1. Source of titanium metal

Titanium was discovered as early as 1791 by a British amateur mineralogist named Gregor. By 1795, the German chemist Klaplus named this unknown metal material after the Greek god Titans, which was translated into Chinese and English as "titanium". Titanium is abundant on the earth. There are more than 140 known titanium minerals, but industrial applications are mainly Ilmenite and Rutile. Among them, China's Ilmenite reserves account for 28% of the global reserves, ranking globally *.

Titanium is recognized as a non-toxic element in the world, with high mining and production costs and high prices. Due to a series of qualifications such as high and low temperature resistance, strong acid and alkali resistance, high strength, and low density, it has become a specialized material for NASA's same rocket and satellite, and has also been used in China's super projects such as the Yutu, J-20, and Shandong carrier. After entering the civilian field in the 1980s, it became the "Honorary Metal King" in the food industry due to its natural antibacterial and biological properties.

China's titanium industry started in the 1950s, and by the mid-1960s, China had built sponge titanium and titanium processing production plants in Zunyi and Baoji, respectively. This means that China has become one of the world's major titanium industry powers. In the 21st century, China's titanium industry has entered a new era of accelerated development, with titanium production capacity ranking among the top in the world.

2. Differences between pure titanium and titanium alloys

Pure titanium:

Or industrial pure titanium or commercial pure titanium, it is classified according to the content of impurity elements. It has excellent stamping process performance and welding performance, is not sensitive to heat treatment and microstructure type, and has a certain strength under satisfactory plastic conditions. Its strength mainly depends on the content of interstitial elements oxygen and nitrogen. The performance of 99.5% industrial pure titanium is: density P=4.5g/cm3, melting point 1800 ° C, thermal conductivity λ= 15.24W/(M.K), tensile strength σ B=539MPa, elongation: δ = 25%, reduction of area ψ= 25%, elastic modulus E=1.078 × 105MPa, hardness HB195.

Titanium alloy:

Titanium alloy is an alloy based on titanium and composed of other elements. It is a relatively young metal with a history of 60 to 70 years since its discovery. Titanium alloy materials have the characteristics of light weight, high strength, low elasticity, high temperature resistance and corrosion resistance, and are mainly used in components such as aviation engines, rockets, missiles, etc. Titanium has two types of isomorphic crystals; Titanium is a homoisomer with a melting point of 1720 ° C and a dense hexagonal lattice structure below 882 ° C, known as a titanium; At temperatures above 882 ° C, it exhibits a body centered cubic lattice structure, known as B titanium. By utilizing the different characteristics of the above two structures of titanium, appropriate alloying elements are added to gradually change its phase transition temperature and phase content, resulting in titanium alloys with different structures.

Titanium alloy elements can be divided into three categories based on their impact on phase transition temperature: ① stable phase A, and the elements that increase phase transition temperature are stable elements such as aluminum, magnesium, oxygen, and nitrogen. Aluminum is the main alloying element in titanium alloy, which has a significant effect on improving the room temperature and high temperature strength of the alloy, reducing the specific gravity, and increasing the elastic modulus The element that stabilizes the B phase and reduces the phase transition temperature is the B stable element. It can also be divided into two types: isomorphic type and eutectoid type. The former includes molybdenum, niobium, vanadium, etc.; the latter includes chromium, manganese, copper, silicon, etc The elements that have little effect on the phase transition temperature are neutral elements, such as zirconium and tin.

Titanium and titanium alloy number and chemical composition table

Below is a detailed explanation of common brand names:

TA1 (American Standard Gr1)

TA1 (Gr1) titanium is one of the four industrial pure titanium grades. It is * soft, * stretchable among these grades. It has excellent formability, corrosion resistance, and high impact toughness. TA1 grade is a material for any application that requires easy formability, typically used as titanium plate and titanium pipe.

TA2 (American Gr2) level

Due to its diverse and widespread availability, TA2 grade titanium is known as the "backbone" of the commercial pure titanium industry. It has many similar qualities as TA1 grade titanium alloy, but slightly stronger. Both are equally corrosion-resistant. This brand has good weldability, strength, ductility, and formability. This has made TA2 grade titanium rods and titanium plates popular in many application fields such as construction, power generation, and healthcare.

TA3 (American Gr3) level

This grade * uses less commercial pure titanium grade, but this does not reduce its value. The TA3 grade is stronger than the TA1 and TA2 grades, with similar ductility and only slight formability - but it has higher mechanical properties than its predecessors. TA3 grade is used in applications that require moderate strength and primary corrosion resistance, such as aerospace, chemical processing, marine industries, etc.

TA4 (American Gr4) level

The TA4 grade is considered the strongest among the four commercial pure titanium alloys. It is also known for its excellent corrosion resistance, good formability, and weldability. Used in applications that require high-definition technology such as body components, low-temperature vessels, and heat exchangers.

