Titanium metals make sense in aviation because of their attractive mechanical properties. A unique combination of physical and mechanical properties along with resistance of corrosion makes titanium ideal for aerospace demands.
Titanium's high strength-to-density ratio meets the needs for airframe components and structures. Couple this with the resistance to corrosion and erosion that titanium offers and the metal is a dream come true. High strength titanium alloys prove superior when compared to aluminum alloys and structural steels. This holds true even as service temperatures increase. Additionally, titanium alloys provide attractive high temperature properties for application in auto engine components or hot gas turbine components.
Within the family of titanium alloys, a wide spectrum of strength and combinations of strength are offered. This allows critical components to be tailored to through optimal alloy selection. To accommodate needs, one must consider the crack growth and toughness, such as critical flaw size, or the strength and S-N fatigue. Being relatively unaffected by environments and seawater prove that the S-N fatigue strength of titanium alloys is high enough to be usable not only in aviation but by marine industries as well. Good SCC resistance is another trait of titanium alloys as most can be processed in order to supply high fracture toughness along with minimal environmental degradation when required.
An invisible, thin surface oxide film provides an extremely protective surface for titanium alloys. This enables the alloys to exhibit extraordinary resistance to an immense range of chemical environments and conditions. The film is comprised mostly of TiO2, and is highly adherent, tenacious and chemically stable. Furthermore if mechanically damaged the film can instantaneously and spontaneously re-heal itself using the least traces of moisture or oxygen presented in the environment. Titanium is specifically useful in aviation due to its superior resistance to localized attack and stress corrosions in hot, highly-oxidizing, acidic solutions when compared to those that cannot withstand severe attack, such as nickel- or copper- based alloys, stainless steels and most steels.
Titanium is a preferred and well-established heat transfer material. Heat exchangers such as plate/frame, shell/tube and others make titanium ideal for process fluid cooling and heating. Additional characteristics that make titanium optimal include a surface that promotes condensation, a very thin and conductive oxide surface film, strength, difficult-to-adhere-to surface (because of hardness and smoothness), resistance to fluid erosion and corrosion. With these attributes, overall initial life cycle costs, material requirements and heat exchanger size are reduced and more cost effective.
So next time you see a jet flying overhead or are boarding a plane for vacation, remember that you likely have titanium to thank. This remarkable metal not only makes air travel possible but helps make it safer as well.