Mechanisms Governing Fatigue, Damage, and Fracture of Commercially Pure Titanium for Viable Aerospace Applications

Abstract

In this paper, the cyclic stress amplitude controlled high-cycle fatigue properties and final fracture behavior of commercially pure titanium (Grade 2) are presented and discussed. The material characterization was developed and put forth for selection and use in a spectrum of applications spanning the industries of aerospace, defense, chemical, marine, and commercial products. Test specimens were prepared from the as-received plate stock of the material with the stress axis both parallel (longitudinal) and perpendicular (transverse) to the rolling direction of the plate. The test specimens were cyclically deformed at a constant load ratio of 0.1, at different values of maximum stress, and the corresponding cycles-to-failure is presented. The cyclic fatigue fracture surfaces were examined in a scanning electron microscope to establish the macroscopic fracture mode, the intrinsic features on the fatigue fracture surface, and the role of applied stress-microstructural feature interactions in governing failure. The intrinsic features on the fracture surface as a function of maximum stress and resultant cyclic fatigue life are discussed.