Abstract:

High?speed tensile tests of HC420/780DP dual?phase steel at strain rates of 0.001，0.100，1.000，10.000，100.000 s^－1 and 200.000 s^－1 were carried out. The dynamic mechanical behavior of the materials under different strain rates was studied. The true stress?strain curves of HC420/780DP at different strain rates were obtained, and the fracture elongation, tensile strength and flow stress were analyzed. The results show that the flow stress, yield strength and tensile strength of HC420/780DP dual?phase steel increased with the increasing strain rate. Based on the modified Johnson?Cook constitutive model, the dependent plastic deformation constitutive model versus HC420/780DP dynamic strain rate was established. The fitting results of the optimized constitutive equation are in consistent with the curves of experimental results.

Key words: HC420/780DP, High speed tensile tests, Dynamic mechanical properties, Strain rate, Modified Johnson?Cook constitutive model

摘要：

在应变率分别为0.001、0.100、1.000、10.000、100.000 s^－1和200.000 s^－1的条件下，测试了双相钢HC420/780DP的高速拉伸性能，研究了其在不同应变率下的动态力学行为，得到了不同应变率下的真应力?真应变曲线，分析了其屈服强度、抗拉强度、流变应力以及断裂延伸率随应变率的变化规律。结果表明，随着应变率的升高，双相钢HC420/780DP的屈服强度、抗拉强度和流变应力均有所升高，断裂延伸率呈现先升高后降低的趋势。另外，基于Johnson?Cook本构模型，建立并修正了双相钢HC420/780DP与动态应变率相关的塑性本构模型，并验证了修正后的模型。结果表明，通过修正得到的本构模型与试验曲线拟合效果较好。

关键词: HC420/780DP, 高速拉伸, 应变率, 动态力学性能, Johnson?Cook本构模型修正