Shi Limin, Wang Tong, Wang Liang, Liu Erliang
College of Mechanical and Power Engineering, Harbin University of Science and Technology, Harbin 150080, China.
School of Mechanical Engineering and Rail Transit, Changzhou University, Changzhou 213164, China.
Materials (Basel). 2023 Oct 16;16(20):6715. doi: 10.3390/ma16206715.
Due to its excellent physical properties, γ-TiAl alloy has been widely used in thin-walled components of aerospace engines. However, issues such as low thermal conductivity, poor machinability, and high cutting temperatures often result in difficulties in ensuring the geometric accuracy and surface integrity of the parts. This paper focuses on the study of the thermal deformation behavior of γ-TiAl alloy within a range of higher temperatures and strain rates. Firstly, by conducting quasi-static tests and Hopkinson bar tests on γ-TiAl alloy, the true stress-strain curves of γ-TiAl alloy are obtained within a temperature range of 20500 °C and a strain rate range of 300011,000/s. Based on the Johnson-Cook model, the true stress-strain curves are fitted and analyzed with consideration of the coupling effect of strain rate, temperature, and strain. The strain rate hardening coefficient C and thermal softening exponent m are polynomialized, improving the Johnson-Cook constitutive model of γ-TiAl alloy. The improved model shows significant improvements in the correlation coefficient and absolute errors between the predicted values and experimental values, providing a better reflection of the thermal deformation behavior of γ-TiAl alloy within a range of higher temperatures and strain rates.
由于γ-TiAl合金具有优异的物理性能，已被广泛应用于航空发动机的薄壁部件。然而，诸如热导率低、可加工性差和切削温度高等问题，常常导致难以确保零件的几何精度和表面完整性。本文着重研究γ-TiAl合金在较高温度和应变速率范围内的热变形行为。首先，通过对γ-TiAl合金进行准静态试验和霍普金森杆试验，在20500°C的温度范围和300011,000/s的应变速率范围内获得了γ-TiAl合金的真应力-应变曲线。基于约翰逊-库克模型，考虑应变速率、温度和应变的耦合效应，对真应力-应变曲线进行拟合和分析。将应变速率硬化系数C和热软化指数m多项式化，改进了γ-TiAl合金的约翰逊-库克本构模型。改进后的模型在预测值与实验值之间的相关系数和绝对误差方面有显著改善，能更好地反映γ-TiAl合金在较高温度和应变速率范围内的热变形行为。
