热氧化TC4静动态力学性能研究

Static and dynamic mechanical behaviors characterization of the oxidized TC4

摘要:

本文选取700 °C/10 h热氧化工艺,对TC4进行热氧化处理。通过准静态压缩,纳米压入及分离式Hopkinson压杆冲击等测试,研究了热氧化对TC4静动态力学性能的影响。此外,借助扫描电镜(SEM)分析了动态冲击后氧化层的形貌。结果表明,热氧化TC4具有较好的静态力学性能和较高的应变率强化效应。氧化层在较低冲击应变率下,能够提高TC4的塑性；而当应变率过大,则会降低其塑性。最后,经过对本构模型修正和试验数据拟合,得到了室温下的热氧化TC4的Johnson-Cook(J-C)本构方程。修正曲线与实验结果对比,两者在塑性平台区吻合较好。

Abstract:

Thermal oxidation process was performed on TC4 alloy for 10 h at the temperature of 700 °C. The static and dynamic mechanical behaviors of the thermal oxidized TC4 were investigated by quasi-static compression, nanoindentation and split Hopkinson pressure bar impact tests. Moreover, the micro-morphology of the oxide layer after impact tests was analyzed by scanning electron microscope (SEM). The results indicate that after thermal oxidation the static mechanical properties of TC4 is improved and its strain rate hardening effect is enhanced. Under a relatively low strain rate, the oxide layer could increase the plastic deformation ability of TC4. At a large strain rate, however, the oxidation layer reduces its plastic deformation ability. Through fitting of the impact test data and constitutive model correction, the Johnson-Cook (J-C) constitutive equation of the thermal oxidized TC4 is obtained. Compared to experimental results, the correction and experimental curves have a good agreement in the plastic deformation region.