TC4 titanium alloy (internationally recognized grade Ti-6Al-4V) is a highly mature and widely used (α+β) duplex titanium alloy, accounting for 50% to 85% of the total titanium alloy consumption. Thanks to its outstanding comprehensive performance, it has become a critical material in aerospace, biomedical, and industrial applications.

Here's an overview of the core properties of TC4 titanium alloy:

A Comprehensive Analysis of TC4 Titanium Alloy

1 Chemical Composition and Microstructure

• The compositional design of TC4 alloy is highly sophisticated. Aluminum (Al), as an α-phase stabilizing element, significantly enhances the alloy's strength and thermal stability through solid-solution strengthening. Meanwhile, vanadium (V), serving as a β-phase stabilizer, primarily improves the alloy's ductility, toughness, and hot-workability. The synergistic effect of these two elements enables TC4 to form a stable α-β duplex microstructure in the annealed state, striking an optimal balance between high strength and excellent toughness.

2 In-depth Analysis of Mechanical Properties
The mechanical properties of TC4 titanium alloy can be adjusted over a wide range through heat treatment processes, which is one of the key reasons for its widespread application.

• Basic performance: In the annealed condition, its typical tensile strength is above 895 MPa, with a yield strength ≥825 MPa, while maintaining an elongation of ≥10% and a reduction in area of ≥25%.
• Enhanced performance: By employing a process of solution treatment followed by aging, the tensile strength can be increased to around 1100 MPa, though this will result in a corresponding reduction in ductility.
• Strength-to-weight advantage: Its standout feature lies in its high strength-to-weight ratio—specifically, a value of 23.5, which is significantly higher than that of alloy steel (around 18), making it one of the ideal materials for lightweight design.

3 Physical and Chemical Properties
3.1 Physical Properties

• Among the physical properties of TC4, its lower elastic modulus (approximately 110 GPa, about half that of steel) and reduced thermal conductivity (7.955 W/m·K, roughly one-fifth that of iron) stand out prominently.
• A lower elastic modulus results in mechanical properties similar to those of human bone in biomedical applications, which can reduce the "stress shielding" effect and promote both bone healing and long-term stability.
• Low thermal conductivity means heat doesn’t dissipate easily during machining, which can lead to excessive tool heating—but it also makes the material perform well in applications requiring thermal insulation.

3.2 Corrosion Resistance

• TC4 titanium alloy exhibits excellent corrosion resistance, primarily due to the dense and stable oxide film (TiO₂) formed on its surface. It demonstrates outstanding performance in most acidic and chloride-containing environments, such as seawater and moist chlorine gas. In the petrochemical industry, corrosion-resistant valves and pump components made from TC4 typically offer a significantly longer service life compared to those made from stainless steel.

4 Detailed Applications
4.1 Aerospace Sector
This is one of the largest application markets for TC4 alloy.

• Application areas: Widely used in the manufacturing of aircraft engine fans, compressor disks and blades, airframe structural components (such as frames, skins, and landing gear parts), as well as various critical load-bearing elements for rockets and spacecraft, and liquid hydrogen fuel tanks, among other applications.
• Core Value: By using TC4, aircraft structures can achieve a weight reduction of 30%–40%, which is crucial for improving fuel efficiency and increasing payload capacity.

4.2 Biomedical Field
TC4 has become a commonly used material for surgical implants due to its excellent biocompatibility (non-toxic and non-sensitizing to human tissues), corrosion resistance, and suitable elastic modulus.

• Typical products include those used in the manufacture of artificial hip joints, knee joints, shoulder joints, dental implants, as well as bone trauma products such as bone plates and bone screws.

5 Processing and Handling Technologies
5.1 Machining Characteristics
The machinability of TC4 titanium alloy presents certain challenges.

• Processing recommendation: Typically, use a lower cutting speed, a larger feed rate, and apply ample coolant to effectively reduce the temperature.

5.2 Surface Modification Techniques

• To further enhance the surface properties of TC4 alloy—such as hardness and wear resistance—surface modification techniques like ion implantation can be employed. Studies have shown that after (N⁺ + N₂⁺) mixed-beam ion implantation, the microhardness of TC4 is effectively improved, while also helping to reduce the coefficient of sliding friction.

6 Special Properties and Cutting-Edge Research
Additive Manufacturing (3D Printing) Applications
When TC4 is used in the form of spherical metal powder for additive manufacturing processes such as SLM and EBM, or for powder metallurgy techniques like MIM, its performance shares similarities with traditional forged components, while also exhibiting differences arising from the specific manufacturing methods.

• Advantages: It can produce components with complex geometric shapes, and material utilization is high.
• Challenge: Rapid cooling may lead to the formation of fine, needle-like martensite α' phases, which, while offering high strength, could compromise ductility.
• Solution: An appropriate post-heat treatment, such as annealing, can transform the material into a balanced α+β duplex microstructure, optimizing its overall performance. Additionally, hot isostatic pressing helps eliminate internal defects and enhance density.

7 Summary and Outlook

TC4 (Ti-6Al-4V) titanium alloy, as a representative material among (α+β)-type titanium alloys, has become one of the key materials in modern industry—particularly in high-tech fields—thanks to its excellent strength, low density, outstanding corrosion resistance, and biocompatibility.

In the future, as materials science and technology continue to advance, the performance of TC4 titanium alloy is expected to be further optimized through innovative heat treatment processes, refined alloy compositions, cutting-edge manufacturing techniques such as additive manufacturing, and the application of advanced computational simulation tools. This will broaden its potential applications even further, enabling it to play a vital role in driving technological progress and improving human health standards.

References

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