Modified constitutive model and workability of 7055 aluminium alloy in hot plastic compression  

7055铝合金热压缩变形修正本构模型及热加工性（英文）

作　　者：ZHANG Tao ZHANG Shao-hang LI Lei LU Shi-hong GONG Hai 张涛;张少航;李磊;鲁世红;龚海(College of Mechanic and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;State Key Laboratory of High Performance Complex Manufacturing,Central South University,Changsha 410083,China)

机构地区：[1]College of Mechanic and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China [2]State Key Laboratory of High Performance Complex Manufacturing,Central South University,Changsha 410083,China

出　　处：《Journal of Central South University》2019年第11期2930-2942,共13页中南大学学报（英文版）

基　　金：Project(51175257)supported by National Natural Science Foundation of China;Project(BK20170785)supported by the Natural Science Foundation of Jiangsu Province,China;Project(BE2016179)supported by Science and Technology Planning Project of Jiangsu Province,China;Project(Kfkt2017-08)supported by Open Research Fund of State Key Laboratory for High Performance Complex Manufacturing,Central South University,China

摘　　要：To obtain flow behavior and workability of 7055 aluminium alloy during hot deformation,hot compression tests at different temperatures and strain rates are conducted.True stress?strain curves of 7055 aluminium alloy under different conditions are obtained and the flow stress increases with ascending strain rate and descending temperature.For Arrhenius constitutive equation,each material parameter is set as a constant,which will bring forth large error for predicting flow behavior.In this work,material parameters are fitted as a function of temperature or strain rate based on experimental results and a modified constitutive equation is established for more accurate prediction of flow behavior of 7055 aluminium alloy.The effects of temperature and strain rate on power dissipation and instability are analyzed to establish a processing map of 7055 aluminium alloy.The dominant deformation mechanism for microstructure evolution at different deformation conditions can be determined and high efficiency of power dissipation may be achieved from power dissipation map.Meanwhile,proper processing parameters to avoid flow instability can be easily acquired in instability map.According to the processing map,optimized processing parameters of 7055 aluminium alloy are temperature of 673?723 K and strain rate of 0.01?0.4 s^?1,during which its efficiency of power dissipation is over 30%.Finite element method(FEM)is used to obtain optimized parameter in hot rolling process on the basis of processing map.为了获得热变形中7055铝合金流变行为及热加工性,开展材料在不同温度和应变速率下热压缩实验.基于实验获得7055铝合金在不同变形条件下真应力-真应变曲线,流变应力随着应变速率的升高和温度的降低而增大.Arrhenius双曲正弦本构方程中每个材料参数均设置为常数,预测材料流变行为时误差较大.本文建立修正的Arrhenius本构方程,能更准确地预测材料高温流变行为,根据热压缩实验结果,修正方程中每个材料参数均拟合为温度和应变速率的函数.同时,建立了7055铝合金热加工图,分析了温度和应变速率对能量耗散及流变失稳因子的作用规律.通过热加工图,能获得不同变形条件下材料主导变形机制;通过能量耗散图,能获得高效率的能量耗散;通过流变失稳图能获得合理的工艺参数,避免热加工中的流变失稳现象.通过热加工图,可获得较优的7055铝合金热变形参数:变形温度673~723 K,应变速率0.01~0.4 s^-1,在该参数范围内能量耗散率超过30%.基于热变形图,采用有限元模型获得了该材料热轧变形较优的工艺参数.

关 键 词：7055 aluminium alloy flow behavior modified constitutive equation processing map optimized parameters 

分 类 号：TG1[金属学及工艺—金属学]