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在Gleeble-1500热模拟机上对室温120°模具等径弯曲通道变形(ECAP)制备的平均晶粒尺寸为200nm的工业纯钛(CP-Ti)进行等温变速压缩实验,研究超细晶(UFG)工业纯钛在变形温度为298～673K和应变速率为10-3～100s-1条件下的流变行为。利用透射电子显微镜分析超细晶工业纯钛在不同变形条件下的组织演化规律。结果表明:流变应力在变形初期随应变的增加而增大,出现峰值后逐渐趋于平稳;峰值应力随温度的升高而减小,随应变速率的增大而增大;随变形温度的升高和应变速率的降低,应变速率敏感性指数m增加,晶粒粗化,亚晶尺寸增大,再结晶晶粒数量逐渐增加;超细晶工业纯钛热压缩变形的主要软化机制随变形温度的升高和应变速率的降低由动态回复逐步转变为动态再结晶。
The isothermal compression experiments of industrial pure titanium (CP-Ti) with an average grain size of 200nm prepared by ECAP at room temperature of 120 ° C were conducted on a Gleeble-1500 thermal simulator to investigate the effects of ultrafine-grained (UFG) The rheological behavior of industrial pure titanium under the deformation temperature of 298 ~ 673K and the strain rate of 10-3 ~ 100s-1. The microstructure evolution of ultrafine grained pure titanium under different deformation conditions was analyzed by transmission electron microscopy. The results show that the flow stress increases with the increase of strain at the initial stage of deformation, and gradually becomes steady after the peak appears. The peak stress decreases with the increase of temperature and increases with the increase of strain rate. The increase of strain rate, the increase of strain rate sensitivity index m, the coarsening of grain size and the increase of subgrain size and the increase of the number of recrystallized grains. The main softening mechanism of the ultrafine-graded industrial pure titanium during hot compression deformation varies with deformation The increase of temperature and the decrease of strain rate are gradually transformed from dynamic recovery to dynamic recrystallization.