【摘要】 在变形温度为193～298 K、应变速率为2000～3000 s^-1的范围内,对Ti6321钛合金进行动态压缩试验,研究温度和应变速率对材料力学性能和变形行为的影响。采用光学显微镜（OM）、透射电子显微镜（TEM）和电子背散射衍射（EBSD）表征和分析了合金的微观结构演变。结果表明,随着温度的降低和应变速率的增加,Ti6321钛合金的动态屈服强度和平均流动应力均增大,而断裂应变明显降低。采用Johnson-Cook本构方程预测了Ti6321钛合金在低温高应变速率下的力学行为,拟合结果与实验结果吻合较好。微观结构分析表明,随着变形温度的降低,{112■}和{101■}2种孪晶的含量明显增加,即变形机制逐渐由孪晶的辅助作用转变为孪晶占主导地位。更多还原

【Abstract】 Dynamic compression tests of Ti6321 titanium alloy were carried out in the temperature range from 193 K to 298 K and strain rate range from 2000 s^-1 to 3000 s^-1 to study the effects of temperature and strain rate on the mechanical properties and deformation behavior of the alloy. The microstructure evolution was observed and analyzed by optical microscope（OM）, transmission electron microscope（TEM） and electron backscatter diffraction（EBSD）. The results show that with decreasing temperature and increasing strain rate, dynamic yield strength and average flow stress of Ti6321 titanium alloy increase, while the fracture strain decreases obviously. Johnson-Cook constitutive equation is used to predict the mechanical behavior at low temperatures and high strain rates, and the fitting results are in good agreement with the experimental ones. Microstructural study shows that the content of the {112■} and {101■} extension twins increases significantly as the deformation temperature decreases. The deformation mechanism gradually changes from the auxiliary role of twins to the dominance of twins.更多还原