材料超高温动态拉伸SHTB实验方法的有效性分析

针对高温拉伸分离式Hopkinson杆实验技术，通过数值模拟、实验验证以及几种典型材料的高温动态拉伸性能测试相结合的方法，对此实验技术中存在的几个关键问题进行了深入研究。结果表明:对于平板状钩挂式拉伸试样，通过标距段尺寸优化后，应力分布均匀，流动应力曲线与螺纹拉伸试样一致，且应力上升段后没有剧烈跳动；通过精确气动控制，在加载脉冲到来同时，可实现有效的试样快速同步组装和加载；当试样温度为1 200 ℃时，在冷加载杆与高温试样接触以及应力波加载试样的整个过程中，试样平均温度下降约1.3%，而加载杆端温升低于180 ℃。为了验证此实验技术，对3D打印TC4、镍基单晶高温合金DD6进行了最高温度约1 200 ℃时的高温动态拉伸力学性能实验测试。

Validity analysis of materials' dynamic tensile SHTB experimental technique at ultrahigh temperature

In this work we investigated several key issues in view of the dynamic tensile experimental technique used in the split Hopkinson tension bar at ultra high temperature by performing numerical simulation,experimental verification and tests of several typical materials' dynamic tensile property at high temperature.The results show that the stress distribution was uniform for the flat tensile specimen with a hook joint after its gauge section size was optimized.The flow stress curve of the hook joint flat tensile specimen coincided well with that of the thread specimen,and no evident shake was observed in the strain rising stage.Through accurate pneumatic control,effective rapid synchronous assembly and loading of the specimen could be achieved at the same time when the loading wave arrived.When the temperature of the specimen reached 1 200 ℃,the average temperature of the specimen only dropped about 1.3 ％ and the temperature rise of the loading bars kept below 180 ℃ during the whole cold contact between the high temperature specimen with the cold loading bars as well as in the process of the stress wave loading the specimen.To validate this experimental technique,tests were conducted at the temperature as high as about 1 200 ℃ for the dynamic tensile mechanical properties of a few materials such as 3D printed TC4 and single crystal nickel-base superalloy DD6.