Grade 9 titanium alloy is an advanced α-type titanium alloy with a chemical composition of Ti-3Al-2.5V. It is an alloy developed for cold-workable pipe applications. At room temperature and high temperature, the strength of Grade 9 titanium alloy is 20%-50% higher than that of pure titanium, and its welding performance and cold forming performance are also better than TC4 alloy. Its maximum operating temperature is approximately 315°C. Due to its lower Al and V content, this alloy is also known as “Half 6-4”.

Grade 9 titanium alloy has excellent corrosion resistance, which can be further improved by adding a small amount of 0.05% Pd or 0.1% Ru. Although Grade 9 titanium alloy is not as strong as TC4 alloy, it is widely used due to its excellent cold working properties.

Grade 9 titanium alloy seamless pipe is suitable for hydraulic and fuel line systems in aircraft and engines, and has been used in a variety of military and civilian aircraft and aerospace applications. In addition, the alloy can also be rolled into foils and strips, with foils often used in areas such as honeycomb structures for aircraft.

Chemical composition of Grade 9 titanium alloy (%)








Other individual

Other total








≤ 0,015





Mechanical properties of Grade 9 titanium alloy


620 MPa


530 Mpa

Poisson’s ratio






Physical Properties of Grade 9 Titanium Alloy

Density: 4.47g/cm’,

elastic modulus at room temperature 118~123GPa,

phase transition point: 925℃,

hardness 15~17HRC.

Heat treatment system for Grade 9 titanium alloy

The heat treatment system of Grade 9 titanium alloy mainly includes two steps: annealing and stress relief annealing.

1) Annealing: Annealing of pipes and plates needs to be carried out in a vacuum furnace, and the absolute pressure in the furnace should not be higher than 0.09Pa. The heating temperature range is 650-790℃, and the furnace temperature fluctuation range is ±15℃. The holding time is 30-120 minutes, followed by furnace cooling.

2) Stress relief annealing: Carry out in accordance with the provisions of GJB 3763-1999 “Specifications for Heat Treatment of Titanium and Titanium Alloys”. The temperature range is 370-600℃, and the holding time is 15-240 minutes. Cooling can choose air cooling or furnace cooling.

It should be noted that when performing heat treatment, relevant specifications and standards should be strictly followed to ensure the control and monitoring of the heat treatment process to achieve the desired results. In addition, it is recommended to consult the material supplier or professionals before heat treatment for more accurate and detailed heat treatment recommendations.

Smelting and casting process of Grade 9 titanium alloy

The smelting and casting process of Grade 9 titanium alloy usually requires the following steps:

Raw material preparation: Prepare raw materials such as titanium, aluminum and vanadium that meet the alloy composition requirements.

Smelting: A vacuum consumable electrode arc furnace is used for smelting. This furnace is capable of heating and melting raw materials to high temperatures in a vacuum environment to ensure high-purity melts.

Refining: Refining the smelted alloy to remove impurities and bad components and improve the purity of the alloy.

Casting: Pour the smelted and refined alloy liquid into a pre-prepared casting mold. A variety of casting methods can be used, such as sand casting, continuous casting, vacuum casting, etc., and the appropriate casting process can be selected according to specific application requirements.

Cooling and solidification: After the alloy liquid cools in the mold, it forms a solid casting.

Post-processing: Perform deburring, heat treatment, machining and other subsequent processes on the casting to obtain the final product.

It should be noted that strict quality control must be maintained throughout the entire smelting and casting process to ensure that the composition and purity of the alloy meet requirements. In addition, relevant standards and specifications must be followed to ensure the safety and compliance of the production process.

Application overview and special requirements of Grade 9 titanium alloy

Grade 9 titanium alloy is widely used in high-tech military, aerospace and civil aircraft fields. It is mainly used in the manufacture of hydraulic, fuel and other piping systems. In the United States, Grade 9 alloy pipes have been widely used in various aircraft, including high-tech military aircraft, spacecraft and civilian aircraft. In China, the alloy is also used in the air-conditioning piping of transport aircraft and is planned to be used in the piping system of aerospace engines.

Grade 9 titanium alloy is suitable for manufacturing parts with operating temperatures below 315°C and requires certain strength, oxidation resistance and welding performance. Its strength is 20%-50% higher than that of pure titanium. It has good oxidation resistance and welding performance, and is suitable for manufacturing parts working in high temperature environments

Special requirements for Grade 9 titanium alloys may vary based on specific applications and industry standards. Generally speaking, it is necessary to comply with relevant aerospace standards and specifications to ensure that the chemical composition, mechanical properties, corrosion resistance, etc. of the alloy meet the requirements. In addition, for specific application scenarios, there may be special requirements, such as oxidation resistance at high temperatures, toughness at low temperatures, etc.

When using Grade 9 titanium alloy, appropriate materials and manufacturing processes should be selected based on specific application requirements and relevant standards, and necessary quality control and testing should be conducted to ensure that the performance and quality of the alloy meet the requirements.