HCF properties of laser deposited Ti-6Al-2Zr-Mo-V alloy

Fatigue failure is the most important failure mode in industrial applications of titanium alloys while fatigue strength is the critical mechanical property. First, the fatigue properties of laser deposited Ti-6Al-2Zr-Mo-V alloy are studied. High-cycle fatigue (HCF) test is conducted at room temperature at several different stress levels ranging from 625 MPa to 900 MPa, with a load ratio of 0.1 and a frequency of 120-130 Hz. Fatigue fracture surface is analyzed by scanning electron microscope (SEM). Then, the influence of micropores and their distribution on fatigue properties of laser deposited Ti-6Al-2Zr-Mo-V alloy is investigated. Fine α/β lamellar structure is obtained in laser deposited Ti-6Al-2Zr-Mo-V alloy. The examination results of high-cycle fatigue tests indicate that although micropores exist in the fatigue crack initiation regions, laser deposited Ti-6Al-2Zr-Mo-V alloy still has excellent fatigue properties. The fine α/β lamellar structure can effectively lend to the reduction of slip length in the crack initiation regions. Furthermore, the results also show that there is certain influence of stress level on fatigue behavior.