工业纯钛室温下的应变速率敏感性及Hollomon经验公式的改进

通过实验研究了工业纯钛TA2在室温下应变速率范围为1×10-4～1×10-2s-1的拉伸力学性能。发现TA2的拉伸力学性能存在显著的应变速率敏感性,随着应变速率的增加,材料的强度提高、塑性下降,应变速率敏感性指数较高。通过对Hollomon经验公式σ=Kεnεm的推导和TA2实验数据的分析发现应变速率敏感性指数m和应变硬化指数n分别会受到应变和应变速率的影响,并且它们之间均呈指数关系。因此对Hollomon经验公式提出了改进,得到了TA2在室温下改进的Hollomon模型。与传统的Hollomon经验公式及Johnson-Cook模型相比,改进的Hollomon模型的预测结果与实验结果更加吻合,能更准确地表现材料的拉伸力学性能。

Strain Rate Sensitivity of Commercially Pure Titanium TA2 at Room Temperature and Revising of Hollomon Empirical Formula

The tensile mechanical properties of commercially pure titanium TA2 within the strain rate scope 1×10-4 ~1×10-2 s-1 have been tested at room temperature, and the stress-strain curves of different strain rates have also been obtained. The results show that the stress-strain curve of commercially pure titanium TA2 at room temperature is significantly sensitive to strain rate. The strength parameters such as flow stress increase with the higher strain rate, while the plastic parameters such as elongation and area reduction decrease. The strain rate sensitivity index of TA2 is great. Through the theoretical analysis of Hollomon empirical formula () and the experimental verification of TA2, it is found that the strain rate sensitivity index m and strain hardening index n are related with strain and strain rate, respectively and the relation between them is power equation. Therefore, the Hollomon empirical formula is revised, and the revised Hollomon equation of TA2 is obtained. Compared with traditional Hollomon empirical formula and Johnson-Cook model, the revised equation has better agreement with experimental results and can depict the tensile mechanical property of TA2 more accurately