TA9 (American Gr7) level

TA9 level is mechanically and physically equivalent to TA2 level, except for the addition of interstitial element palladium to make it an alloy. Grade 7 has excellent weldability and characteristics, making it the most corrosion-resistant among all titanium alloys. In fact, it is resistant to corrosion in reducing acids. TA9 level is used for chemical processes and production equipment components. TA9 has extremely strong corrosion resistance, especially in reducing acidic environments.

TA9-1 (American Gr11) level

TA9-1 grade is very similar to TA1 grade, with the addition of a small amount of palladium to enhance corrosion resistance and make it an alloy. This corrosion resistance can be used to prevent Crevice corrosion and reduce acid in chloride environment. Other useful properties include ductility, cold formability, useful strength, impact toughness, and excellent weldability. This alloy can be used for titanium applications similar to Class 1, especially in areas where corrosion is required.

Ti 6Al-4V (National Standard TC4, American Standard Gr5) Grade

The "main force" of titanium alloys is Ti 6Al-4V or grade 5 titanium, which is commonly used among all titanium alloys. It accounts for 50% of the total amount of titanium used worldwide. Its usability lies in its many benefits. Ti 6Al-4V can be heat treated to increase its strength. It can be used for welding structures at temperatures up to 600 ° F. This alloy has high strength with light weight, useful formability, and high corrosion resistance. The availability of Ti 6AI-4V makes it a * alloy used in many industries, such as aerospace, medical, shipping and chemical processing industries. It can be used to create the following technical content:

• Aircraft Turbines

• Engine components

• Aircraft structural components

Aerospace fasteners

High performance automatic parts

• Marine applications

• Sports equipment

Ti 6AL-4V ELI (National Standard TC4ELI, American Standard Gr23) level

Ti 6AL-4V ELI or TC4ELI grade is a higher purity form of Ti 6Al-4V. It can be made into coils, twisted wires, wires, or flat wires. For any situation that requires high strength, lightweight, good corrosion resistance, and high toughness, it is *. It has excellent Damage tolerance for other alloys. These advantages make TC4ELI grade a dental and medical titanium grade. Due to its biocompatibility, good fatigue strength, and low modulus, it can be used in biomedical applications, such as implantable components. It can also be used for detailed surgical procedures, such as:

• Correction pins and screws

Orthopedic cables

• Ligature editing

Surgical implantation

• Orthodontic appliances

• In Joint replacement

• Low temperature containers

• Bone fixation device

TA10 (American Gr12) level

TA10 grade titanium has an "excellent" grade due to its high-quality weldability. It is a highly durable alloy that can provide great strength at high temperatures. TA10 grade titanium has similar characteristics to 300 series stainless steel. This alloy can be hot or cold formed using compression molding, hydraulic molding, tensile molding, or drop hammer method. Its ability to form in various ways makes it useful in many applications. The high corrosion resistance of this alloy also makes it invaluable for manufacturing equipment that needs to consider Crevice corrosion. The TA10 level can be used in the following industries and applications:

• Shell and heat exchanger

• Hydrometallurgical applications

High temperature chemical manufacturing

• Sea freight and air ticket components

Ti 5Al-2.5Sn

Ti 5Al-2.5Sn is a non heat-treatable alloy that can achieve good weldability and stability. It also has high temperature stability, high strength, good corrosion resistance, and good creep resistance. Creep refers to the phenomenon of plastic strain occurring for a long time at high temperatures. Ti 5Al-2.5Sn is mainly used for aircraft and fuselage applications as well as low-temperature applications.

*Attached are foreign and national standards for comparison of new and old titanium grades and chemical composition

3. Application of titanium and titanium alloys

Although titanium and titanium alloy materials have abundant reserves, their prices are very expensive. This is because titanium has low chemical activity under high temperature conditions, and its smelting technology and operating environment are very strict. It must be smelted under high temperature and vacuum conditions, often reaching temperatures above 800 ℃, which is much more difficult compared to steel and iron smelting. Therefore, when it comes to titanium alloy, people often think that it is a metal material with low production, high price, and few applications.

At present, due to the excellent properties of titanium alloy such as light weight, high strength, and high temperature resistance, titanium and titanium alloy materials are widely used in the manufacturing of weapons and national heavy weapons in various countries, especially suitable for application in the aerospace field. Examples of application areas are as follows:

Chemical industry

1. Alkali industry

The emergence of titanium refrigerators in the alkali industry can effectively solve the problem of substandard chlorine gas production due to the unreasonable traditional cooling process. At the same time, it has changed the production landscape of the chlor alkali industry, and the service life of titanium alloy refrigerators invested can reach up to 20 years.

2. Salt industry

At present, the more advanced salt production process is vacuum salt production, and the high-temperature concentrated brine generated during this process can cause serious damage to the carbon steel structure, resulting in equipment leakage. The use of titanium steel composite structure in the heating and evaporation chambers can effectively prevent salt scaling, improve salt production quality, and reduce the corrosion of high concentration salt water on the pipe wall during the evaporation process, extending the maintenance cycle.

