TC21合金的高温变形行为及其组织演变

Deformation Behaviors and Microstructure Evolution of TC21 Alloy in Hot Working

通过G leeb le压缩试验,系统地研究了TC21合金在α+β两相区、β单相区的热变形行为及其组织演变。对流动应力的分析表明,峰值应力与变形温度和应变速率间符合双曲正弦形式的Arrhen ius本构关系。变形死区的组织观察表明,随着变形温度的升高,合金中细小α相首先转变为β相;进入单相区后,取向相近的β晶粒间相互合并而迅速长大。应变速率对微观组织的形貌和尺寸有一定影响,在低应变速率时等轴α相的形貌并没有明显变化,变形以β相为主;随着应变速率的升高,α相沿轴向方向被压扁,β相呈现纷乱不均的分布;进入单相区后,粗大的β晶粒被压扁,并在晶界处生成新的等轴β晶粒。

The deformation behavior and microstructure evolution of the TC21 alloy with duplex structure were investigated in the α ＋ β zone and β zone by compression tests. According to the linear analysis, the hyperbolic sine constitutive equation was suitable for relationship among the peak stress, temperature and strain rate. In the dead zone, the fine α phase was primo-merged by β phase; in the β phase zone, the β grains with close orientation merged and grew up rapidly. The morphology and size of microstructure were impacted by strain rate. In low strain rate zone, the morphology of α phase was not obviously changed ; and the deformation of TC21 alloy was dominated by β phase. With the strain rate rising, the coordination ability of deformation became weakly between α and β phase, and the α phase was flattened in axial direction; the β phase confusedly distributed in the matrix. In the single β phase zone, the coarse β grains were flattened, and the new equiaxed β grains nucleated on the grain boundary.