铝合金2A70高应变率力学性能及其本构关系实验研究

在室温下,利用分离式Hopkinson拉杆系统进行了平行和垂直流线方向切割的铝合金2A70圆棒试样的高应变率(1300~2300/s)拉伸实验;利用分离式Hopkinson压杆系统进行了圆柱试样的高应变率(1100~11000/s)压缩实验,分析了应变率与试样切割方向对试样力学性能的影响,并对比研究了不同应变率下试样断口的形貌。实验结果表明,铝合金2A70的屈服强度在应变率达到11000/s时会得到一定提高;垂直流线切割的试样强度略高于平行流线切割的试样;随应变率升高,拉伸试样的断口更为平滑,颗粒细密,但压缩试样会形成环状的粗晶区。最后基于实验数据拟合了J-C(Johnson-Cook)本构模型参数。

Experimental Study of Mechanical Properties at High Strain Rate and Constitutive Relation of Aluminum Alloy 2A70

High strain rate tension(1300-2300/s) and compression tests(1100-11000/s) of aluminum alloy 2A70 were conducted at room temperature by utilizing split Hopkinson tensile bar. In tensile tests, two kinds of round bar specimens, cut along parallel and perpendicular to flow line orientation, were tested respectively. In compression tests, cylindrical specimens were tested. The effect of strain rate and cut orientation on the mechanical characterisrics of specimens was analyzed. Comparative study of sample fracture morphology at different strain rates was carried out. Experimental results show that the yield strength of aluminum alloy 2A70 increases when strain rate reaches 11000/s; the specimens cut in perpendicular orientation to flow line have a slightly higher stength than that from specimens cut in parallel orientation. Furthermore, specimen's fracture appearances at different strain rates were observed and compared, which demonstrate that as the strain rate increases, the smoothness of the fracture appearance is improved in tensile tests, and annular coarse grain is formed in compression tests. Based on the experimental data, J-C(Johnson-Cook) constitutive model was fitted.