Titanium Alloy Grade 5, commercially known as Ti‑6Al‑4V, is the most widely applied alpha‑beta titanium alloy in industries including aerospace, medical devices, offshore engineering, and automotive components. It is well‑recognized for its outstanding combination of high specific strength, excellent corrosion resistance, good fatigue performance, and favorable machinability and weldability. Its chemical composition is clearly defined by major international standards such as ASTM B265, ASTM B348, and AMS specifications, which strictly regulate both intentional alloying elements and residual impurity contents.
The primary chemical components of Grade 5 titanium alloy consist of titanium as the base element, with controlled additions of aluminum and vanadium as the principal alloying elements. Aluminum acts as an alpha‑phase stabilizer, effectively increasing the alloy's strength, elastic modulus, and creep resistance at moderately elevated temperatures. Vanadium serves as a beta‑phase stabilizer, improving room‑temperature ductility, toughness, and heat‑treatable response. According to standard specifications, the aluminum content is controlled within the range of 5.50% to 6.75% by weight, while the vanadium content ranges from 3.50% to 4.50% by weight.
Titanium accounts for the balance, typically making up more than 90% of the total composition, maintaining the alloy's inherent lightweight and corrosion‑resistant characteristics.
In addition to the main alloying elements, strict limitations are imposed on impurity elements to guarantee mechanical performance, structural stability, and processing reliability. Excessive impurities can lead to embrittlement, reduced ductility, impaired fatigue life, and increased risk of cracking during forming or welding. Key impurity elements include iron, oxygen, carbon, nitrogen, hydrogen, and other residual elements.
Among these, iron is limited to a maximum of 0.40%, as higher iron content may cause phase segregation and reduce corrosion resistance.
Oxygen, as an interstitial element, is restricted to 0.20% maximum; elevated oxygen levels significantly increase hardness but drastically lower ductility and fracture toughness.
Carbon is controlled to a maximum of 0.08% to prevent the formation of brittle titanium carbide particles that can initiate microcracks.
Nitrogen, similar to oxygen in its hardening effect, is limited to 0.05% maximum to preserve ductility and weldability.
Hydrogen is strictly limited to 0.015% maximum, as even small amounts can induce hydrogen embrittlement, which is particularly dangerous in structural and load‑bearing applications.
Other individual residual elements are generally limited to 0.10% each, with a total limit of 0.40% for all unspecified residual elements combined.
These compositional requirements ensure that Grade 5 titanium alloy achieves stable and predictable performance across various manufacturing processes and service environments. Whether used in forged bars, rolled plates, extruded profiles, or cast components, compliance with the specified chemical composition and impurity limits is essential for meeting industry standards and end‑use performance demands.
