Work-hardening behavior of polycrystalline aluminum alloy under multiaxial stress paths
Work-hardening behavior of polycrystalline aluminum alloy under multiaxial stress paths
复制标题
DOI：
10.1016/j.ijplas.2013.07.003
复制
发表时间：
2014-02
影响因子：
9.8
通讯作者：
Kengo Yoshida;Asato Ishii;Y. Tadano
中科院分区：
文献类型：
--
作者：
Kengo Yoshida;Asato Ishii;Y. Tadano
采用轴向载荷-内压-扭转型试验机对A3003-O薄壁管状试样进行单轴、双轴和三轴应力路径试验。对于线性多轴应力路径，保持轴向应力、周向应力和剪应力的比值恒定，测量各应力路径下的应力-应变关系。根据单位体积的塑性功对试样的加工硬化行为进行了评价，并构造了等量塑性功的轮廓。轮廓形状随塑性应变的增大而逐渐变化。因此，试样的加工硬化量取决于塑性工作和施加的应力路径。为了弄清这种加工硬化行为的来源，采用晶体塑性模型进行了数值模拟。采用两种硬化模型。在一个模型中，滑移阻力作为累积滑移的函数给出，而在另一个模型中，滑移阻力作为位错密度的函数给出。累积滑移模型的宏观流变应力演化只依赖于塑性功，不能预测试验趋势。另一方面，基于位错密度的模型再现了实验中观察到的与应力路径相关的加工硬化行为，尽管没有完全达到定量一致。在模拟中，位错密度的演化速率随应力路径的变化而变化，这被认为是应力路径相关加工硬化行为的来源。
A thin-walled tubular specimen of A3003-O is subjected to uniaxial, biaxial, and triaxial stress paths using an axial load-internal pressure-torsion type test machine. For linear multiaxial stress paths, the ratios of axial, circumferential, and shear stresses are kept constant, and the stress–strain relations for various stress paths are measured. The work-hardening behavior of the specimen is evaluated based on the plastic work per unit volume, and contours of equal plastic work are constructed. The shape of the contour changes progressively with increasing plastic strain. Therefore, the amount of work hardening of the specimen depends on the plastic work and the applied stress path. In order to clarify the source of such work-hardening behavior, numerical simulations are performed using the crystal plasticity model. Two hardening models are adopted. In one model, the slip resistance is given as a function of accumulated slip, and, in the other model, the slip resistance is given as a function of dislocation density. The evolution of macroscopic flow stress depends only on the plastic work for the accumulated-slip-based model, and this model cannot predict the experimental trend. On the other hand, the dislocation-density-based model reproduces the stress-path dependent work-hardening behavior observed in the experiments, although quantitative agreement is not fully achieved. In the simulation, the evolution rate of the dislocation density varies depending on the stress path, which is identified as the source of the stress-path-dependent work-hardening behavior.