Microstructural influences on fatigue crack propagation in Ti-10V-2Fe-3Al

Abstract

Tensile properties and Fatigue Crack Propagation (FCP) rates have been measured in laboratory air for a wide variety of different Ti-10-2-3 microstructures, all having nominal yield strengths of 1240 MPa. These microstructural variations included both recrystallized and unrecrystallized conditions, as well as varying amounts of primary α, both α- and Ω-aged conditions, and also several hot forming histories. With one exception, microstructure was found to have very little or no influence on FCP. Not only was the rate of FCP unaffected, but moreover, the macroscopic fracture surface roughness was largely unaltered. The one exception was a notable one: the Ω-aged condition. Strengthening through the precipitation of Ω instead of α was found to retard FCP significantly; no significant change in macroscopic fracture surface roughness was found, however. The retardation was attributed to changes in slip character and reversibility.