Summary of knowledge related to titanium metal

Titanium metal was first discovered in 1791 by a British amateur mineralogist named Gregor. In 1795, the German chemist Klaprus named this unknown metallic substance after the Greek god Titans. The Chinese-English translation is "titanium". Titanium is abundant on earth. There are more than 140 known titanium minerals, but the main industrial applications are ilmenite and rutile. Among them, China's ilmenite reserves account for 28% of global reserves, ranking first in the world.

Titanium is a non-toxic element recognized around the world, but its mining and production costs are high and expensive. Because it has 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 special material for NASA rockets and satellite models. It has also been used in my country's Yutu, J-20, Shandong aircraft carrier and other super projects. After entering the civilian field in the 1980s, it became the "honorary metal king" in the food industry because of its natural antibacterial and biophilic properties.
my country's titanium industry started in the 1950s. By the mid-1960s, my country had built titanium sponge and titanium processing and production plants in Zunyi and Baoji respectively, which means that my country has become one of the world's titanium industry powers. Entering the 21st century, my country's titanium industry has entered a new period of accelerated development, with titanium production capacity ranking among the top in the world.

Pure titanium
Also known as industrial pure titanium or commercial pure titanium, it is graded according to the content of impurity elements. It has excellent stamping process performance and welding performance, is not sensitive to heat treatment and structure type, and has a certain strength under satisfactory plasticity conditions. Its strength mainly depends on the content of interstitial elements oxygen and nitrogen. The properties of 99.5% industrial pure titanium are: density P=4.5g/cm3, melting point 1800℃, thermal conductivity λ=15.24W/(M.K), tensile strength σb=539MPa, elongation: δ=25%, area shrinkage The rate ψ=25%, the elastic modulus E=1.078×105MPa, and the hardness HB195.
Titanium alloy
Titanium alloy is an alloy based on titanium and added with other elements. It is a relatively young metal, only sixty or seventy years old since its discovery. Titanium alloy materials have the characteristics of light weight, high strength, low elasticity, high temperature resistance and corrosion resistance. They are mainly used in aerospace engines, rockets, missiles and other components. Titanium has two isomorphic crystals. Titanium is an isomer with a melting point of 1720°C. It has a close-packed hexagonal lattice structure below 882°C and is called titanium; it has a body-centered structure above 882°C. The cubic lattice structure, called beta titanium, takes advantage of the different characteristics of the above two structures of titanium, adds appropriate alloying elements, and gradually changes its phase transformation temperature and phase content to obtain titanium alloys (titanium alloys) with different structures.
Titanium alloy elements can be divided into three categories according to their influence on the phase transition temperature: ① Elements that stabilize the α phase and increase the phase transition temperature are stable elements, such as aluminum, magnesium, oxygen, nitrogen, etc. Among them, aluminum is the main alloying element of titanium alloy. It has obvious effects on improving the normal and high temperature strength of the alloy, reducing the specific gravity and increasing the elasticity. ②Elements that stabilize the β phase and lower the phase transition temperature are β-stabilizing elements. It can be divided into two types: isomorphous and eutectoid. The former includes molybdenum, niobium, vanadium, etc.; the latter includes chromium, manganese, copper, silicon, etc. ③ Elements that have little effect on the phase transition temperature are neutral elements, including zirconium, tin, etc.

TA1 (American standard Gr1)
Gr1 titanium is the first of four grades of industrially pure titanium. It is the softest and most malleable of these grades. It offers maximum formability, excellent corrosion resistance and high impact toughness. Grade 1 is the material of choice for any application that requires ease of forming, and is commonly used as titanium plate and titanium tube.
TA2 (American standard Gr2) grade
Grade 2 titanium is known as the "workhorse" of the commercial pure titanium industry due to its versatility and wide availability. It has many of the same qualities as grade 1 titanium, but is slightly stronger. Both have equal corrosion resistance. This grade has good weldability, strength, ductility and formability. This makes Grade 2 titanium rods and plates the first choice for many applications including the construction, power generation and medical industries.
TA3 (American standard Gr3) grade
This grade uses at least a commercially pure titanium grade, but that doesn't make it any less valuable. Gr3 grade is stronger than Gr1 and Gr2 grades and has similar ductility but only slight formability. But it has higher mechanical properties than its predecessor. Grade Gr3 is used in applications requiring moderate strength and primary corrosion resistance, such as aerospace, chemical processing, marine industry, etc.
TA4 (American standard Gr4) grade
Grade Gr4 is considered the strongest of the four types of commercially pure titanium. It is also known for its excellent corrosion resistance, good formability and weldability. Used in some airframe components, cryogenic vessels, heat exchangers and other applications requiring high resolution.
TA9 (American standard Gr7) grade
Grade Gr7 is mechanically and physically identical to Grade 2 except that the interstitial element palladium has been added to make it an alloy. Grade 7 offers excellent weldability and performance and is the most corrosion resistant of all titanium alloys. In fact, it is the most corrosion-resistant of the reducing acids. Level 7 is used for chemical process and production equipment components. Gr7 is extremely corrosion-resistant, especially in reducing acidic environments.
TA9-1 (American standard Gr11) grade
Gr11 grade is very similar to Gr1 grade except that a small amount of palladium is added to enhance corrosion resistance, making it an alloy. This corrosion resistance can be used to prevent crevice corrosion and reduce acids in chloride environments. Other useful properties include optimal ductility, cold formability, useful strength, impact toughness and excellent weldability. This alloy can be used in the same applications as grade 1 titanium, especially where corrosion is required.
Ti 6Al-4V (national standard TC4, American standard Gr5) grade
Ti6Al-4V or grade 5 titanium is known as the "workhorse" of titanium alloys and is the most commonly used of all titanium alloys. Accounting for 50% of the world's total titanium consumption. Its usability lies in its many benefits. Ti6Al-4V can be heat treated to increase its strength. It can be used on welded structures with operating temperatures up to 600°F. The alloy combines high strength, light weight, good formability and high corrosion resistance. The availability of Ti6AI-4V makes it the best alloy for several industries including aerospace, medical, marine and chemical processing industries. It can be used to create technical content such as:

