Titanium alloy is an indispensable new structural material in the aviation industry. The amount of titanium alloy in the new generation advanced aircraft body structure and its engine is more than 30%. The content of titanium alloy in aviation aircraft has become one of the important marks to measure the advanced of aircraft and engines.
Titanium alloys are based on titanium and are composed of aluminum, tin, vanadium, molybdenum, niobium and other elements or materials. Compared with other materials in aerospace, titanium and titanium alloys reduce the weight of the structure, improve the structural efficiency, improve the structural reliability, and improve the performance due to its low density, high specific strength, strong toughness, high corrosion resistance, high temperature performance, and non-magnetic properties. Airframe life, meeting high temperature and corrosive environment have irreplaceable effects. As the preferred material for aero engine fan, compressor wheel and blade and other important components, it is known as "space metal" and is an important strategic metal.
Second, the development of titanium alloys in the aerospace field
The industrialization of titanium alloy first began in the military and aerospace industries. Its application range has gradually extended from non-load-bearing components of aircraft to load-bearing structural parts. The long-term maximum operating temperature of titanium alloys has developed from the original 300 ° C to the present. 600 ° C.
In 1953, for the first time, titanium was used on the fire wall and nacelle of the DC-T engine produced by Douglas Company in the United States, and the history of titanium alloy application in aviation began. During this period, industrial pure titanium was used on military aircraft to manufacture rear fuselage heat shields, wind deflectors, tail covers, and other rare non-load-bearing components. The long-term maximum operating temperature of titanium alloys was 350-350 ° C.
In the 1960s, titanium alloy gradually replaced structural steel and was applied to load-bearing structural components such as aircraft flap rolling, bearing bulkheads, mid-wing box beams, and landing gear beams. IMI679, BT25, and BT9 were subsequently developed , IMI829 and other titanium alloys have increased the maximum operating temperature to 400 ℃ -500 ℃.
In the 1970s, the application of titanium alloys in aircraft structures expanded from fighter jets to large-scale military bombers and transport aircraft. Civil aircraft also began to use titanium alloy mechanisms. A Boeing 787 used up to 136 tons of titanium, accounting for 15 of the total aircraft mass %.
In the 1980s, titanium for civil aircraft gradually increased, and it has exceeded that for military aircraft.
At present, the amount of titanium used in aircraft has been further increased, close to 40%, and the long-term operating temperature has reached above 500 ° C. The amount of titanium used in the fuselage of the fourth-generation fighter F-22 has reached 38.8%, and the amount of titanium used in its F119 engine has reached 35%. IMI834 titanium alloy can reach 600 ℃.
3. Development Status of Titanium Alloys in the Aerospace Field
1.The industry chain of titanium alloys for the aerospace industry-middle and high-end titanium materials are in high demand
The industrial chain of titanium for aerospace includes the mining of titanium ore, the smelting of sponge titanium, the casting of titanium alloys, and the processing and production of titanium materials. Ilmenite and rutile are the main raw materials for the production of metal titanium and titanium white. After sulfuric acid oxidation and chlorination, carbon tetrachloride is obtained. After magnesium reduction, sponge titanium is obtained, which is then processed into various applications through smelting. Aerospace titanium and castings. China is one of the six countries in the world with a complete titanium industry from ore smelting to titanium production. The other five countries are the United States, Russia, Ukraine, Kazakhstan, and Japan. Among them, the United States, Russia, and Japan are traditional titanium industrial powers.
In China's entire titanium industry chain, the upper and middle reaches of the chain are in a situation of overcapacity, and the downstream high-end titanium materials are in a tight state. China is a country with large reserves of titanium ore resources, but titanium purity with higher purity still needs to rely on imports. The overall excess capacity of titanium sponge is severe, but the capacity of high-end sponge titanium for aerospace is still insufficient. In the field of titanium processing, the production capacity of ordinary titanium ingots remains, but high-end titanium ingots used in aerospace are in short supply due to increased demand, and almost all titanium for civilian aircraft depends on imports.
Market size
Because compared with other metals, titanium alloys have outstanding advantages such as low density, high specific strength, good high temperature performance, and strong corrosion resistance. Their application level has become an important indicator of the advanced level of aircraft structure material selection, and it also affects the combat performance of military aircraft. Important factors have been widely used in the aerospace materials market. USGS pointed out that the current global aviation titanium material accounts for about 50% of the total titanium demand; in the United States, the proportion of titanium used in the aviation field is even as high as 79%; Russia's 57% of the titanium is used in aircraft fuselage and engine fields .
The amount of titanium used in China's aerospace industry has maintained rapid growth. In 2017, China's titanium material output reached 55,400 tons, and titanium material demand was 46.745 million tons, while China's aerospace titanium sales reached 7619 tons, and the proportion of high-end titanium materials for aerospace increased from 10.1% in 2009 to 2017. 16.3% of the total annual growth rate of domestic aerospace titanium material sales from 2009 to 2017 reached 16%.