Aerospace field

1. Aviation Industry

The application of titanium alloy in aviation is divided into aircraft structural titanium alloy and engine structural titanium alloy. The main application areas of aircraft titanium alloy structural components include landing gear components, frames, beams, fuselage skins, heat shields, etc. The Il-76 aircraft in Russia uses high-strength BT22 titanium alloy to manufacture key components such as landing gear and load-bearing beams; The transmission beam of Boeing 747 main landing gear is made of Ti-6Al-4V, and the forging is 6.20 meters long, 0.95 meters wide, and 1545 kilograms in weight; High strength and toughness Ti-62222S titanium alloy is used in key parts of the horizontal stabilizer shaft of C-17 aircraft. In terms of aviation engines, titanium alloys are used in compressor discs, blades, drums, high-pressure compressor rotors, compressor casings, etc. The leading edge and tip of the fan blade of the Boeing 747-8GENX engine are equipped with titanium alloy protective sleeves, which have only been replaced three times in the 10-year service life.

2. Aerospace industry

The working conditions of aerospace vehicles are extremely extreme. In addition to the need for advanced technology in material structure design, the excellent properties and functions of the materials themselves are also important, so titanium alloys stand out among many materials. In terms of aerospace equipment, in the 1960s, the wing beams and ribs of the twin cabin and the airtight cabin of the U.S. Apollo program were made of Ti-5Al-2.5Sn, and the lining was made of pure titanium; MT Aerospace Company of Germany has prepared a high-strength Ti-15V-3Cr alloy propulsion system storage tank and applied it to the European Alpha communication satellite giant platform; There are many examples of the application of Russian titanium alloys in aerospace engineering, such as the use of 3.5t BT23 titanium alloy large die forgings and forgings in the energy carrier rocket. In addition, titanium alloys are also used in the fuel compartments of liquid fuel rocket engines, low-temperature liquid storage tanks, and liquid hydrogen transfer pump blades.

Similarly, with the rapid development of domestic aerospace projects, titanium alloys have also been widely used. From Vostok 1 satellite in 1970 to the present Shenzhou series spacecraft and Chang'e probe, titanium alloys have been used. In addition, the cryogenic TA7ELI titanium alloy cylinders developed in China for use in the liquid hydrogen environment have been used in the Long March series launch vehicles; Harbin Institute of Technology has made Lunar rover rims with TC4 titanium alloy; In addition, China also uses high-strength titanium alloys such as BT20 to manufacture components such as engine shells and nozzles for missiles.

Ship sector

Titanium and titanium alloys are widely used in nuclear submarines, deep submersibles, atomic energy Icebreaker, Hydrofoil, Hovercraft, mine sweepers, propeller propellers, whip antennas, seawater pipelines, condensers, heat exchangers, acoustic devices, and fire-fighting equipment. For example, the US deep-sea vehicle 'Haiya' is equipped with a titanium observation module and control module, with a diving depth of up to 6100m; Japan Tobon Titanium Corporation and Fujitsu Shipyard jointly built the "Marichi TianII" all titanium speedboat, which was very popular in the United States for a period of time; China's first independently designed and integrated manned Submersible, Jiaolong, also uses titanium alloy. Jiaolong's working range covers 99.8% of the world's marine areas.

4. Existing problems and prospects of titanium and titanium alloys

Although titanium and titanium alloys have made significant progress, existing problems have also been exposed, and the development of titanium alloys also faces significant challenges. Mainly reflected in the following three aspects:

1) In terms of yield.

Although China is a major country in the titanium industry, the quantity of high-quality products in production is not high, and there are few types of titanium products with special properties. Secondly, China is still unable to produce titanium strips and titanium extruded profiles in batches, which limits the development and utilization of titanium and titanium alloys in fields such as aerospace and ocean. It is still very difficult to further increase the amount of titanium used in aviation engines to around 50%.

2) Performance aspect

Due to the high chemical activity of titanium metal and its susceptibility to contamination by other elements, the processing and manufacturing processes of titanium alloys are very high. At the same time, high-performance products processed need to comprehensively consider their mechanical, physical, chemical, and process properties. Existing titanium alloys have a temperature above 600 ℃, and the sharp decline in creep resistance and high-temperature oxidation resistance is the two main obstacles limiting the expansion of titanium alloy applications.

3) Cost aspect

At present, various countries are striving to reduce the application cost of titanium alloys and have achieved many achievements. However, in terms of the current situation in China, the management and technical level have not yet reached the ideal level, and the domestic titanium alloy product prices are less competitive internationally, which is not conducive to further expansion of use.

At present, the main application areas of titanium alloys are still military industrial departments such as aviation and aerospace, and new application areas are being developed, such as in automobiles, trains, and high-speed railways