Application analysis of titanium and titanium alloy materials
With the rapid development of aerospace, automotive lightweight, biomedical materials and other industries, the research and application of titanium alloy materials has become one of the hot spots in the field of materials. The density of titanium alloy is generally about 4.51g/cm3, only 60% of that of steel, but the mechanical strength of titanium is similar to that of steel, and even some newly developed titanium alloy has exceeded the strength of some high-strength structural steel. Therefore, compared with other commonly used structural materials such as steel and aluminum, the specific strength of titanium alloy shows obvious advantages; the thermal strength of titanium alloy is high, which can be at 450-500 ℃ Long term operation under temperature; good corrosion resistance, especially for pitting corrosion, acid corrosion and stress corrosion, which can work in humid atmosphere and sea water medium, and its corrosion resistance is far better than that of stainless steel; in addition, it also has excellent corrosion resistance for alkali, chloride, nitric acid, sulfuric acid, etc. At the same time, the mechanical properties of titanium alloy can be maintained at low and ultra-low temperature. For example, at – 253 ℃, TA7 still has good plasticity. Therefore, titanium alloy can also be used as low temperature structural materials.
However, it is difficult to process titanium alloy. In the process of smelting and casting of titanium alloy, titanium is easy to react with impurities such as hydrogen, oxygen, nitrogen, carbon and so on, which makes the process quality difficult to guarantee; in addition, its poor wear resistance and machining difficulties cause its high manufacturing cost, and its application is limited to some extent. Although its content in the crust is very rich, 0.63%, next to oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, hydrogen, ranking 10th in the sequence of element distribution, the development of titanium alloy is relatively backward compared with steel, aluminum, etc. As early as 1791, titanium was found in ores such as rutile (TiO2) and ilmenite (FeTiO3). However, how to extract titanium from these ores has puzzled people for more than 100 years. It was not until 1910 that pure titanium was produced for the first time, which opened the application era of titanium materials.
China’s titanium reserves rank first in the world, accounting for about 46% of the world’s total titanium . With the progress of science and technology, China has formed an industrial chain from titanium ore to titanium ingot to titanium alloy processing. At present, titanium and its alloys have been widely used. The titanium industry develops at an average annual growth rate of about 8%. The application fields of titanium alloy are more and more extensive from aerospace, spaceship, deep sea and oil well.
Industrial application of titanium and titanium alloy
Table of Contents
- 1 Industrial application of titanium and titanium alloy
- 2 Application of titanium and titanium alloy in civil life
- 3 Development trend and difficulties to overcome
- 4 Conclusion
Titanium alloy is an ideal aeronautical structural material because of its excellent properties such as low density and high specific strength. At present, the application of titanium alloy in aeronautical and astronautical industry is more and more popular.
In the 1950s, only a small number of non load-bearing components such as rear fuselage heat shield, wind guide cover and tail cover were made of titanium alloy; since the 1960s, the important load-bearing components such as partition frame, beam and flap slide rail in the middle fuselage have gradually replaced structural steel with titanium alloy. In terms of the current trend, the more advanced the new aircraft, the more wide body aircraft, the greater the titanium consumption. The density of C-5 titanium alloy which was put into service in the United States in 1970 was 6%, and then the density of C-17 increased to 10.3%. After 2006, the titanium consumption of the fourth generation fighter F22 in the United States was as high as 39% – 41%. China has also made great progress in the research and application of titanium alloys. The mass of titanium parts of J-7 aircraft which was put into production in 1960s is only 9kg, and that of J-8 Ⅱ aircraft which was produced in 1980s is 93kg. In 2002, the titanium consumption of the designed and finalized Kunlun turbojet engine was increased to 15%, and that of the first turbofan engine in China was increased to 25%.
Since the 1970s, a large number of titanium alloys have been used in civil aircraft. For example, a Boeing 787 has a titanium consumption of up to 136t, accounting for 15% of the total aircraft mass. In addition, pressure vessels, fuel tanks, fasteners and rocket shells in the aerospace industry began to be made of titanium alloy.
