Correlation Between Microstructure and Fatigue Property of Ti-6al-4v Alloy Used in Aerospace Applications

Abstract

Ti-6Al-4V is one of the most commonly used titanium alloys in the aviation industry due to its high strength-to-weight ratio, high operating temperature, and corrosion resistance. In this study, two batches of Ti-6.3Al-4.17V samples were subjected to different thermomechanical processes. The first batch was treated below the β-transus temperature (980 °C) to get duplex structure (α+β), while the second batch was treated above β-transus temperature (1050 °C) to get lamellar structure. Rotating bending fatigue test was carried out using electropolishing surface condition. It is observed that the treatment above β-transus showed higher fatigue limit than the samples treated below the β-transus. This is attributed to the fine structure (lamellar structure) obtained at 1050 °C than the duplex structure (α+β) obtained at 980 °C. In addition, the fatigue crack initiation sites existing in the structures were determined.