Fatigue response, fracture characteristic and life modeling of a near-alpha titanium alloy under typical cyclic loadings in service

Experimental investigations on the fatigue behavior of a near-alpha titanium alloy under typical cyclic loadings were carried out to simulate the service loading states applied on the engine blades. The axial stress-controlled tension–tension low-cycle fatigue (LCF) tests were carried out over a range of maximum stresses and stress ratios. The rotary bending tests were conducted using a step-loading procedure to reveal the high-cycle fatigue (HCF) limit stresses. The cyclic softening effect is observed in this material, and the strain ratcheting occurs obviously at the maximum LCF loading of 900 MPa. The LCF resistance is found to be dependent on both the maximum loading and the stress ratio. The HCF limit stresses for 1 × 107 and 1 × 106 cycles are determined as 405.7 and 457.6 MPa, respectively. The macroscopic fatigue fracture mode and the failure features on fracture surfaces were analyzed by scanning electron microscope (SEM).