针片Ti-5Al-5Mo-5V-3Cr-1Zr热加工过程中的球化动力学及有限元仿真（英文）

Dynamic Globularization Kinetics and Finite Element Analysis for the Hot Working of Ti-5Al-5Mo-5V-3Cr-1Zr with Initial Lamellar Microstructure

为了预测初始层状α的Ti-55531(Ti-5Al-5Mo-5V-3Cr-1Zr)的微观组织演变,采用Avrami方程对Ti-55531热变形过程中的动态球化动力学模型进行了表征。为了确定方程的参数,为了获得应力-应变(σ-ε)曲线进行了一系列热模拟实验。通过进一步将σ-ε曲线转化为应变硬化速率dσ/dε-ε曲线,可以获得临界应变ε_c(对应dσ/dε的最小值)和峰值应变ε_p(dσ/dε=0时的应变)。还测量了不同变形条件下的动态球化分数f_g。接下来,通过线性拟合应变率,温度和动态球化部分之间的关系来确定Avrami方程中的参数。得到的Avrami方程表示为f_g=1–exp[–0.5783((ε–ε_c)/ε_c)^(0.907)],其中ε_c=3.315ε_p,ε_p=1.249×10^(-4)e^(0.0807)exp(58580/RT)。最后,将获得的动态球化动力学模型植入有限元程序中模拟动态球化动力学。将动态球化动力学模型与有限元方法相结合,有效地预测了针片α动态球化动力学过程。

To predict the microstructure evolution of the Ti-55531(Ti-5Al-5Mo-5V-3Cr-1Zr) with initial lamellar a, the dynamic globularization kinetics model of Ti-55531 during hot deformation was characterized by Avrami equation. A series of thermal simulation experiments were conducted to obtain the curves of stress σ versus strain ε to determine the equation parameters. By further transforming the stress-strain(σ-ε) curves into strain hardening rate dσ/dε-ε curve, the critical strain εc(corresponding to the minimum value of dσ/dε) and the peak strain εp(the strain at dσ/dε=0) were obtained. The dynamic globularized fraction fg at different deformation conditions was also measured. Sequentially, the parameters in the Avrami equation were determined from the linear fitting of the relationships among strain rate, temperature, and dynamic globularized fraction. The as-obtained Avrami equation was expressed as fg=1-exp[-0.5783((ε-εc)/εc)^0.907], where εc=3.315εp and εp=1.249×10^-4ε^0.0807 exp(58580/RT). Finally, the as-obtained dynamic globularization kinetic model was implanted into finite element program to simulate dynamic globularization kinetics. By combining the dynamic globularization kinetics model with the finite element method, the dynamic globularization of the lamellar a was predicted effectively.