;Shin, Yung C.
近年来，正交切削技术已被广泛应用于各种金属材料，如铝合金、铜、不锈钢、钛和镍基超级合金等的超细晶（UFG）和纳米晶显微组织的制备。然而，目前还没有预测、分析或数值工作来定量预测平面应变正交切削过程中晶粒尺寸的变化。本文采用基于位错密度的材料塑性模型，采用基于有限元的数值框架来模拟正交切削过程中的晶粒细化机理。建立了嵌入位错密度子程序的耦合欧拉-拉格朗日（CEL）有限元模型，以模拟稳态切削过程中的剧烈塑性变形和晶粒细化。对某工业纯钛（CP Ti）材料的正交切削试验进行了模拟，并与实验结果进行了比较，以评价数值解的有效性。校正了基于位错密度的材料塑性模型，以再现CP Ti在切削过程中不同应变、应变速率和温度下观察到的材料本构力学行为。结果表明，所建立的模型捕捉了材料力学行为的基本特征，并预测了CP Ti切屑在10 mm/s切削速度下的晶粒尺寸为100-160 nm。
Recently, orthogonal cutting has been exploited as a means for producing ultrafine grained (UFG) and nanocrystalline microstructures for various metal materials, such as aluminum alloys, copper, stainless steel, titanium and nickel-based super alloys, etc. However, no predictive, analytical or numerical work has ever been presented to quantitatively predict the change of grain sizes during plane-strain orthogonal cutting. In this paper, a dislocation density-based material plasticity model is adapted for modeling the grain size refinement mechanism during orthogonal cutting by means of a finite element based numerical framework. A coupled Eulerian-Lagrangian (CEL) finite element model embedded with the dislocation density subroutine is developed to model the severe plastic deformation and grain refinement during a steady-state cutting process. The orthogonal cutting tests of a commercially pure titanium (CP Ti) material are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material plasticity model is calibrated to reproduce the observed material constitutive mechanical behavior of CP Ti under various strains, strain rates, and temperatures in the cutting process. It is shown that the developed model captures the essential features of the material mechanical behavior and predicts a grain size of 100-160 nm in the chips of CP Ti at a cutting speed of 10 mm/s.