aircraft turbine
engine parts
aircraft structural parts
Aerospace fasteners
High performance automation parts
Marine applications
Sports Equipment
Ti 6AL-4V ELI (national standard TC4ELI, American standard Gr23) level
Ti 6AL-4V ELI or Gr23 grade is a higher purity form of Ti 6Al-4V. It can be made into coils, strands, wire or flat wire. It is the first choice for any occasion requiring high strength, light weight, good corrosion resistance and high toughness. It has excellent damage tolerance to other alloys. These advantages make Gr23 grade the ultimate 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:
Orthopedic cable
Orthopedic pins and screws
ligation
in joint replacement surgery
cryogenic container
Orthodontic appliances
surgical implants
bone fixation device
TA10 (American standard Gr12) grade
Gr12 grade titanium alloys receive an "Excellent" rating due to their high quality weldability. It is a highly durable alloy that provides great strength at high temperatures. Gr12 grade titanium has similar properties to 300 series stainless steel. The alloy can be hot or cold formed using press forming, hydroforming, stretch forming or the drop weight method. Its ability to be formed in a variety of ways makes it useful in many applications. The alloy's high corrosion resistance also makes it invaluable for manufacturing equipment where crevice corrosion is a concern. Grade Gr12 can be used in the following industries and applications:
Housing and heat exchanger
Hydrometallurgical applications
High temperature chemical manufacturing
Marine and aviation components
Titanium 5Al-2.5Sn
Ti 5Al-2.5Sn is a non-heat treatable alloy that allows for good weldability and stability. It also has high temperature stability, high strength, good corrosion resistance and good creep resistance. Creep is a plastic strain phenomenon that occurs at high temperatures for a long time. Ti 5Al-2.5Sn is mainly used in aircraft and airframe applications as well as cryogenic applications.

Although titanium and titanium alloy materials are abundant in reserves, they are very expensive. This is because titanium has very little chemical activity under high temperature conditions, and its smelting technology and operating environment are very harsh. It must be smelted under high temperature and vacuum conditions, and the temperature often reaches above 800°C, which is much more difficult to smelt than steel. Therefore, when it comes to titanium alloy, people think that it is a high-end metal material with low output, high price and few applications.
At present, due to the excellent properties of titanium alloys such as light weight, high strength, and high temperature resistance, titanium and titanium alloy materials are widely used in the manufacture of cutting-edge weapons and national weapons in various countries, and are especially suitable for use in the aerospace field. Examples of application areas include:

