Surface Texture of Fretting Fatigue Damaged Shot Peened Titanium

摘要

Fretting fatigue damage occurs at the contact between two surfaces, when a static load perpendicular to the interface and a cyclic load parallel to the surfaces are present. The fretting fatigue damage occurring on the surface is known to be responsible for initiation of surface breaking cracks and dramatic reduction of fatigue life of the materials and components. Many premature failures of the engine components of advanced fighter aircrafts have been attributed to the fretting fatigue damage. Though fretting fatigue damage occurs at the surface, NDE techniques have limited success in detecting early stages of damage. This paper presents a methodology based on optical profiling of the surface to evaluate the progression of damage in fretting fatigue damaged specimens of shot peened Ti-6Al-4V. Surface topography measurements performed using a white light interference microscope were analyzed to identify the surface texture parameters sensitive to progressive damage. Results of the relation between the number of fretting fatigue cycles, surface texture parameters, residual stress and the changing microstructure are presented. Potential of the optical surface profiling as a nondestructive evaluation tool for characterization of the fretting fatigue damage is discussed.