摘要
采用等径通道挤压(ECAP)法制备了超细晶铜,分析其微结构的热稳定性及其对材料动态力学性能的影响。利用Hopkinson压杆及MTS液压伺服实验机对ECAP超细晶铜和原始铜帽型剪切试样进行应变控制加载,结合图像数字相关法及"冻结"回收试样的微观和X射线衍射分析,对其动态剪切变形行为及微观组织演化开展研究。结果表明:ECAP后的超细晶铜在准静态剪切下具有应变硬化特征,但在高应变率下剪切应力-剪切应变曲线呈软化特征;高加载率下产生动态再结晶的绝热剪切带是导致应变硬化率为负的原因;按塑性功计算的超细晶铜再结晶温度仅为325 K,因此超细晶铜在高应变率下易发生绝热剪切失稳变形现象。
The thermal stability of ultra-fine-grained（ UFG） copper microstructure prepared by equal channel angular pressing（ ECAP） method and its influence on the mechanical properties of the material are studied. The Hopkinson pressure bar and MTS hydraulic servo testing machine are used to test ECAP ultrafine grained copper and annealed pure copper samples under strain controlled loading. The evolutions of its dynamic shear deformation behavior and microstructure are studied by digital image correlation method and the microscopic and XRD analysis of ＂frozen＂recovered samples. The test shows that the ECAP UFG copper has strain hardening characteristics under quasi-static shear loading; the shear stressstrain curve presents strain softening characteristics at high strain rate; and the adiabatic shear dynamic recrystallization zone results in strain hardening rate being negative at high loading rate. The recrystalliza-tion temperature of ultrafine grained copper calculated by plastic work is only 325 K. Therefore,the adiabatic shear instability of ultrafine grained copper at high strain rate is easy to occur.
作者
宋鹏飞
董新龙
付应乾
索涛
SONG Peng-fei1 , DONG Xin-long1 , FU Ying-qian1,2 , SUO Tao3(1. Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, Zhejiang, China; 2. Sehool of Meehatronieal Engineering, Beijing Institute of Teehnology, Beijing 100081, China; 3. School of Aeronautics, Northwestern Polyteehnieal University, Xi＇an 710072, Shaanxi, Chin)
出处
《兵工学报》
EI
CAS
CSCD
北大核心
2018年第4期763-771,共9页
Acta Armamentarii
基金
国家自然科学基金项目(U1230122
11672143)
关键词
超细晶铜
等径通道挤压法
动态剪切
应变软化
动态再结晶
绝热剪切
ultrafine grained copper
equal channel angular pressing method
dynamic shear
softening characteristic
recrystallization
adiabatic shearing