chemical industry
⑴Soda ash industry
The emergence of titanium refrigerators in the alkali production industry can effectively solve the problem of unqualified chlorine gas caused by unreasonable traditional cooling processes. At the same time, it has changed the production face of the chlor-alkali industry. The service life of the titanium alloy refrigerator invested can be as long as 20 years.
⑵ Salt industry
Currently, the more advanced salt production process is vacuum salt production. The high-temperature concentrated brine produced by this process will cause serious damage to the carbon steel structure and cause equipment to drip. The heating chamber and evaporation chamber adopt a titanium steel composite structure, which can effectively prevent salt scale and improve the quality of salt production. At the same time, it can reduce the corrosion of high-concentration salt water on the pipe wall during the evaporation process and extend the maintenance cycle.
Aerospace field
⑴Aviation industry
The application of titanium alloys in aviation is divided into titanium alloys for aircraft structures and titanium alloys for engine structures. The main application parts of aircraft titanium alloy structural parts include landing gear parts, frames, beams, fuselage skins, heat shields, etc. The Russian IL-76 aircraft uses high-strength BT22 titanium alloy to manufacture key components such as landing gear and load - load-bearing beam; the Boeing 747 main landing gear transmission beam material is Ti-6Al-4V. The forging is 6.20 meters long, 0.95 meters wide, and has a mass of 1,545 kilograms; the key parts of the horizontal stabilizer shaft of the C-17 aircraft are made of high-strength and high-toughness Ti-62222S titanium alloy. In aerospace engines, titanium alloys are used in compressor disks, blades, drums, high-pressure compressor rotors, compressor casings, etc. The leading edges and tips of the Boeing 747-8GENX engine fan blades use titanium alloy protective sheaths, which can only be replaced three times within a 10-year service life.
⑵Aerospace industry
The working conditions of aerospace vehicles are very extreme. In addition to the superb technology required for the structural design of materials, the excellent performance and functions of the materials themselves are also important. Therefore, titanium alloys stand out among many materials. In terms of aerospace equipment, in the 1960s, the double cabin and airtight cabin wing spars and ribs of the US Apollo program were made of Ti-5Al-2.5Sn, and the inner lining was made of pure titanium; prepared by the German MT Aerospace Company The high-strength Ti-15V-3Cr alloy propulsion system fuel tank is used on the European Alpha communications satellite giant platform; Russian titanium alloys have many applications in aerospace engineering. For example, the energy launch vehicle uses BT23 titanium alloy large die forgings weighing 3.5t and Forgings. In addition, titanium alloys are also used in fuel tanks of liquid fuel rocket engines, cryogenic liquid storage tanks, liquid hydrogen transfer pump impellers, etc.
Similarly, in the rapid development of domestic aerospace engineering, titanium alloys have also been widely used. From the Vostok-1 satellite in 1970 to the current Shenzhou series spacecraft, Chang'e probe, etc., titanium alloys have been used. In addition, titanium alloys are used in liquid hydrogen environments developed in our country. Low-temperature Ti-5Al-2.5Sn ELI titanium alloy gas cylinders have been used in the Long March series of launch vehicles; Harbin Institute of Technology uses Gr5 titanium alloy to prepare lunar rover rims; In addition, my country also uses high-strength titanium alloys such as BT20 to manufacture missile engine casings and nozzles Pipes and other components.
Ship field
Titanium and titanium alloys are widely used in nuclear submarines, deep submersibles, atomic icebreakers, hydrofoils, hovercrafts, minesweepers, propellers, whip antennas, seawater pipelines, condensers, heat exchangers, acoustic devices, fire-fighting equipment, etc. Predominant. For example, the American deep submersible "Haiya" is equipped with a titanium alloy observation cabin and control cabin, with a diving depth of up to 6100m; the all-titanium "Morris Sky 2" speedboat jointly built by Japan's Toho Titanium Company and Fuji New Shipbuilding It has been very popular in the United States for some time; my country's first self-designed and self-integrated manned submersible, the "Jiaolong", also used titanium alloy. The operation scope of "Jiaolong" covers 99.8% of the world's sea area.

Although titanium and titanium alloys have made significant progress, existing problems have also been exposed, and the development of titanium alloys also faces considerable challenges. Mainly reflected in the following three aspects:
1) From the perspective of output
Although our country is a big country in the titanium industry, it does not produce many high-quality products and has fewer types of titanium products with special properties. Secondly, my country is still unable to stably mass-produce titanium strips and titanium extruded profiles, which limits the use of titanium and titanium alloys in the aerospace field. , development and utilization in marine and other fields. It is still very difficult to further increase the titanium consumption of aeroengines to about 50%.
2) Performance
Because titanium metal is highly chemically active and easily contaminated by other elements, the processing and manufacturing technology of titanium alloys is very demanding. At the same time, the processed high-performance products need to comprehensively consider their mechanical, physical, chemical and process properties. When existing titanium alloys are above 600°C, their creep resistance and high-temperature oxidation resistance drop sharply, which are two major obstacles that limit the expanded application of titanium alloys.
3) Cost aspect
At present, various countries are working hard to reduce the application cost of titanium alloys and have achieved many results. But judging from the current situation in our country, our country's management and technical level have not yet reached the ideal level. The prices of domestic titanium alloy products are relatively competitive internationally. Poor and not conducive to further expansion of use.
At present, the main application areas of titanium alloys are aerospace and other military fields. The development of new application fields, such as automobiles, trains, high-speed rail and civilian fields commonly used in daily life, still has broad application prospects. In addition, replacing expensive alloy elements with lower-priced elements and reducing the cost of titanium alloy parts through technical means are important topics in future titanium alloy research work. After low-cost manufacturing of titanium alloys for high-end applications is achieved in the future, titanium alloys will be used in various fields.