Effect of Cooling Rate on Beta Annealed High-Strength Airframe Titanium Alloys
Matias Garcia-Avila, Ph.D.
Allegheny Technologies Incorporated
High-strength titanium alloys such as Ti-10V-2Fe-3Al (Ti-10-2-3) and Ti-5Al-5V-5Mo-3Cr (Ti-5553) are currently used in airframe applications such as landing gear and other high strength components. These alloys exhibit tensile strengths around 180 ksi in the solution treated and aged condition, but tend to have low fracture toughness in the high-strength condition. In the beta annealed condition, fracture toughness is increased at the cost of reduced tensile strength. The cooling rate of Ti alloys from the beta phase field influences microstructure evolution, and has a direct impact on mechanical properties. In this study, the effect of cooling rate from the beta phase field on the microstructure and resulting tensile strength and fracture toughness of a variety of Ti alloys has been explored. This will provide an insight into the optimal heat treatment and microstructure to maximize strength-toughness relationships of structural Ti alloys.