Properties Of Cast Titanium Alloys And Their Applications in The Valve Industry
Aug 13, 2025
Compared to conventional alloy materials, titanium alloys offer numerous advantages, including low density, high specific strength, corrosion resistance, and excellent high and low temperature performance. Therefore, they are finding widespread application in a wide range of fields, including the petrochemical industry, marine environments, biomedicine, aerospace, automotive industry, and shipbuilding. Cast titanium alloys are obtained by casting titanium alloys into desired shapes. The most widely used alloy is ZTC4 (Ti-6Al-4V), which offers stable processing performance, excellent strength, and fracture toughness (below 350°C).
As key control components in pipeline transportation systems for various special environments and specialized fluid media, valves have become a vital component of many production equipment and are indispensable to virtually every industry. Due to the varying environmental, temperature, and media requirements across various industries, valve material selection is crucial and widely valued. Valves made primarily of titanium alloys and cast titanium alloys hold broad prospects in the valve industry due to their superior properties, including corrosion resistance, excellent high and low temperature performance, and high strength.
1. Commonly Used Cast Titanium Alloys
1.1 Types
With technological advancements and production needs, various cast titanium alloys have been developed and applied in a wide range of fields. Based on their photographic composition, cast titanium alloys can be divided into three types: α, β, and α+β. Based on their strength, they can be categorized into medium-strength and high-strength titanium alloys. Based on their operating temperature, they can be divided into low-temperature titanium alloys (room temperature or below), medium-temperature titanium alloys (400°C), high-temperature titanium alloys (500°C or higher), and flame-resistant titanium alloys. As can be seen, cast titanium alloys have a wide range of applications, covering almost every aspect and possessing high market value.
1.2 Mechanical Properties
Cast titanium alloys include ZTA1, ZTA2, ZTA5, and ZTC4, encompassing the α, β, and α+β types, designated domestically as TA, TC, and TB, respectively.
Taking the most widely used ZTC4 cast titanium alloy as an example, its Al content is 5.5% to 6.75%, its V content is 3.5% to 4.5%, and the remainder is Ti. As shown in Table 1, ZTC4 cast titanium alloy has a tensile strength of 895 MPa and a yield strength of 825 MPa. Its mechanical properties are comparable to those of medium- and high-strength steel, making it a suitable alternative to steel. Furthermore, its density, at only 4.4 g/cm³, is much lower than that of steel, facilitating weight reduction. At the same time, it retains the superior corrosion resistance of titanium alloy, a characteristic that steel lacks.
Therefore, in future industrial production, if weight reduction is required due to production needs, choosing a suitable cast titanium alloy as a replacement is an excellent option. This can effectively reduce product weight while maintaining performance, making it a good choice.
2. Applications of Cast Titanium Alloys in the Valve Industry
2.1 Marine Titanium Valves
In recent years, with the rapid development of my country's economy, various industries have flourished. As an essential general-purpose mechanical equipment, valves have seen increasing market demand, and my country's valve industry has also experienced rapid development. A valve typically consists of a body, bonnet, disc, stem, heat exchanger, packing, and actuator. The body and bonnet are considered the primary material, while the disc (gate), ball, seat, stem, and seal are considered the internal materials. Fasteners are also considered. Common valve materials include gray cast iron, ductile iron, alloy steel, and copper alloy, offering a wide range of options. However, as production demands increase, researchers have discovered that conventional valve materials are insufficient for production and research in some harsh operating environments and complex, specialized working conditions. Consequently, titanium and cast titanium alloys have attracted attention due to their superior performance, leading to the development of titanium valves.
Seawater pipeline systems operate in extremely harsh environments, and the performance of marine valves directly impacts the safety and overall performance of the pipeline system. As early as the 1960s, Russia began research on titanium alloys for shipbuilding, subsequently developing marine-grade beta-titanium alloys. These alloys were subsequently used in military vessel piping systems. These included globe, check, and ball valves, a wide variety of valves used in large quantities. Simultaneously, titanium valves also began to be used in civilian vessel piping systems. Subsequent launch tests demonstrated that the use of cast titanium alloys offered superior reliability in terms of structural strength and corrosion resistance compared to previously used copper alloys and steel. This significantly extended service life, from 2-5 years to more than double, garnering widespread attention. The triple-eccentric butterfly valves supplied by the China Shipbuilding Industry Corporation (CSIC) 725 Research Institute in Luoyang, my country, for a certain type of ship, embody a shift in material selection and design, employing materials such as Ti80. This extended the valve's service life to over 25 years, improving the reliability and practicality of valve applications and filling a technological gap in China.
