Microstructural effects on fatigue and dwell-fatigue crack growth in α/β Ti-6Al-2Sn-4Zr-2Mo-0.1Si

Abstract

This article presents the results of an experimental and theoretical study of the effects of microstructure on room-temperature fatigue and dwell-fatigue crack growth in Ti-6242. The crack growth rates and micromechanisms of long crack growth are elucidated for equiaxed, elongated, and colony microstructures. The article shows that dwell and pure fatigue crack growth rates are generally similar in the long crack growth regime. The underlying mechanisms of long crack growth are also generally similar under pure fatigue and dwell-crack growth conditions. However, differences in dwell and fatigue sensitivities are observed between the different microstructure in the mid-and high-ΔK regimes. These are explained by considering the possible interactions between fatigue and creep during dwell fatigue loading at room temperature. Linearized fracture mechanics crack growth laws are presented for the modeling of crack growth in the near-threshold, Paris, and high-ΔK regimes.