Ti_2AlNb合金高应变率下流动应力特征与本构关系  

Flow Stress Characteristics and Constitutive Relation of Ti_2AlNb Alloy Under High Strain Rate

作　　者：韩国强 谢兰生[1] 陈明和[1] 司松社 吴荣华 Han Guoqiang;Xie Lansheng;Chen Minghe;Si Songshe;Wu Ronghua(Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;AECC Xi'an Aero-engine LTD,Xi'an 710021,China)

机构地区：[1]南京航空航天大学,江苏南京210016 [2]中国航发西安航空发动机有限公司,陕西西安710021

出　　处：《稀有金属材料与工程》2019年第3期847-852,共6页Rare Metal Materials and Engineering

摘　　要：利用电子万能试验机和分离式Hopkinson压杆得到Ti_2AlNb合金准静态拉伸曲线及高应变率下动态压缩应力-应变曲线,观察分析变形后试样的微观组织,研究其高应变率下的流动应力特征。结果表明:在应变率2500～7500 s-1范围内,Ti_2AlNb合金的流动应力对应变率有较强的敏感性,且具有应变强化、应变率增强及增塑效应;应变率为5500、6500、7500s-1的3组试样中观察到了与加载方向约成45°的绝热剪切带。改进Johnson-Cook本构模型,拟合实验数据得到Ti_2AlNb合金室温下的动态塑性本构关系,与实验对比,改进后的模型能够较好地描述Ti_2AlNb合金在高应变率下的流动应力。The impact tests were carried out using the split Hopkinson pressure bar(SHPB)under a strain rate of 103~104 s^-1,and the quasi-static tensile tests were performed on an electronic universal testing machine to investigate the dynamic compression behavior of Ti2AlNb alloy.Microstructures of the specimens after compression were observed and analyzed.The results indicate that the Ti2AlNb alloy has enhanced strain rate,plasticizing effect and softening action of adiabatic temperature rise.The flow stress is sensitive to the strain rate within a strain rate range of 2500~7500 s^-1.Adiabatic shear bands with a loading direction of 45owere observed in specimens with strain rates of 5500,6500,7500 s^-1.The Johnson-Cook equation was used to evaluate the related material constants in order to predict the stress-strain curves.Compared with the experimental results,the predicted stress-strain behavior matches well with that measured experimentally in the current SHPB experiments.

关 键 词：Ti2AlNb合金 高应变率 流动应力 Johnson-Cook本构模型 

分 类 号：TG146.23[一般工业技术—材料科学与工程]