With the vigorous development of China's aerospace industry, both in civil aviation and military aerospace, there is a huge demand for high-end titanium materials. The new turbofan branch line commercial airliner ARJ21 uses 4.8% of titanium alloy. China's independently developed large passenger aircraft C919 and ARJ21-700 have completed their first flight. Its titanium alloy ratio is slightly higher than the Boeing 777's 8% consumption, reaching 9%. The single machine titanium content reaches 3.92 tons. As of March 2019, orders for C919 have reached 815, which is about 3194.8 tons of titanium alloy demand. China ’s latest generation of military aircraft ’s titanium alloy consumption has increased significantly, and the latest four generations ’fighter aircraft ’s titanium consumption has increased by more than double compared to the three and three and a half generation fighters. Even if the number of military aircraft produced each year remains unchanged, China's military demand for titanium alloys will also double.
3. Technical level of titanium alloy
China's high-end titanium related technologies have significantly improved. The vacuum consumable arc melting technology of large-size titanium alloy ingots has gradually solved the common problems of ingot shrinkage, high-density inclusions, low-density inclusions, and component segregation. The large-scale bar forging technology has gradually realized the mass production of aviation titanium alloy bars with a diameter of 300mm ~ 500mm, which has promoted the upgrading of relevant technical standards. With the rapid development of high-end titanium smelting and forging technology, the domestic level of titanium alloy materials for aviation equipment has continued to increase. Many titanium alloy materials have filled domestic gaps and basically met the domestic high-end market demand for titanium performance levels.
In addition, in recent years, advanced large-tonnage processing equipment has been newly built and introduced in China to improve equipment automation and efficiency, such as 8,000-ton electric screw presses, 40,000-ton large die forging machines, and 80,000-ton large die forging machines. There have also been major breakthroughs in the technology of wide-sheet thin-sheet enveloping and rolling, large-scale forging spinning forming, and integrated forming technology.
4. Industrialization level
In terms of enterprises, the companies that can mass produce aerospace titanium alloys in China include Baotai, Western Materials, and Western Superconductor. Baotai Co., Ltd. is the largest titanium material manufacturer in China. It can produce a variety of titanium processed materials, including titanium rods, wires, pipes, and plates. The annual production capacity of western materials titanium materials reaches 5,000 tons, mainly in sheet metal, which is the rising star of high-end titanium materials in China. Western Superconductor has a capacity of 4,950 tons of titanium alloy. The market share of titanium alloy products in the domestic aerospace titanium material market is approximately 23.90%.
In terms of products, plates, bars and pipes are currently the main titanium products, accounting for 47%, 22% and 13% of the total titanium materials, respectively. There are also differences in the application sites of titanium products in different product forms. Taking domestic C919 aircraft as an example, six titanium alloy grades have been selected. The categories include low strength and high plasticity, medium strength and medium toughness, medium strength and high toughness, high strength and high toughness, and system materials. The products cover forgings, thick plates, thin plates, and profiles. , Pipe, wire, etc.
In terms of application, aerospace titanium is mainly used in aircraft frame beams, landing gear, fasteners and engine fans, compressor disks and blades and other rotating parts. For example, the titanium alloys used in the C919 aircraft include CP-3, Ti-6Al-4V, and Ti-55531. The main parts are head, suspension, tail, outer wing, and center wing box.
Fourth, the future development prospects of titanium alloys
1. Equipment upgrades will drive demand for military aviation titanium
As of the end of 2018, there were 53,953 military aircraft in service worldwide. Among them, the United States ranks first with 13,398 military aircraft, and China has 3,187 military aircraft of all types, ranking behind Russia and ranking third in the world. In order to match the US Air Force, China will increase the number of military aircraft in the future.
At present, titanium alloys play an important role in the continuous iteration of military aircraft, and have become the main metal material selection for the third-generation aircraft, fourth-generation aircraft and supporting structural components of aero engine. According to Roskill statistics, it is expected that the proportion of titanium used in military aircraft will gradually increase to more than 20% by 2020. With the expansion and upgrading of China's military aircraft, the mass production of new aircraft will open up a new pattern of aviation titanium demand.
2. Civil aircraft localization provides growth momentum for aviation titanium
The localization of key materials for civil aircraft in China provides new growth momentum for high-end titanium alloy materials. The domestic aircraft C919 and ARJ21-700 have completed their first flight. As of March 2019, the order volume has reached 815. According to forecasts, C919 will occupy 1/5 of the global COMAC market in 2025, corresponding to the demand of approximately 2,000 aircraft. With a titanium content of 8,000 tons, assuming a loss rate of 80%, C919 will bring more than 40,000 tons of titanium alloy demand (excluding engines).
3. China's aviation titanium material sales maintain rapid growth, future demand is expected
With the growing demand for military aviation titanium and civil aviation titanium, China's aviation titanium sales will maintain rapid growth. In addition, the annual compound growth rate of China's aerospace titanium alloy sales is only 16%, which is far lower than the global proportion of aerospace titanium materials accounting for 50% of the total demand for titanium materials. The total demand for titanium will reach 218.6 thousand tons.