Application of titanium in aerospace industry: full analysis of performance advantages and key areas

The application of titanium in aerospace industry stems from the perfect combination of its four major performance advantages of "lightweight, high strength, high temperature resistance and corrosion resistance".

In key parts such as fuselage skin, wing structure, engine blades, high-pressure valves, landing gear and fasteners, titanium alloys can not only effectively reduce the weight of aircraft and improve fuel efficiency, but also maintain excellent mechanical properties and fatigue resistance in a wide temperature range of −60 °C to 600 °C.

At the same time, the dense oxide film on the surface gives titanium excellent corrosion resistance, allowing it to serve reliably in harsh environments such as marine climate, high humidity and high acid.

This article will focus on why titanium is widely used in the aerospace industry, the classification and common alloys of titanium and titanium alloys, and specific application parts. I hope everyone can understand the application of titanium in aerospace industry.

1. Why is titanium widely used in the aerospace industry?

The application of titanium in aerospace industry is essentially a perfect match between material properties and industry needs.

(1) Excellent specific strength

Titanium alloy has extremely high specific strength (specific strength = strength/density), which can ensure strength while reducing weight to the greatest extent. Compared with common aviation aluminum alloys, titanium alloy can significantly reduce the weight of the fuselage and structural parts under the same load, thereby reducing fuel consumption and operating costs.

(2) Excellent corrosion resistance

A dense oxide film will form on the surface of titanium, making it extremely resistant to corrosion in the atmosphere, seawater and various chemical media. This feature has expanded the application of titanium in aerospace industry to salt spray environments and high-temperature environments containing moisture and acid. 

(3) Excellent high-temperature performance

The melting point of titanium alloy is as high as 1668 °C, and it still maintains a high specific strength in the range of 300-600 °C. Unlike aluminum alloys, whose strength drops sharply above 200 °C, titanium alloys have better thermal stability in high-temperature parts such as engine high-pressure compressors and turbine blades.

Application of titanium alloys in engine high pressure compressor and turbine blades

(4) Good fatigue and creep resistance

Aerospace structural parts are subjected to alternating loads and high temperatures for a long time. The fatigue strength and creep resistance of titanium alloys are better than those of aluminum alloys. At the same time, the creep resistance in high temperature environment makes it the best choice for high-pressure components in engines.

2. Application of titanium in aerospace industry: material classification and introduction to commonly used alloys

Titanium and titanium alloys can be divided into six categories according to their organizational phases (α phase, β phase and mixed phases of the two). Different types of alloys have achieved the full spectrum of titanium applications in the aerospace industry from fuselage skin to engine high-temperature blades through the regulation of phase composition and microstructure.

(1) Classification of titanium and titanium alloys

1) Commercially pure titanium (CP-Ti)

Definition: Pure titanium that contains almost no alloying elements and only very small amounts of impurities (O, Fe, C, etc.).

Features: Excellent corrosion resistance and formability, often used in structural parts and chemical protection parts that do not require high strength but are critical to corrosion resistance.

2) α alloy

Definition: With α phase Ti as the matrix, trace amounts of Al, Sn, Pd and other stabilizing α phase elements are added, and only α phase exists at room temperature.

Features: Good high temperature creep resistance and corrosion resistance, but cannot be hardened by heat treatment, plasticity and toughness are slightly worse than α+β alloy, mainly used for high temperature structural parts at 200–400 °C.

3) Near α alloy

Definition: Add a small amount of β phase stabilizer (such as Mo, Zr) to the α alloy, almost all α phase at room temperature, only containing a small amount of β phase.

Features: Taking into account the high temperature performance of α alloy and the plasticity and toughness brought by some β phase, it is suitable for 400–500 °C parts, such as turbine stators and medium temperature discs.

4) α+β alloy

Definition: Contains both α and β phases, and can greatly control the mechanical properties through heat treatment. It is the most widely used type of titanium alloy.

Features: It can be hardened by heat treatment, has a wide strength range (600-1200 MPa), has good formability and weldability, and is the main alloy type for titanium in aerospace industry.

Titanium Alloy Rod

5) Near-β alloy

Definition: It is based on β phase, contains a small amount of α phase stabilizer, and has a structure close to the full β phase.

Features: The strength can be further improved by solid solution + aging, and the plasticity and processability are better than the full β alloy. It is often used in occasions where high strength and complex part shapes are required.

