High strain rate compression behavior of a heavily stabilized beta titanium alloy: Kink deformation and adiabatic shearing
High strain rate compression behavior of a heavily stabilized beta titanium alloy: Kink deformation and adiabatic shearing
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DOI：
10.1016/j.jallcom.2017.02.284
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发表时间：
2017-06
影响因子：
6.2
通讯作者：
Youping Zheng;W. Zeng;Yubo Wang;D. Zhou;Xiongxiong Gao
中科院分区：
文献类型：
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作者：
Youping Zheng;W. Zeng;Yubo Wang;D. Zhou;Xiongxiong Gao
在分离式Hopkinson压杆系统上对Ti-35 V-15 Cr-0.3Si-0.1C β钛合金在20 °C ~ 800 °C温度范围内进行了5 × 103 s-1的高应变率压缩变形。结果表明，在高应变速率下，动态应力-应变曲线包含硬化和软化两个阶段。不同阶段的变形机制不同。在硬化阶段，扭结变形是不常见的观察。弯折带的形成被认为是负责的硬化效果。绝热剪切开始于软化阶段的应力下降。变形局限在狭窄的区域内，最终形成绝热剪切带。ASB发生了动态再结晶。在400 °C、600 °C和800 °C下形成的ASB中分别观察到了晶粒尺寸为0.28 μm、0.35 μm和4.5 μm的超细再结晶晶粒。迄今为止，测量ASB中的真实剪切应变和真实温度是非常困难的。为了准确估算ASB中的真实剪应变，本文提出了一种基于剪应变定义的ASB真实剪应变估算方法。在此基础上，提出了一种基于真实剪切应变而非经验因子的修正公式，用于预测ASB内的真实温度。在此基础上，通过旋转动态再结晶（RDR）机制，从动力学角度对目前ASB的动态再结晶进行了较好的解释。
High strain rate compression deformations at 5 × 103s−1of Ti-35V-15Cr-0.3Si-0.1C beta titanium alloy were conducted at variant temperatures from 20 °C to 800 °C on split-Hopkinson pressure bar system. It is found that the dynamic stress-strain curves at such a high strain rate contain hardening stages and softening stages. Different stages suggest different deformation mechanisms. In the hardening stages, kink deformation is uncommonly observed. The formation of kink bands is found to be responsible for the hardening effect. Adiabatic shearing began with the stress drops in the softening stages. From then on, the deformations localized in narrow regions, where adiabatic shearing bands (ASBs) formed at last. Dynamic recrystallization (DRX) occurred in the ASBs. The ultra-fine recrystallization grains with grain size of 0.28 μm, 0.35 μm, and 4.5 μm are observed in the ASBs formed at 400 °C, 600 °C and 800 °C respectively. It is really hard so far to measure the true shear strains and the true temperatures in the ASBs. In order to estimate the true shear strains in the ASBs, an original method basing on the definition of shear strain is proposed in this paper. Then a modified equation using the true shear strain rather than the empirical factor is employed to estimate the true temperatures in the ASBs. On such a base, the DRX in present ASBs is well explained in kinetics via the rotational dynamic recrystallization (RDR) mechanism.