There is a strong demand for aluminum on the rise of the three major civil aircraft.

The three major civil aircraft mentioned in this paper refer to the ARJ regional airliner, the C919 airliner and the Sino-Russian long-distance trunk line wide-body airliner CR929. The regional airliner can seat 70-90 people, and the trunk airliner can seat more than 150 people.

ARJ regional airliner

ARJ21 is the abbreviation of the English name "Advanced Regional Jet for the 21st Century", which means the new generation of regional jet in the 21st century. It is a new regional airliner with medium and short-range turbofan engines with 70-90 seats. There are four types of basic airliners, extended airplanes, freighters and business jets in the family.

ARJ21 is the first regional airliner independently designed and manufactured in China. The various parts of the airframe are respectively produced by four domestic aircraft manufacturing companies, and a large number of international mature advanced technology airborne systems are adopted. Engine, avionics, power supply and other systems are all purchased through competitive bidding around the world. Among them, some parts are made in China, and some products are handed over in China.

In December 2003, ARJ21-700 manufactured parts in Chengdu aircraft Company, Shenyang aircraft Company, Xi'an aircraft Company and Shanghai aircraft Company at the same time. On December 21, 2007, the final assembly line of Shanghai aircraft Factory was put off the line. In November 2008, I successfully made my maiden flight in Shanghai. In March 2015, the first flight demonstration flight was completed.

On November 29, 2015, the 106th plane piloted by Chengdu Airlines flew directly from Shanghai Comac Airport to Chengdu Shuangliu Airport, delivered to Chengdu Airlines, and was put on the market in March 2016. it was initially launched on seven routes from Chengdu to Beijing, Shanghai, Guangzhou, Shenzhen, Wuhan and Xi'an. Since then, domestic routes have all their own knowledge for the first time.

The Made in China regional jet with property rights is a major event in the history of the development of China's aviation industry. It took 14 years for ARJ21-700 regional airliner to be put into operation from April 2002 to March 2016. What aluminum alloy and aluminum materials are used in ARJ21 airliners?

On January 23, 2017, Xu Lejiang, vice minister of the Ministry of Industry and Information Technology, pointed out at the annual working meeting of the upstream and downstream cooperation mechanism of aluminum for civil aircraft that the Ministry of Industry and Information Technology should formulate a key work plan for 2017 as soon as possible, and production units should step up efforts to tackle key problems in accordance with the requirements of airworthiness certification. We will speed up the progress in the development and application of key brands of aluminum, and strive to make phased progress in 2017.

ARJ2I regional airliner is basically made of aluminum alloy, the quality of aluminum parts is more than 75% of the net mass of the aircraft, almost all kinds of commonly used aluminum alloy, but some are used more, some are used less, whether it is deformed aluminum alloy, or cast aluminum alloy, from skin plates to small rivets, there are many kinds, with a quantity of more than 400,000.

The total number of parts of the ARJ21 airliner is over a million, but the fasteners are the most, and rivets take the first place in the fasteners. Rivets may have been around for thousands of years, and they have been used in airplanes for at least 119 years.

The most commonly used aluminum materials in the main structure of ARJ2I regional airliners are 2-series and 7-series alloys, and they are all the latest generation of alloys. The aluminum used in the prototype for forensics is all provided by Alcoa. The sheet comes from the (Iowa) Davenport Rolling Plant in Iowa (Daven-port Works), extrusions and forgings are produced by Lafayette plant (LafayetteWorks), and some extrusions come from Changguang Aluminum Company of Korea, which is a wholly owned aluminum extrusion company of Alcoa in South Korea. 2-series and 7-series alloys account for 98% of the total amount of aluminum in the main structure of ARJ21.

Aluminum materials for ARJ2I regional airliners can be all made in China.

ARJ21 regional airliner is the first medium-sized airliner independently designed and manufactured in China with all independent intellectual property rights. Regional airliner refers to the aircraft with less than 100 seats. According to the plan of Shanghai aircraft Factory, by the end of 2016, 5 aircraft will be paid for, including 2 90-seat aircraft and 3 78-seat aircraft. It is expected that 30 aircraft will be delivered in the next five or six years and by 2035.

880 aircraft can be delivered, with an overall manufacturing target of 50 aircraft per year and a first-phase target of 30 aircraft per year. According to the plan, the aluminum used can reach 100% domestic after 2020. The upstream and downstream cooperation mechanism of civil aircraft aluminum has been established under the leadership of the Ministry of Industry and Information Technology, which will greatly promote the localization process of aluminum needed for ARJ21 aircraft.

At present, about 20 enterprises in China, including Northeast Light Alloy Co., Ltd., Southwest Aluminum (Group) Co., Ltd., and Chinalco Northwest Aluminum Co., Ltd., can produce aluminum alloy plates, foils, shapes, tubes, bars and forgings for ARJ21 airliners. Their equipment is world-class, there is an enterprise from the Austrian Alberna (Ebner) company introduced a T77 processing aging furnace, the furnace temperature setting temperature ±1 ℃, furnace gas temperature accuracy ±2 ℃, plate temperature uniformity ±1.5 ℃, veneer temperature uniformity ±1 ℃, can handle the plate size (mm): thick 4000ft 250, width 1000mm 4300, length 2000cm 39000, veneer maximum mass 25 tons. Among the aluminum materials used in ARJ21 airliners, it is difficult to produce T77 state materials. As long as this material can be produced, the batch supply of all other materials is not a problem, and equipment plays an important role in the production of this material.

