【摘要】 为了研究QP980钢在高应变率拉伸下的相变规律,在通常的Hopkinson拉杆装置入射杆和透射杆之间增加应变受控装置,根据试件应变预值设计装置尺寸,进行应变受控Hopkinson拉伸试验。利用回收试件进行X射线衍射试验,分析试件中应变对残余奥氏体体积含量的影响规律。分析发现QP980钢中残余奥氏体体积含量随着应变量的增加而呈非线性下降的趋势,结果表明,高应变率拉伸下残余奥氏体体积含量随着应变量增加的变化规律与准静态拉伸下的变化规律几乎一致。根据Olson和Cohen建立的马氏体相变动力学理论,结合X射线衍射试验结果得到了单轴拉伸下QP980钢中残余奥氏体体积含量和等效塑性应变的关系函数。更多还原

【Abstract】 An interruption mechanism is developed to control the elongation of specimens at high strain rate using a interrupted tensile split Hopkinson bar( ITSHB). The interruption mechanism is based on the interaction between the specimen and the external interruption device. The specimens of QP980 steel recorded from the interrupted TSHB tests are measured by using synchrotron X-ray diffraction( XRD) to analyze the volume fraction of retained austenite under uniaxial tensile state. It is revealed that the retained austenite volume fraction as a function of strain under the static loading is almost identical with that at the strain rates of 500 s-1and 1 000 s-1. The phase transformation kinetics equation of QP980 steel is constructed based on the O-C theory and the experiment results.更多还原