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

Abstract

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.