Anisotropy of Rotating Bending Fatigue Properties of α+β Titanium Alloy

Abstract:

The effects of microstructure and texture on the rotating-bending fatigue anisotropy of an α+β two-phase titanium alloy by β forging was investigated. The microstructure and texture distribution of forged billet in different directions and thicknesses were characterized by OM, SEM, XRD and EBSD, and the effects of microstructure and texture on the rotating-bending fatigue anisotropy were analyzed. The results show that after β forging, the alloy has the characteristics of basket-weave microstructure, the prior β grains are flattened and elongated, and there are recrystallized grains at the grain boundary. The texture of β-phase <100>// axial direction and α-phase <0001>// radial direction formed by forged billet after β forging. The rotarting-bending fatigue strength of radial direction samples is better than that of axial direction samples, which are related to the morphology and texture type of the prior β grains of forged billet. The arrangement of the prior β grains leads to different initiation of cracks and different tortuous degree of crack growth path. In addition, the α and β textures also cause the fatigue strength differences due to the difficulty of slip systems activation of samples in different directions under cyclic loading.