Ti-6.5Al-2Zr-1Mo-1V钛合金低温应力松弛及组织演变

在500、550和600 ℃及不同初始应力下对Ti-6.5Al-2Zr-1Mo-1V钛合金进行了应力松弛实验。基于经典的Maxwell指数衰减函数，得到了应力松弛极限。提出了利用松弛稳定系数（C_S）和松弛速率系数（C_R）来描述Ti-6.5Al-2Zr-1Mo-1V合金的松弛特性，有利于制定残余应力消减工艺。根据Norton和Arrhenius方程计算了应力指数。通过应力指数和显微组织分析，阐明了应力松弛机理。在不同初始应力下，500 ℃时，位错的攀移和扩散主导了应力松弛过程；550 ℃时，位错滑移在应力松弛过程中起主要作用；600 ℃时，位错滑移、边界滑移和晶粒旋转控制着松弛过程。

Low Temperature Stress Relaxation and Morphology Evolution of Ti-6.5Al-2Zr-1Mo-1V Titanium Alloys

Stress relaxation tests were performed on Ti-6.5Al-2Zr-1Mo-1V titanium alloys with different initial stresses at 500, 550, and 600 °C. Based on the classical Maxwell exponential decay function, the stress relaxation limit was obtained. The relaxation stability coefficient (C_S) and relaxation rate coefficient (C_R) were proposed to describe the relaxation characteristics and to further guide the residual stress reduction. The stress exponent was calculated according to Norton and Arrhenius equations. Both the stress exponent and microstructure were analyzed to illustrate the stress relaxation mechanism. Under different initial stresses, the dislocation climb and diffusion dominate the stress relaxation procedure at 500 °C; the dislocation slip plays a major role in stress relaxation at 550 °C; the dislocation slip, boundary slip, and grain rotation control the stress relaxation process at 600 °C.