Titanium has been used in the aerospace industry for some time now, redefining the equipment and its subsequent performance. Commercially pure titanium is preferred for the making of airframes, while titanium alloys are generally used for the development of engine parts.
An increased demand fueled by cost productivity
How did titanium become such a high-demand metal for aircrafts? Well, the expansion of titanium use in this industry has been fueled by the desire of improving costs. Titanium is lightweight, having a reduced density in comparison to steel. Thus, it could be used to reduce overall fuel consumption in various aircrafts.
Properties of titanium make it suitable for aircraft use
Titanium, as well as its alloys, has a number of particular characteristics, which make it an excellent choice for aircraft parts (high strength, corrosion resistance). It is also compatible with carbon fiber reinforced plastic – CFRP – which is often used in both airframes and engine parts (improved fuel consumption as a result).
The physical characteristics of titanium are similar to the ones of carbon fiber reinforced plastic, hence the excellent compatibility of these materials in airframes.
Titanium alloys are used for the development of turbo fan engines, especially for the actual fan and the associated compressor (temperature relatively low, at approximately 600 degrees Celsius).
The reason for which titanium alloys are preferred for aircraft engines has to do with their higher strength, in comparison to commercially pure titanium. These are lightweight, resistant to heat and have excellent fatigue strength.
Types of titanium used in the aerospace industry
Commercially pure titanium has good corrosion resistance and formability, being generally chosen for non-structural applications. For example, the water supply systems which have titanium in their structure present increased resistance to corrosion. The same goes for titanium piping and ducts.
These are the different types of titanium alloys and their subsequent use:
- Used for the airframes and engine parts
- Characteristics: high strength, weldability
- Structural material for bolts and seat rails
- Engines – fan blades, intake section (low temperatures)
- Characteristic: heat resistance
- Use – compressor discs
- Characteristic: heat resistance
- Use – compressor blades
- Characteristics: high strength, heat resistance, excellent fracture toughness
- Use – fan and shaft (one piece to reduce engine weight)
- Excellent crack propagation characteristic
- Characteristics: heat resistance, high strength
- Used in engines due to excellent creep characteristic
- Available in the form of a titanium sheet
- Strength higher than commercially-pure titanium
- Welded piping and ducts from grade 5 titanium sheet in airframes
- Characteristics: high strength, high fatigue strength, corrosion resistance
- Excellent hardenability
- Use – landing gear.
One of the main reasons for which titanium is selected for the making of airframes has to do with weight reduction objectives. Titanium is also resistant to heat and corrosion, not to mention is has a reduced risk of embrittlement (even at low temperatures) and a low thermal expansion.
The pure titanium sheets are used for the making of the nacelle, the housing that holds the engine (separately from the fuselage). The pylons that support podded or hanging engines can have parts made from titanium, while the titanium pipe is preferred so as to prevent freezing (hot air piping or bleed air tubes).
In deciding to use titanium for aircraft engines, the reliable performance remains a main point of interest. The titanium bar is commonly used for the development of the fan case, guaranteeing the increased resistance and associated performance. Titanium might also be used for the making of low-pressure compressor blades, as well as low-pressure stator vanes.
A particular use of titanium in aircrafts regards the landing gear, which everyone knows to be a vital component of any airplane. In recent times, even the landing gear beam has begun to be made from titanium. This is the element that connects the airplane wing to the landing gear, acting as a highly-efficient shock absorber.
Aircraft components that are subjected to high stress, such as the landing gear beam, most be designed in a manner that they resist an increased mechanical load. The use of titanium alloys for the making of such components is not a random thing; these have the high strength and fatigue resistance to meet the demands of the subsequent application.
What does the future hold for the use of titanium in the aerospace industry?
In the future, more and more aircraft parts will be made from titanium or titanium alloys. This metal delivers high strength, excellent corrosion resistance and superior performance. It can be used for both airframes and engine parts, causing an improvement whereas the aircraft fuel consumption is concerned.
Commercially-pure titanium is preferred for airframes, given the fact that it has a higher formability level. Titanium alloys, such as the ones mentioned above, are chosen for engine parts, due to their high heat resistance and strength. Additional aircraft components, such as fuselage parts, springs, tubes for pneumatic systems and flap tracks, are already manufactured from titanium.
Thanks to the 3D printing technology, which keeps on advancing, we are seeing more and more 3D-printed titanium parts being used for the construction of airplanes. Boeing, for example, has employed the use of such parts for the development of the 787 Dreamliner.
Titanium alloys are strong and lightweight, being able to reduce plane fuel consumption and improve cost productivity. However, they also cost more than aluminum and steel, causing manufacturers to worry about their use. 3D printing, on the other hand, might reduce manufacturing costs and increase the demand for titanium.
The 3D-printed parts have begun to be used for both non-structural and structural applications (load-bearing components). They are created with the help of a technique known as Rapid Plasma Deposition (RPD), in which a titanium wire is melted in an argon gas cloud. According to the manufacturers, this technique could improve both energy use and the costs of raw materials.
The aerospace industry will continue to rely on titanium and its alloys for the development of airframes and engine parts. Owing to the development of 3D printing, we will also see titanium being used for load-bearing components in commercial aircrafts. Titanium delivers the best performance, having high strength, a reduced weight and excellent corrosion resistance to offer.