Properties and Applications of Titanium Plate and Titanium Alloy Plate

（1） Properties of titanium

The appearance of titanium is very similar to that of steel. Its density is 4.51g/cm3, less than 60% of steel. It is the lowest density metal element among refractory metals.

Titanium is very stable in air at room temperature. When heated to 400~550 ℃, a firm oxide film will be formed on the surface to prevent further oxidation. Titanium has a strong ability to absorb oxygen, nitrogen and hydrogen. This kind of gas is a very harmful impurity to titanium metal. Even if its content is very small (0.01%~0.005%), its mechanical properties can be seriously affected.

The mechanical properties of titanium, commonly known as mechanical properties, are closely related to purity. High purity titanium has excellent machinability, good elongation and reduction of area, but low strength, so it is not suitable for structural materials. Industrial pure titanium contains appropriate impurities, has high strength and plasticity, and is suitable for making structural materials

Among titanium compounds, titanium dioxide (TiO2) has the most practical value. Ti02 is inert and harmless to human body. It has a series of excellent optical properties. Ti02 is opaque, with high glossiness and whiteness, large refractive index and scattering power, strong hiding power and good dispersion. The pigment made of Ti02 is white powder, commonly known as titanium white, which is widely used.

（2） Application of titanium

1. Application of titanium and its alloys

Due to its light weight, higher strength than aluminum alloy, and its ability to maintain higher strength than aluminum at high temperatures, compact titanium is highly valued by the aviation industry. Since the density of titanium is 57% of steel, its specific strength (strength/weight ratio or strength/density ratio are both called specific strength) is high, and its corrosion resistance, oxidation resistance and fatigue resistance are strong. Three quarters of titanium alloys are used as structural materials represented by aircraft structural alloys, and one fourth are mainly used as corrosion resistant alloys.

Titanium alloys can be divided into low strength high plasticity, medium strength and high strength, which are 200 (low strength)~1300 (high strength) MPa. However, titanium alloys can generally be regarded as high strength alloys. They are stronger than the aluminum alloy which is considered as medium strength, and can completely replace some types of steel in strength. Compared with the rapid decrease of the strength of aluminum alloys at temperatures above 150 ℃, some titanium alloys can still maintain good strength at 600 ℃.

In addition to strength, it can also be divided into titanium alloys with heat resistance, corrosion resistance, low temperature and special functions (such as TiNi shape memory alloy, TiFe hydrogen storage alloy) according to the use, and can be divided into α、α＋β and β  And near α、 There are several types such as metastable. Up to now, more than 100 alloy grades have been put into production, and only 10 are widely used in industry. Among them, Ti-6Al-4V used as structural alloy accounts for 60% of the total sales market of titanium alloy, which is the leading position, followed by Ti-5Al-2.5Sn, whose long-term working temperature can reach 500 ℃ (strength is 780-980 MPa).

However, titanium has two main factors that make this resource rich element unable to become a common metal. The first is cost. According to the market price in the United States, the titanium ingot is 8-12 dollars per pound (1 pound=0.45 kg), the aluminum ingot is 1.00~1.30 dollars per pound, and the carbon steel is 0.20~0.40 dollars per pound. But the main factor is that titanium itself is very active and difficult to handle. The atmosphere in the furnace must be strictly controlled, and welding must be carried out in inert atmosphere. Titanium metal has high activity, low thermal conductivity, large deformation resistance, and poor plasticity at room temperature. It is not only easy to bond with the mold during deformation, but also tends to bond tools and abrasives to the hot machined surface during machining, which makes the manufacturing of standard structural parts produce a large number of titanium scraps, namely, residual titanium. Generally, 70% of the residual titanium can be produced during the processing of forged titanium ingots, sometimes as high as 90%.

In order to reduce the burden caused by excessive cost, on the one hand, the technology of titanium residue treatment has been developed; on the other hand, new and high technologies such as near net forming, superplastic forming, precision casting, powder metallurgy, hot isostatic pressing and diffusion bonding have been developed. For example, the powder metallurgy products processed by pulverizing, molding, sintering or hot isostatic pressing consolidation methods are near net shaped parts, and the material utilization rate is as high as 80%, which not only reduces the material consumption, but also significantly reduces the amount of cutting. Another example is the application of large thin wall precision casting technology in titanium alloy, which makes the performance of titanium castings close to that of titanium forgings and reduces the cost by about 50%.

The main consumption area of titanium and titanium alloys is the aviation industry. In the 1980s, the U.S. aviation industry used 74.8% of titanium materials. Russia and the United Kingdom were also mainly used in the aviation industry, while Japan used 90% of titanium materials for civil industry. In recent years, the application of titanium materials in non aerospace industry is increasing, and aerospace is still in the "leading" position. Since titanium was used as engine nacelle and firewall on Douglas DC-7 in 1952, many aircraft structures have been made of titanium alloy. Titanium parts play a crucial role in Boeing 757, supersonic SR-71 Blackbird, F-22 jet fighter, space satellite and missile. For example, fan discs and engine blades in aircraft are made of titanium castings and forgings.

