(1. 东北大学 材料科学与工程学院,沈阳 110006;
2. 西北有色金属研究院 钛合金研究院,西安 710016)
摘 要: 利用平面应变压缩实验,研究TC21G钛合金在变形温度为870~940 ℃、应变速率为0.1~1 s-1条件下的变形行为,并分析显微组织的演变过程。同时,研究加工参数对应变硬化指数n值的影响。结果表明:在应变速率一定的条件下,随着变形温度的升高,显微组织中β相的含量增加,合金的流变应力降低;而在变形温度一定的条件下,随着应变速率的增加,可动位错的迁移速率增加,从而使合金的流变应力升高。TC21G钛合金在两相区进行变形,随着变形温度的升高,应变量的增加以及应变速率的降低,片层α相的球化程度增加。基于显微组织的分析可知,应变硬化指数n值与绝热升温效应,β相的动态再结晶(DRX)以及动态回复(DRV)有密切的关系。
关键字: TC21G钛合金;平面应变压缩;动态再结晶;应变硬化指数
(1. School of Materials Science and Engineering, Northeastern University, Shenyang 110006, China;
2. Titanium Alloy Research Institute, Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China)
Abstract:The hot deformation behavior in plane strain compression of the TC21G titanium alloy was investigated in the deformation temperatures ranging from 870 ℃ to 940 ℃, the strain rates ranging from 0.1 s-1 to 1 s-1. The microstructures evolution was also analyzed. Meanwhile, the effect of processing parameters on the strain hardening exponent n was analyzed. The results show that, under the condition of a certain strain rate, the flow stress of alloy decreases with the increase of the deformation temperature due to the increase of β phase content. However, in the condition of a certain temperature, the flow stress of alloy increases with the increase of the strain rate, because the velocity of mobile dislocations increases. During deforming in the α+β field, with the increase of the deformation temperature or strain, and the decrease of the strain rate, the globularization degree of the lamellar α phase increases. Based on the microstructure examination, the variation of n values is found to depend on the adiabatic heating effect, dynamic recrystallization (DRX) and dynamic recovery (DRV) of β phase.
Key words: TC21G titanium alloy; plane strain compression; dynamic recrystallization; strain hardening exponent