中文摘要：

在20℃～800℃的温度范围和10^-3～10^4s^-1。的应变率范围内，采用电子万能试验机和分离式霍普金森压杆，对淬硬45钢（45HRC）分别进行准静态实验和动态压缩力学性能实验，得到应力应变曲线。结果表明：淬硬45钢的流动应力对应变率敏感性一般，但表现出较强的温度敏感性，随着应变率的增大而增大，随着温度的升高而降低。采用以高斯函数表示温度效应的改进Johnson-Cook本构方程拟合了淬硬45钢在高应变率和高温条件下的本构关系，拟合曲线与实验数据吻合较好。

英文摘要：

To explore the dynamic mechanical properties of hardened steel （45HRC）, quasi-static and dynamic compression experiments were performed in the temperature range from 20℃ to 800℃ and the strain rate range from 10^-3 s^-1 to 10^4 s^-1 by using an electronic universal testing machine and a split Hopkinson pressure bar system, respectively. And the stress-strain curves were experimentally obtained. The results indicate the flow stress of hardened 45 steel is not sensitive to strain rate, but sensitive to temperature. The flow stress increases with the increase of strain rate and decreases with the increase of temperature. The constitutive relationship of hardened steel （45HRC） under high temperature and high strain rate was fitted by the improved Johnson-Cook constitutive relationship in which the Gaussian function was used to describe the temperature effect. The fitted curve is in good agreement with the experimental data.