The second application area of titanium is related to its corrosion resistance. The largest amount is used as electrode material for chlor alkali production. The service life of titanium anode is 10 times as long as that of graphite anode, which increases the productivity by nearly one time and saves 15% electricity. The annual output of caustic soda is 10000 tons, which requires about 5 tons of titanium.

In the shipbuilding of the maritime industry, titanium has had its past glory. The titanium consumption of each of the 6~7 3000 ton nuclear submarines manufactured by the former Soviet Union is up to 560 tons (the titanium consumption of the alpha class submarines is more than 908 tons). In recent years, titanium has shown great power in offshore oil and gas exploration and development. From 1997 to 1999 alone, Europe invested 15 billion dollars in oil and gas development in the North Sea to build 21 suspended production vessels and 64 platforms. The life safety system of a new platform needs 50-500 tons of titanium, the wedge stress joint needs 50-100 tons of titanium, the telescopic lifter needs 400-1200 tons of titanium, and the fixed lifter needs 1400-4200 tons of titanium.

In the energy industry, it is known that titanium is used as the condenser and heat exchanger of power generation devices. For example, the power generation units of Taizhou Power Plant, Shanghai Jinshan Thermal Power Plant and Zhenhai Power Plant all use titanium tube condensers, which use about 700 tons of titanium. Both Qinshan and Daya Bay Nuclear Power Plants have selected all titanium condensers. In recent years, in the field of geothermal well and geothermal development, titanium has also shown great charm and fully demonstrated its corrosion resistance. As a power steam turbine in the high-temperature corrosive environment of geothermal brine, other materials have to be replaced by titanium due to their short life. The advantage of using titanium is that it can improve the productivity of heat recovery and the life of geothermal wells. Since the 1990s, the United States has drilled a geothermal well with a temperature of up to 300 ℃ in Salton Sea, Southern California, and 227 tons of Ti-6Al-4V-0.1Ru alloy hot-rolled seamless tubes have been used. It is estimated that in the next ten years, the amount of titanium used for geothermal development around the world may reach 2400 tons. If titanium materials are used in Yangbajing Power Station in Tibet, its appearance will be greatly improved.

Ti-6Al-4VELI, Ti-3Al-2.5V, Ti-6Al-4V-0.1Ru, Ti-3Al-2.5V-0.1Ru and molybdenum bearing Ti-38644 (Ti-3Al-8V-6Cr-4Zr-4Mo) alloys are mainly used for offshore oil and gas drilling and geothermal development. Ti-5111 (Ti-5Al-1Sn-1Zr-1V-0.8Mo) alloy is used for marine fasteners. In order to meet the needs of ocean engineering, China has also developed Ti75, Ti31 and Ti631 alloys.

According to statistics, the titanium consumption of a 200000 kW thermal power generation unit is 90 tons, and that of a nuclear power plant is 80~100 tons. It can be seen that the amount of titanium used in energy and corrosion should not be ignored.

Golf, biomaterials and automobile manufacturing are three promising new application fields of titanium materials.

In the field of sports and leisure, the growth of golf equipment consumption is quite dramatic. In 1993, titanium did not enter this field. In 1997, the titanium consumption increased to 4000 tons. The reason is that using titanium as the bat has high strength, light texture, and the average hitting distance is increased by 20-30 yards (1 yard=0.9144 meters) or 15%. The appearance of titanium bat made the United States add 448 new courts in 1998. The number of players reached 25 million (nearly half of the world). In 1994, only 500 clubs were sold. In 1995, the number of clubs sold increased to 190000, but in 1997, the number jumped to 1.72 million. Titanium has great potential in the field of leisure sports, such as ski, sledge, ice axe, ice claw and other climbing facilities.

Titanium has excellent biocompatibility, low expansion coefficient, high durability and non magnetism, and is an excellent bone support material. The weight of the implanted hip joint is about half of that of the stainless steel, and the bone tissue can also be directly adhered to the titanium implant body when growing. Titanium alloy is also used for knee joint and denture reconstruction. According to statistics, the annual titanium consumption of medical implants in the world is 600-1000 tons. In addition to Ti-6Al-4VELI (ultra-low interstitial oxygen), titanium alloys such as Timetal 21SRx (Ti-2.75Nb-15.2Mo-0.34Fe-0.18Si-0.250), Timetal 21S (Ti-2.9Nb-14-9Mo-0.09Fe-2.9Al-0.22Si-0.140) and Ti-6Al-7Nb have also been developed for the titanium materials used.

