工业纯钛低温拉伸和循环变形中的孪生行为

THE TWINNING BEHMIOUR DURING TENSION AND FATIGUE AT LOW TEMPERATURE IN COMMERCIAL PURITY TITANIUM

在－１９６℃下对钛进行了拉伸和低周循环变形，观察分析了变形后试样的微观组织结果表 明，工业纯钛在－１９６℃拉伸变形后，强度比在室温下拉伸变形有了明显的提高，塑性也有明显的增加； 在－１９６℃下循环变形时，循环应力－应变曲线位于－１９６℃静拉伸应力一应变曲线的上方，显示出明显 的循环硬化特征微观组织观察表明，一１９６℃拉伸及循环变形试样中存在着大量的李晶，且孪晶数量随 着循环应变幅及循环周次的增加而增加．在工业纯钛－１９６℃下的拉伸及循环变形中孪生起重要作用．

Tension and low cycle fatigue of commercial purity titanium at the temperature of ' -196 were carried out, and the corresponding microstructures were examined. The results showed that during tensile deformation at -196 , not only the tensile strength but also the elongation were improved comparing with that at RT. The cyclic stress increased with the increasing of cyclic number or cyclic strain amplitude, and the cyclic stress-strain curve was above the tension stress-strain curve, indicating the cyclic hardening happened during -196 fatigue in commercial purity titanium. The observation by OM and TEM showed that there existed a large amount of mechanical twins in the specimens deformed at -196 , implying that twinning played an important role in the processing of monotonic and cyclic deformation.