Comparison of The Fatigue Strength of Ti‐5553 And Ti‐6Al‐4V for Aerospace Applications

Abstract

In face of the potential application of the near-beta Ti-5Al-5Mo- 5V-3Cr alloy as a replacement for Ti-6Al-4V on landing gears and other structural components, the dynamic behavior of this metal is of high concern. The fatigue strength of the Ti-5553 alloy subjected to BASCA heat treatment is compared to the fatigue strength of conventional Ti-6Al-4V ELI following in a first approach the staircase method. Analysis of the fracture surfaces of the Ti-5553 alloy through scanning electron microscopy was performed for an initial investigation of the microstructural aspects on the fatigue behavior. Preliminary results suggest that the fatigue limit lies in the range of 650-700 MPa for Ti-5553 and 825-850 MPa for Ti-6Al-4V. Fracture surface of Ti-5553 exhibits a mixture of crystallographic cleavage and dimpled fracture, with striations in a small region near the initiation site, whereas sharp fatigue striations with strips is evidenced for Ti-6Al-4V.