With the development of low-cost titanium production and titanium powder processing technology, it is possible to extend the application of titanium to the automotive industry. The springs made of titanium have been used in Formula One racing cars, racing motorcycles and the most advanced Ferrari cars. It is estimated that it will soon be applied to engine valves, connecting rods, suspension springs, emission systems and fasteners of light vehicles. It is estimated that the large-scale entry of titanium into the automobile market will start from Japan and the United States. The United States can produce 16 million cars and light trucks every year. In the second half of 1998, Honda Company of Japan used titanium valves in Altezza family cars.

2. Application of titanium dioxide

Titanium white is mainly used in coatings, plastics, paper making, synthetic fibers, printing inks, rubber, enamel and other aspects, which is inferior to other white coatings. The titanium sol composed of superfine titanium dioxide, water and organic solvent has become an independent new variety, which is used in cosmetics, lens surface finishing agents, inks and paint additives, and its application fields are still expanding. The United States is the largest producer and consumer of titanium dioxide in the world. In 1998, the output was 1.36 million tons, the apparent consumption was 1.13 million tons, and the output value was up to 3 billion dollars. China's production and consumption are much smaller. The consumption of titanium dioxide in the United States is 50% for pigments, paints and varnishes, 23% for paper making, 23% for plastics and 9% for other purposes.

3. Other applications

The titanium iron (TiFe) made from ilmenite concentrate is a deoxidizer and stabilizer used in the manufacture of stainless steel. The titanium iron hydrogen storage anode has its own advantages and disadvantages compared with rare earth hydrogen storage materials in the manufacture of hydrogen storage batteries, but its cost is relatively low. It will compete with rare earth in hydrogen storage, transportation, catalysis, fuel cell, etc. Ti Ni shape memory alloy is an indispensable high-tech material for medical and military industries. As for electronic ceramic functional materials, barium titanate, strontium titanate, titanium compound catalyst and organic titanium and titanium are inert metals. Its chemical symbol is ti, atomic number is 22, and it is a silver metal. Specific gravity 4.51, melting point 1668 ℃ Its reserves in the earth's crust are very rich, ranking fourth only after iron, aluminum and magnesium, and more than ten times more than the sum of commonly used metals copper, nickel, lead and zinc. The ores used to produce titanium in industry include rutile, ilmenite and titanomagnetite. Due to the difficulty in separation and extraction, the industrial titanium was not produced until the 1940s. Therefore, titanium is generally called rare light metal. Because different products in different fields need different titanium and titanium alloy products, people can process them into plates, rods, tubes, belts, wires and other shapes that can be further processed to meet the needs of different fields. Among them, titanium plates, rods, and tubes are the most widely used. The performance of titanium plates commonly used in the chemical industry is introduced as follows: I. Executive standard for titanium plates and titanium alloy plates: GB/T3621-2007

3、 Mechanical properties of titanium plate

IV surface quality 

The surface of titanium plate shall be smooth and clean, showing the natural color of metal. Plates are allowed to be delivered with sandblasted surfaces.

Slight darkening and local water stains are allowed on the titanium plate surface; Local defects, scratches, indentations, pits and other defects not exceeding half of the thickness tolerance are allowed, but the minimum thickness shall be guaranteed.

The titanium plate surface is not allowed to have cracks, peeling, oxide skin, folding, metal and non-metallic inclusions and other macro defects and traces of alkaline washing. The titanium plate is allowed to clear local defects along the rolling direction, but the thickness of the plate after removal is not less than the minimum allowable thickness. In addition, titanium plates shall not be layered.

5、 Application of titanium plate

Titanium and titanium alloys have low density and high tensile strength. In the range of - 253-600 ℃, their specific strength is almost the highest among metal materials. They can form a thin and hard oxide film in an appropriate oxidizing environment and have excellent corrosion resistance. In addition, it has the characteristics of non-magnetic and small linear expansion coefficient. This makes titanium and alloy first known as important aerospace structural materials, and then extended to shipbuilding, chemical industry and other fields, and has been rapidly developed. Especially in the chemical industry, titanium and titanium alloy products are used in more and more products, such as petrochemical, fiber, pulp, fertilizer, electrochemistry, seawater desalination and other industries, as exchangers, reaction towers, synthesizers, autoclaves, etc. Titanium plate is used as electrolytic plate and electrolytic cell in electrolysis and sewage desalination, and as tower body and kettle body in reaction tower and reactor

With the development of science and technology, the application fields of titanium materials are becoming wider and wider, such as medical treatment, automobile, sports and other aspects. Through these, it is also true that titanium, as a light metal, has more and more excellent characteristics that are recognized and determined by people, and it can replace other metals and integrate into our production and application fields at the fastest speed, even our bodies. The applications of heat resistant paint and titanium epoxy paint are numerous.