Application in ship field
Titanium belongs to the element with more active chemical properties, and has great affinity with oxygen. When it is placed in the air, it reacts with oxygen to form a compact TiO2 protective film on its surface, which makes titanium alloy free from the corrosion of foreign media. Therefore, titanium alloy has good corrosion resistance, which can show good chemical stability in acid, alkali and oxidizing medium. Its corrosion resistance is better than existing stainless steel and most non-ferrous metals, and even can be compared with platinum. The hardness of pure titanium is about hv150, which is not very high, but the hardness increases obviously after adding alloy elements. For example, the surface hardness of TA4 is about hrc30, which is higher than that of conventional stainless steel and common carbon steel. If the surface is treated, it can exceed HRC60. Under low temperature and ultra-low temperature conditions, titanium still maintains its original performance, and the strength and hardness are maintained in high water Flat, so titanium alloy is very suitable for making ship parts. For example, the submarine mainly made of titanium alloy can withstand a depth of 4500m without damage, while the index of general steel submarine is about 300m.
Since the 1960s, many countries have begun to study the application of titanium alloy to ship industry, such as the United States, Russia, Japan, China, Britain, France and Germany.
Titanium alloy has unique physical properties (including magnetic properties), high specific strength, impact resistance, excellent corrosion resistance and erosion corrosion resistance, which make it widely used in ships, especially in the United States, Russia and other military powers. The research of titanium alloy is obviously ahead of the world. For example, Russia is the first country in the world to develop and use titanium alloy for ships. At present, it has built a systematic series of titanium alloy for ships, developed different series of titanium alloy products with different strength levels, and has been successfully applied to ship hull, ship machinery, power plant and other ship parts and corresponding equipment. The production process of titanium and titanium alloy products has been relatively mature. The United States has developed a series of titanium alloy products There are also many researches on titanium alloy for ships, which is improved on the basis of titanium alloy for aviation. High performance titanium alloy is used in the sea water cooling system, sea water system and fire extinguishing system, structural parts and thrusters of ships on different hulls such as nuclear powered aircraft carrier, missile cruiser and missile frigate.
Since the 1960s, China has strengthened the research on titanium alloy for ships. In recent decades, remarkable achievements have been made in the research and application of titanium alloy for ships. A complete series of titanium alloy for ships has been formed, which basically meets the requirements of navy ships, submarines and deep submersibles for titanium alloy with different strength. For example, low strength titanium alloy with yield strength less than 490 MPa has excellent plasticity, such as Ti31, which is used to manufacture heat exchanger, condenser, etc.; medium strength titanium alloy with yield strength between 490 and 790 MPa, such as ZTi60, which is used to manufacture various pressure system castings; higher than 790 MPA high-strength titanium alloy has also been used in the heat-resistant and corrosion-resistant parts of marine power engineering, such as propeller, high-pressure vessel, ejection device, etc.
In recent years, in order to further improve the equipment level of China’s navy, China attaches great importance to the research and development of new materials in the field of ships. The special properties of titanium alloy make it have a very broad application prospect in the field of ships.
Titanium has good corrosion resistance, and it is one of the important structural materials in the equipment used in the chemical industry. Using titanium alloy instead of stainless steel, nickel base alloy and other rare metals can effectively reduce operating costs and prolong the service life of equipment, which is of great significance in improving product quality, saving energy and reducing consumption.
In recent years, titanium alloy materials in China’s chemical industry are mainly used in distillation tower, reactor, pressure vessel, heat exchanger, filter, measuring instrument, turbine blade, pump, valve, pipeline, chlor alkali production electrode, synthetic tower lining and other acid resistant equipment lining.
(1) Application in chlor alkali industry
In chlor alkali industry, sodium hydroxide (NaOH) is prepared by electrolysis of saturated sodium chloride (NaCl) solution, and the process of further production of a series of chemical products, so the requirements for corrosion prevention are very high, so the application demand of titanium alloy materials in chlor alkali industry is very large. At present, in chlor alkali industry, titanium alloy materials have been used to prepare equipment such as wet chlorine cooler, anode electrolyzer, heating pipe of dechlorination tower, vacuum dechlorination pump, etc. For example, a large number of high temperature wet chlorine gas with temperature of 75-95 ℃ is produced in the process of caustic soda production by salt electrolysis, which seriously pollutes the environment. The wet chlorine gas cooler made of titanium alloy is used instead of graphite cooler, and good results are obtained. Some of them have a service life of more than 20 years.
