Plastic deformation of AA6061-T6 at elevated temperatures: experiments and modeling
Plastic deformation of AA6061-T6 at elevated temperatures: experiments and modeling
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DOI：
10.1016/j.ijmecsci.2021.106943
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发表时间：
2021-11
影响因子：
7.3
通讯作者：
B. K. Roy;Y. Korkolis;Y. Arai;W. Araki;Takafumi Iijima;Jin Kouyama
中科院分区：
文献类型：
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作者：
B. K. Roy;Y. Korkolis;Y. Arai;W. Araki;Takafumi Iijima;Jin Kouyama
采用实验-数值相结合的方法研究了AA6061-T6铝合金的温度依赖性加工硬化。在室温至500 ℃范围内进行了单轴拉伸试验，建立了直至断裂的力-位移曲线。随着温度的升高，材料的屈服强度和加工硬化率均降低。尽管伸长率显著增加，但均匀伸长率仍然有限，这表明在高温试验中早期出现了弥漫性颈缩。提出了一种识别高温和单轴拉伸均匀变形极限外加工硬化曲线的简化方法。该技术使用等温，速率相关，有限元（FE）模型的实验。后颈化硬化曲线由混合的Swift/ voice硬化规律和Johnson-Cook应变速率依赖关系表示。为了确定每个温度下的材料模型参数，构建了一个将实验和有限元预测的力-位移曲线相关联的目标函数并最小化。然后，这些模型参数在这里考虑的温度范围内与傅里叶级数拟合，提供适合于随后在成形和结构问题的有限元分析中实施的平滑函数。结果表明，利用这些材料参数建立的有限元模型能很好地再现高温实验的全场特征。
The temperature-dependent work-hardening of AA6061-T6 aluminum alloy is investigated using a combined experimental-numerical approach. Uniaxial tension experiments are performed from room temperature to 500 °C, and the force-displacement curves up to fracture are established. Both the yield strength and the work-hardening rate of the material decrease with increasing temperature. Despite the marked increase in the elongation-to-fracture, the uniform elongation remains limited, indicating the early appearance of diffuse necking in the elevated temperature tests. A simplified technique for identifying the work-hardening curves at elevated temperatures and beyond the limit of uniform deformation in uniaxial tension is proposed. The technique uses an isothermal, rate-dependent, finite element (FE) model of the experiments. The post-necking hardening curve is represented by a hybrid Swift/Voce hardening law combined with a form of Johnson-Cook strain-rate dependence. To identify the material model parameters at each temperature, an objective function that correlates the experimental and FE-predicted force-displacement curves is constructed and minimized. These model parameters are then fit with Fourier series across the temperature range considered here, providing smooth functions suitable for subsequent implementation in FE analyses of forming and structural problems. As an illustration, it is shown that a FE model utilizing these material parameters reproduces the full-field features of the elevated temperature experiments very well.