自然时效态2198铝锂合金板材各向异性晶体塑性有限元模拟

Crystal plastic finite element simulation of anisotropy innatural aged 2198 Al-Li alloy sheet

基于电子背散射衍射(EBSD)数据建立了自然时效态2198铝锂合金板材的晶体塑性有限元模型,并利用控制变量法研究了5个塑性基本参数(初始硬化模量、应变率敏感系数、参考应变率、初始临界分剪切应力和饱和流动应力)对塑性变形行为的影响,通过引入代价函数,并对各个塑性参数进行优化,最终得到了能够描述自然时效态2198铝锂合金板材各向异性的塑性参数,所预测的沿RD和TD方向的应力-应变曲线与试验结果符合较好。通过晶体塑性有限元法,预测了自然时效态2198铝锂合金板材单向拉伸过程中晶体取向演变与12个滑移系对塑性变形的贡献。发现(111)[10-1]滑移系对自然时效态2198铝锂合金板材单向拉伸的塑性变形贡献最大。沿RD方向拉伸时,自然时效态2198铝锂合金板材出现强烈的[011]//TD织构。

The crystal plastic finite element model of natural aged 2198 Al-Li alloy sheet was established based on electron back scattering diffraction(EBSD)data,and the effects of five basic plastic parameters(initial hardening modulus,strain rate sensitivity coefficient,reference strain rate,initial critical shear stress,saturated flow stress)on the plastic deformation behavior were studied by using the control variable method.By introducing the cost function and optimizing each plastic parameter,the plastic parameters which can describe the anisotropy of the natural aged 2198 Al-Li alloy sheet were obtained.The predicted stress-strain curves along RD and TD directions are in good agreement with the test results.The crystal orientation evolution and the contribution of 12 slip systems to the plastic deformation of natural aged 2198 Al-Li alloy sheet during unidirectional tensile process were predicted by means of crystal plastic finite element method.It is found that(111)[10-1]slip system contributes the most to the unidirectional tensile plastic deformation of the natural aged 2198 Al-Li alloy sheet.The natural aged 2198 Al-Li alloy sheet has a strong[011]//TD texture when stretched along RD.