利用數字圖像相關方法研究了Ti80合金表面質量和缺口對其三點彎曲性能的影響,采用掃描電鏡及電子背散射衍射方法對斷口進行觀察。結果表明:表面拋光試樣的抗彎強度最大,表面打磨及缺口試樣的抗彎強度略有降低,沒有明顯的缺口強化效應,斷裂應變隨著表面質量的下降及缺口尺寸的增加而迅速減小;應力集中系數越大,試樣的變形區域越小,應變強化能力越弱;Ti80合金的斷口呈韌窩形貌,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.