Relationship between Microstructure and Fatigue Properties of Forged Ti–5Al–2Sn–2Zr–4Mo–4Cr for Aircraft Applications

Titanium alloys have applications in air frames for commercial aircraft, and jet engine components such as fans and compressor disks, which function at low temperatures (up to 673 K). Near β-type Ti–5Al–2Sn–2Zr–4C–4Mo (Ti-17) exhibits greater strength, crack propagation resistance, and creep resistance at intermediate temperatures compared to the (α + β)-type Ti–6Al–4V. It is important to estimate the fatigue life of engine components made of Ti-17. This requires problem quantitative relationship between the fatigue properties and microstructural factors of Ti-17. Therefore, the fatigue properties including tensile properties and microstructures of Ti-17 samples fabricated by hot-forging at various temperatures, followed by high- and low-temperature solution treatment (ST), and same aging treatment were investigated to define a quantitative relationship between the fatigue properties and the microstructures.