6) β alloy

Definition: It is mainly composed of β phase Ti, with β phase stabilizers such as Cr, Mo, and V added, and the room temperature structure is mainly β phase.

Features: It can be heat treated to obtain extremely high strength (up to 1400 MPa), with optimal plasticity and toughness, but it is difficult to form and process. It is mainly used for high-strength fasteners and thin-walled high-pressure components.

(2) Commonly used titanium alloys in aerospace

1) Ti-6Al-4V (Grade 5)

Category: α+β alloy

Composition: about 6% Al, 4% V, balance Ti

Performance: strength 600–950 MPa, good toughness and fatigue performance, good corrosion resistance; hardness and toughness can be flexibly controlled by heat treatment (O, β treatment).

Application: fuselage structural parts, landing gear components, fuel lines, engine low-pressure compressor blades.

Machining Ti-6Al-4V engine low pressure compressor blades

2) Ti-6Al-4V ELI (Grade 23)

Category: α+β alloy (low inclusion grade)

Features: lower oxygen, nitrogen and other impurities than standard 6-4, significantly improved fracture toughness; commonly used in life-critical and high-reliability components, such as flight control system connectors.

3) Ti-3Al-2.5V

Category: α+β alloy/near β alloy

Composition: 3% Al, 2.5% V

Performance: Strength 520–830 MPa, excellent low-temperature toughness and impact resistance, commonly used in aerospace cryogenic structures and propulsion systems.

4) Ti-6Al-2Sn-4Zr-2Mo

Category: Near α alloy

Features: Maintains good strength and creep resistance near 500 °C, suitable for engine medium-temperature components and turbine stators.

5) Ti-6Al-2Sn-4Zr-6Mo (Ti 6246)

Category: Near α alloy

Performance: Can be used at 550–600 °C, excellent creep resistance and high-temperature fatigue performance, mostly used for high-pressure compressor discs and discs.

6) Ti-17 (Ti-5Al-2Sn-2Zr-4Cr-4Mo)

Category: α+β alloy/near β alloy

Performance: Strength 800–1100 MPa, excellent high temperature fatigue and oxidation resistance at 300 °C; mainly used in medium and high pressure compressors and high temperature load-bearing parts.

7) β alloy (such as Ti-10V-2Fe-3Al)

Category: β alloy

Features: extremely high strength (up to 1200–1400 MPa), but poor plasticity and formability, often limited to bolts, fasteners and thin-walled high-pressure pipes.

3. Specific applications of titanium in aerospace industry

(1) Fuselage and wing structural parts

Titanium alloy plates, profiles and forgings are used to manufacture wing beams, skins, reinforcement beams and other main load-bearing structures. They are widely used because they maintain stable mechanical properties in a wide temperature range from -60 °C to +80 °C.

(2) Engine blades and disks

Ti-6Al-4V is commonly used for inlet and low-pressure compressor blades; high-temperature titanium alloys such as Ti-6Al-2Sn-4Zr-6Mo and Ti-17 are used for high-pressure compressors, turbine blades and disks to resist high-temperature loads above 500 °C.

(3) Landing gear and fasteners

Landing gear structural parts and supporting parts require high strength and good fatigue resistance. Ti-6Al-4V and high-strength CP-Ti are used to manufacture struts, pins and connectors; fasteners use titanium's corrosion resistance and high tensile strength to ensure long-term reliability of the fuselage interface.

(4) Spacecraft and missile components

In spacecraft structures and propulsion systems, titanium alloys are used to manufacture tank barrels, node joints and cooling devices due to their low-temperature toughness and stability under high vacuum. At the same time, Ti-3Al-2.5V and others are used in cryogenic fuel pipelines and oxidizer delivery systems.

Rocket engine structure and thrust chamber nozzle (Ti-6Al-4V)

(5) Special functional parts

Titanium alloys are also used in electronic heat sinks, chemical protective coating substrates, and the application of shape memory alloys (Nitinol) in micro-launch mechanisms in aircraft due to their biocompatibility and high specific strength.

4. Summary

The application of titanium in aerospace industry has always evolved with technological breakthroughs. This "space metal" continues to break the "weight-strength-environment" contradiction in aircraft design with its unique performance code, and has become a core material that supports the aerospace industry to continuously surpass its limits.

With the emergence of new alloys and processing technologies, the application of titanium in aerospace industry will surely open up a broader imagination space in the fields of hypersonic flight and deep space exploration.