(2) Titanium alloy materials are also widely used in Soda Industry
Soda ash is one of the most basic chemical raw materials. Its production process is mainly the synthetic alkali process, including ammonia alkali process and combined alkali process. No matter which process, ammonia (NH3) and carbon dioxide (CO2) are mostly used as gas medium, while the liquid medium is the solution with high concentration of chloride ion (Cl -). In the past, carbon steel and cast iron were mostly used in the main equipment such as carbonization tower tube, cooler and crystallizing external cooler. The reaction tower suffered serious corrosion and leakage. Great changes have taken place since titanium alloy was used. For example, the alkali plant of Dalian Chemical Industry Co., Ltd. purchased TA2 tube from Baoji Nonferrous Metal processing plant to replace the internal cast iron tube of ammonia condenser, which was put into operation for 14 years without any corrosion leakage and extended its service life.
Application of high-end oil well pipe
Since Edwin Drake drilled his first oil well in Titusville, Pennsylvania in 1859, the oil industry has developed rapidly. At present, oil and natural gas have replaced coal as the largest energy source used by human beings. Pipe material is the most consumed material in oil and gas drilling and production. It not only consumes a large amount of money, but also has a significant impact on the quality of the oil industry, directly affects the life of a single well of oil and gas wells, and then affects the overall efficiency of the oil industry.
With the development of modern drilling and production technology, China’s petroleum drilling began to develop to deeper and more demanding oil and gas wells. With the further development of production depth, the service environment of oil well pipe has expanded to the extremely harsh conditions of coexistence of high temperature and pressure, high CO2, hydrogen sulfide (H2S), Cl -, and other corrosive media.
Nickel base alloy is widely used as the raw material of traditional high-end corrosion-resistant oil well pipe. However, in recent two years, the limitation of nickel base alloy has gradually emerged, which is expensive and heavy. In some harsh environments, such as sulfur corrosion resistance, it can not resist. Titanium alloy is lighter and better in corrosion resistance. Tianjin steel pipe group, through a large number of experiments, takes titanium as the matrix, adds some alloy elements to ensure the corrosion resistance, while improving the strength and toughness. In addition, through improving the machining technology, designs special screw threads that conform to the characteristics of titanium alloy to ensure the tightness of oil pipe connection. The running depth of titanium alloy oil pipe developed and produced by the steel pipe group exceeds 6 300m, becoming the first company in the world to develop titanium alloy tubing and apply it to ultra deep and high sulfur oil and gas fields.
Application of titanium and titanium alloy in civil life
Titanium and titanium alloy are not only indispensable structural materials in aerospace industry, but also widely used in shipbuilding, chemical industry, petroleum exploitation and so on. At present, it is gradually developed and applied in biomedical, glasses, jewelry, mobile phones, computers and other civil industries, with a constant growth rate every year.
Titanium is an ideal medical metal material with good biocompatibility. As early as the mid-1980s, the United States began to develop biocompatible titanium alloy without aluminum, vanadium and other elements, which was used in orthopedics. At present, titanium alloy materials are mainly used to manufacture medical devices, prostheses or artificial organs implanted in human body and titanium alloy for auxiliary treatment equipment.
Since the 1970s, China has made remarkable achievements in the research of biomedical titanium and titanium alloy. At present, titanium alloy materials can be used to make medical devices, such as artificial hip joint, knee joint, shoulder joint, flank joint, skull, active heart valve, bone fixation clip, etc.
For example, titanium alloy porcelain teeth, with high strength and low price, are widely used in China. Titanium alloy porcelain teeth are beautiful in appearance and stable in color, which can well restore the shape and function of teeth, especially for people sensitive to nickel ion, and can avoid gum bleeding and black gum phenomenon. In addition, it has strong corrosion resistance and is not easy to turn black. The biocompatibility of this material is better than that of non precious metal porcelain teeth, and its service life can be up to 10 years.
Application in glasses industry
Titanium is becoming a new type of spectacle frame material. The spectacle frame made of titanium alloy has the advantages of high hardness, good flexibility, ergonomics, good elasticity, long-term use, no deformation, no fading, warm and smooth touch, no cold feeling of other metal spectacle frame, no toxicity to human body and no radiation. In addition, titanium and nickel can form “memory alloy”, that is, memory titanium alloy. After deformation of this spectacle frame, it can be restored to its original state by washing it with water at a specific temperature.
The production process of titanium frame is very demanding, not only has many processing procedures, but also needs special processing equipment, special welding technology and electroplating process, so the price of titanium frame is higher than other metal, plate or plastic frames. However, with the improvement of people’s living standards, the demand for titanium mirror frame is also growing. It needs the majority of scientific and technological workers to continuously research and develop various new technology, improve production and processing technology, and make it accepted by more and more people.