2.2 Titanium Valves for Aerospace
Cast titanium alloys have also performed well in aerospace, thanks to their excellent heat resistance and strength. Also during the 1960s, American Airlines first experimented with titanium castings. After a period of research, cast titanium alloys began to be officially used in aircraft (such as the Boeing 757, 767, and 777) in 1972. Titanium alloy castings were not only widely used in stationary structures, but also in critical locations, such as valve controls in critical piping systems. Common valves include safety valves and check valves, reducing aircraft manufacturing costs and increasing safety and reliability. Furthermore, because titanium alloys have a lower density than other alloys, weighing only about 60% of steel of equivalent strength, their widespread use is driving steady progress towards higher-strength and lighter-weight aircraft.
Currently, aerospace valves are primarily used in various control systems, including pneumatic, hydraulic, fuel, and lubrication systems. They are particularly well-suited to corrosion resistance and high-temperature environments, making them crucial components for aerospace vehicles and engines. Traditional valves frequently require periodic replacement and may even be unable to meet demand. Furthermore, with the rapidly expanding aerospace valve market, titanium valves are increasingly gaining market share due to their superior performance.
2.3 Titanium Valves for the Chemical Industry
Chemical valves are generally used in harsh environments characterized by high temperature, high pressure, corrosion resistance, and large pressure differentials. Therefore, the appropriate material selection is crucial for valve applications in the chemical industry. Early materials, such as carbon steel and stainless steel, were often used. These materials rusted over time, necessitating replacement and maintenance. With the continuous development of titanium alloy casting technology and the gradual recognition of its superior performance, titanium valves have also come to the fore.
Taking the purified terephthalic acid (PTA) production unit of the chemical fiber industry as an example, the working medium is mainly acetic acid and hydrobromic acid, which are highly corrosive. Nearly 8,000 valves including stop valves, ball valves, etc. need to be used, with various types and huge quantities. Therefore, titanium valves become a good choice, which increases the reliability and safety of use. Generally speaking, due to the corrosiveness of urea, the valves at the outlet and inlet of the urea synthesis tower can meet the service life of 1 year and meet the use requirements. However, enterprises such as Shanxi Luliang Fertilizer Plant, Shandong Tengzhou Fertilizer Plant and Henan Lingbao Fertilizer Plant have made many attempts and finally selected titanium valves such as high-pressure check valves H72WA-220ROO-50, H43WA-220ROO-50, 65, 80 and insulated stop valves BJ45WA-25R-100, 125 for the inlet of the urea synthesis tower. The service life is more than 2 years, which reflects good corrosion resistance [9] and reduces the replacement frequency and use cost of valves.
The application of cast titanium alloys in the valve market is not limited to the aforementioned industries; it is also experiencing significant growth in other areas. For example, the new cast titanium alloy Ti-33.5Al-1Nb-0.5Cr-0.5Si, developed in Japan, boasts numerous advantages, including low density, high creep strength, and excellent wear resistance. Its use in automotive engine exhaust valves can improve engine safety and extend service life.
3. Applications of Cast Titanium Alloys in Other Industries
Compared to the application of cast titanium alloys in the valve industry, cast titanium alloys have a wider range of applications. Titanium and its alloys both possess excellent corrosion resistance, making them crucial for industries with corrosive requirements, such as the petrochemical industry. Within these industries, large-scale industrial equipment such as positive displacement pumps, heat exchangers, compressors, and reactors often utilize corrosion-resistant titanium castings, representing the largest market demand. In the medical field, titanium is recognized worldwide as a safe, non-toxic metal with no heavy metal release. Therefore, many medical assistive devices and prosthetic limbs are made of cast titanium alloys.
This is particularly true in dentistry, where nearly all tested dental castings are made of commercially pure titanium and Ti-6Al-4V alloy, demonstrating excellent biocompatibility, mechanical properties, and corrosion resistance. Furthermore, due to their low density and excellent performance, titanium and its alloys are widely used in a variety of sporting equipment, including golf clubs, club heads, tennis rackets, badminton rackets, and fishing tackle. Products made from titanium are lightweight, have a guaranteed quality, and are very popular among the public. For example, the SP-700 titanium alloy developed by Nippon Kogan Co., Ltd. (N104) is used as the surface material for Taylor 300 series golf heads and is a global hit.
Since the late 20th century, the use of cast titanium alloys in fields such as petrochemicals, aerospace, biomedicine, the automotive industry, and sports and leisure has progressed from initial exploration to widespread promotion and development, gradually achieving industrialization and scale.
Titanium and its alloys offer superior performance, making them ideal substitutes for many materials, such as steel. Furthermore, titanium resources are abundant, attracting the attention of numerous researchers. While challenges remain, such as the difficulty of mining and smelting titanium resources and processing, the valve and titanium industries are both vibrant and rapidly developing. With the future stability of titanium mining and production, and the introduction and refinement of new processes, the application of cast titanium alloys and castings in the valve industry will mature and become more widespread, with broad application prospects in other industries as well.
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