利用数字图像相关方法研究了Ti80合金表面质量和缺口对其三点弯曲性能的影响,采用扫描电镜及电子背散射衍射方法对断口进行观察。结果表明:表面抛光试样的抗弯强度最大,表面打磨及缺口试样的抗弯强度略有降低,没有明显的缺口强化效应,断裂应变随着表面质量的下降及缺口尺寸的增加而迅速减小;应力集中系数越大,试样的变形区域越小,应变强化能力越弱;Ti80合金的断口呈韧窝形貌,存在大量的小角度晶界。

The effects of surface quality and notch on the three-point bending properties of Ti80 alloy were studied by digital image correlation method. The fracture surface was observed by scanning electron microscopy and electron backscatter diffraction. The results show that the bending strength of the surface polished sample was the largest, the bending strength of the surface polished and notched samples decreased slightly, and there was no obvious notch strengthening effect. The fracture strain decreased rapidly with the decrease of surface quality and the increase of notch size. The larger the stress concentration factor, the smaller the deformation area and the weaker the strain hardening ability of the sample. The fracture morphology of Ti80 alloy was dimple, and there were a large number of low angle grain boundaries.