Application in jewelry industry
Compared with gold, platinum and other precious metals, titanium as a new jewelry material not only has an absolute advantage in price, but also in other aspects.
- ① Light, the density of titanium alloy is 27% of gold. It has obvious advantages in making earrings, necklaces and other jewelry. It can design and process some special jewelry with large volume and unique shape.
- ② Titanium has good corrosion resistance. The oxide film formed on the surface of titanium is extremely complete and dense. After local damage, it will repair itself instantly without affecting its appearance.
- ③ Good biocompatibility, people will not cause allergies after long-term contact, especially for people with metal allergies can wear it at ease.
- ④ Titanium can be colored by changing the thickness of the oxide film to change the color without additional elements. The colors available now include gold, black, blue, brown, flowers, etc. the colors are fashionable.
- ⑤ Titanium has high hardness and is not easy to deform. It does not need to be reshaped after wearing ordinary gold and silver jewelry for a period of time.
Development trend and difficulties to overcome
Titanium and its alloys have made remarkable progress, but due to their poor process performance, the cost of titanium refining and processing is quite high, which limits the development and application of its alloy system.
Processing technology to be improved
Due to the high chemical activity of titanium at high temperature, it is easy to be polluted by oxygen, nitrogen, carbon and other elements, so the requirements of titanium alloy processing and manufacturing process are very high. Therefore, the manufacturing cost of titanium alloy materials is very expensive, and its application field is limited. At present, most of them are used in aircraft structure, aircraft, petroleum and chemical industries and other high-tech industries.
Due to the poor rigidity and thermal conductivity of titanium alloy, the local high temperature results in knife sticking and so on. Generally, the machinability of titanium alloy is only 20% – 40% of that of 45 steel, the hardness is less than hb300, and the knife sticking is serious; HB > 370 is too hard to machine. In addition, titanium has high chemical activity and is easy to combine with gas impurities. When the temperature is over 600 ℃, titanium is oxidized into a brittle layer, which is called “tissue α layer”; hydrogen embrittlement occurs with hydrogen; hard and brittle titanium nitride (TIN) is formed with nitrogen at high temperature, which aggravates tool wear. In addition, titanium alloy can combine with the elements of cutting tool material, which results in serious adhesive wear.
How to further develop the purification and alloying process of titanium alloy, optimize the machining means, and further reduce the manufacturing cost of titanium alloy products is the key to promote the wide application of titanium alloy.
Research and development of high-end products with high added value
At present, titanium alloy processing enterprises also have low technology level, overcapacity and other phenomena. Therefore, enterprises need to increase innovation and produce high-end products with high added value to provide strong competition for enterprises. At the beginning of December 2016, the 20t ingot produced by Qinghai Juneng Titanium Co., Ltd. became the largest single ingot in the whole country and even in Asia. On this basis, a 500mm thick oversized ingot was successfully trial produced, which can be rolled into a 200mm strip slab, and then a wide plate with a width of more than 1.8m was directly rolled, thus overturning the traditional rolling process and filling the international technical gap. The technology greatly shortens the processing cycle, reduces the processing links, improves the yield, reduces the processing cost, and expands the competitive advantage of products.
The manufacturing process of titanium alloy and its products requires high requirements, as well as the production equipment and processing equipment, and the quality control of products also has certain difficulties, so the current application of titanium materials is still lack of standard industry standards. This means that the quality control of titanium alloy and its products can not meet the unified requirements, resulting in uneven product quality, which is extremely detrimental to the expansion of the application field of titanium alloy.
The development prospect of titanium alloy can be described as bright and open. Because of its excellent performance: high specific strength, low density, anti-corrosion and so on, it has been applied in many fields, such as aviation, military, ship, petrochemical and so on. In addition, because of the good compatibility between titanium alloy and human body, the medical field has obtained very rapid development.
The advantages of titanium alloy attract people’s attention, but its expensive price makes people have to be deterred and its application is limited. It is believed that with the improvement and improvement of titanium smelting technology and processing technology, the varieties and quality control level of titanium and titanium alloy products will be further expanded, and their application fields will also be expanded, especially in the civil industry, such as tableware, jewelry, mobile phones, computers, crutches and other civil leisure products, which can be realized as long as people have demand.
Source: China Titanium Alloy Flange Manufacurer: www.titaniuminfogroup.com