作者：张军1, 汪洋2
作者单位：1. 中国工程物理研究院总体工程研究所, 四川 绵阳 621999;
2. 中国科学技术大学近代力学系, 安徽 合肥 230027
关键词：钛合金;应变率;绝热温升;历史效应
摘要：
为精确评价钛合金热率相关的力学行为，利用冲击拉伸试验系统和基于单应力脉冲加载的冲击拉伸复元试验技术分别获得TC11钛合金在高应变率（102~103 s-1）范围内的绝热应力-应变曲线和等温应力-应变曲线，实现拉伸响应的热力解耦；利用冲击拉伸加卸载试验技术实施变温度和变应变率测试，研究历史效应对于本构行为的影响。结果表明：TC11的初始屈服行为呈现温度软化和应变率强化特性，而等温塑性应变硬化行为表现出温度和应变率不敏感特征，瞬态绝热温升是导致材料动态应变硬化率降低的主要原因；高应变率加载时材料内的热功转换系数约为0.9，且其拉伸力学行为无明显的温度和应变率历史效应。实验结果为建立钛合金的本构模型奠定试验基础。
A single pulse loading method of split-Hopkinson tension bar and its application in the tension behavior of titanium alloy
ZHANG Jun1, WANG Yang2
1. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 621999, China;
2. Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China
Abstract: In order to understand and evaluate the thermal-mechanically dependent behavior of titanium alloy,the uniaxial tension tests and recovery tests are performed to obtain the adiabatic and isothermal stress-strain curves at strain rates ranging from 102 s-1 to 103 s-1 respectively on a single pulse loading SHTB.The variable temperature and strain rate tests are conducted to study the history effect on the constitutive model.Experimental results indicate that there is a positive strain-rate sensitivity and a thermal-softening effect with respect to the initial yield behavior.Meanwhile,the strain hardening behavior shows insensitive on the strain rates and/or temperatures.The adiabatic temperature rise is the main reason that strain hardening rate of titanium alloy decreases to instability.The temperature and strain rate jump tests indicate that the value of temperature rise conversion coefficient is 0.9,approximately.The tensile mechanical behavior has no apparent history effects on strain rate and temperature.The corresponding progress may lay the experimental foundation for the constitutive model of titanium alloy.
Keywords: titanium alloy;strain rate;adiabatic temperature rise;history effect
2016, 42(10): 123-127,137 收稿日期: 2016-4-25;收到修改稿日期: 2016-6-3
基金项目: 国家自然科学基金项目（11172288）
作者简介: 张 军(1988-),男,重庆市人,助理研究员,博士,主要从事钛合金动态力学行为研究。
参考文献
[1] ZHANG J, WANG Y. Tension behavior of Ti-6.6Al-3.3Mo-1.8Zr-0.29Si alloy over a wide range of strain rates[J]. Materials Letters,2014(124):113-116.
[2] 赵永庆. 国内外钛合金研究的发展现状及趋势[J]. 中国材料进展,2010,29(5):1-8.
[3] ANAND L, KIM K H, SHAWKI T G. Onset of shear localization in viscoplastic solids[J]. Journal of the Mechanics and Physics of Solids,1987,35(4):407-427.
[4] 徐永波,白以龙. 动态载荷下剪切变形局部化、微结构演化与剪切断裂研究进展[J]. 力学进展,2007,37(4):496-520.
[5] TANNER A B, MCGINTY R D, MCDOWELL D L. Modeling temperature and strain rate history effects in OFHC Cu[J]. International Journal of Plasticity,1999,15(6):575-603.
[6] NEMAT-NASSER S, ISACS J B, STARRETT J E. Hopkinson techniques for dynamic recovery experiments[J]. Proceedings of the Royal Society of London Series a-Mathematical Physical and Engineering Sciences,1991, 435(1894):371-391.
[7] NEMAT-NASSER S, ISAACS J B. Direct measurement of isothermal flow stress of metals at elevated temperatures and high strain rates with application to Ta and TaW alloys[J]. Acta Materialia,1997,45(3):907-919.
[8] NEMAT-NASSER S, LI Y L. Flow stress of FCC polycrystals with application to OFHC Cu[J]. Acta Materialia,1998,46(2):565-577.
[9] NEMAT-NASSER S, GUO W G, NESTERENKO V F, et al. Dynamic response of conventional and hot isostatically pressed Ti-6Al-4V alloys:experiments and modeling[J]. Mechanics of Materials,2001,33(8):425-439.
[10] 汪洋. 基于Hopkinson杆的材料动力学试验技术[C]//中国科协第235次青年科学家论坛——极端复杂测试环境下实验力学的挑战与应对,2011.
[11] MACDOUGALL D A S, HARDING J. A constitutive relation and failure criterion for Ti6Al4V alloy at impact rates of strain[J]. Journal of the Mechanics and Physics of Solids,1999,47(5):1157-1185.