Aluminum alloy is the main material for ARJ2I aircraft, and aluminum parts account for 75% of the aircraft's net weight (24955 kg), or about 50 tons of aluminum (including castings and forgings), that is, 50 tons of aluminum; structural steel and stainless steel account for 10%; composite materials account for 8%; titanium alloy 2%; other materials account for 5%. Before 2020, if 30 planes are produced each year, the maximum annual consumption of aluminum will be 1500 tons.

It must be emphasized that the performance and indicators of the aluminum products supplied must fully meet or exceed those imported from Okonink Aluminum Co., Ltd., which are used to manufacture prototype forensics machines, so as to fully replace imported products, at the same time at a reasonable price and competitive in the international market.

T77511 alloy is used to make wing upper panel, and the landing gear joint is forged with 7055-T77 alloy. Among the 7 series alloys, 7055 alloy has the highest average total content of alloying elements, which is 12.35%, and the average total content of iron and silicon is the lowest, only 0.125%, so it is difficult to cast large flat ingots and has a large tendency to cold cracks. so far, we can not cast large flat ingots of some specifications economically.

The amount of rivets is nearly 400000.

Since the advent of the aircraft for more than 120 years, the riveting of parts is an indispensable connection process, large strategic transport aircraft and A380 super-large aircraft each use millions of rivets. For quite a long time in the future, riveting will still be the main process for the connection of spare parts, but with the passage of time, the improvement of design and the progress of welding technology, the workload of riveting will be reduced, but the speed of reduction will be slow. For example, a civil aircraft of the same size as an ARJ2I airliner used about 600000 rivets per aircraft 30 or 40 years ago, but now it still needs more than 400,000.

The rivet alloys used for ARJ21 regional airliners are 2014, 2219, 3003, 5052, 5056, 7050 alloys, 2219 alloy rivets are used for riveting high-strength internal and external structures, and 7050-T73 alloy rivets are used for riveting high-strength corrosion-resistant structures. Rivets are treated by sulfuric acid anodizing and dichromate sealing before riveting.

Cast aluminum alloy

Some cast aluminum alloys are also used in the manufacture of ARJ2I regional airliners, although the dosage is much less than that of deformed aluminum alloys, but it is also indispensable. For example, 356 and A356 alloys are used to cast structural parts with complex shape and structure, thin wall thickness and medium load, instrument accessories, engine parts and fuel pump shell, which are aluminum-silicon-magnesium alloys, equivalent to China's ZL101,. They all contain 6.5%~7.5%Si, 0.25% mg and 0.45% mg. A356 alloy is an improved type of 356 alloy, but it has higher mechanical properties because of its low impurity content and the addition of a small amount of grain refinement elements.

ARJ21 aircraft cast aluminum alloy also: 413,360,355, A357, Tens-50, 380, A380 alloy and so on.

The deformed aluminum alloy 2524murT3 used in ARJ21 regional airliners accounts for about 60% of the total plate consumption, followed by 7050, 7150 and 7055 of 7 series alloys, accounting for about 35%. They are all used in the state of T77. T77 indicates that after solution treatment and aging treatment, the strength of the material is lower than the maximum value it can reach, but the resistance to stress corrosion cracking and intergranular corrosion has been greatly improved.

2524-T3 alloy is a good 2-series alloy, and all the skins of the ARJ21-700regional airliner are made of its pre-stretched plates. It includes fuselage skin, rear fuselage skin, subwing fuselage skin, fuselage skin docking with the wing, flap skin, flap skin, vertical tail skin, elevator skin, flat tail skin, spoiler skin, rudder skin and adjustment piece, aileron skin and adjustment piece, seam wing skin and elevator adjustment piece. 2524 alloy was born in 1995 and registered with the American Aluminum Association in the same year, while 2024 alloy was born in 1934. 2524 alloy is the sixth generation of 2024 alloy family, and their main components (Cu, Mg, Mn) are roughly the same.

7 series alloy

In the structural manufacturing of ARJ21 regional airliners, the most commonly used is 2-series 2524 alloy, accounting for about 60% of the total aluminum alloy, followed by 7-series alloy accounting for about 35%, mainly using three kinds of alloys: 7050, 7150, 7055, all of which are new super-strength aluminum alloys developed by Alcoa. These three kinds of 7-series aluminum alloys prop up half the sky of the ARJ21 airliner. 7050 alloy is a kind of high purity superhard aluminum, not only the content of impurity Fe and Si is low, but also the content of Mn is very low. The brittle inclusion phase in the microstructure is greatly reduced, the ratio of zinc to magnesium is increased in the principal composition, and Zr is used instead of Cr as grain refiner. Due to the improvement of these components and artificial aging treatment, 7050 alloy has excellent comprehensive properties, such as high fracture toughness, high fatigue strength, good damage tolerance, good stress corrosion resistance and so on. Another outstanding advantage is its high hardenability, which is especially suitable for manufacturing thick plates and forgings and thick cross-section parts. In aircraft, 7050 alloy is mainly used to manufacture main load-bearing structures that require high strength, high stress corrosion and exfoliation corrosion resistance and good fracture toughness, such as fuselage frame, partition, wing panel, wing beam, wing rib, landing gear supporting parts and rivets, etc. When the temperature increases, the strength of 7050 alloy decreases, so the long-term service temperature should not exceed 125C.

C919 aircraft

China's independently developed C919 large airliner began in 2008, went offline at Comac on November 2, 2015, and made its maiden flight on May 5, 2017. Its main technical parameters: basic mixed class layout 158 seats, total length 38.9m, height 11.95m, Jizhan 35.8 m, standard flight range 4075km, direct flight from Beijing to Singapore, to and from all domestic cities, the maximum range is 5555km, compared with Boeing B737 aircraft, it has the characteristics of safer, lighter, higher power, faster, more comfortable and so on.

What kind of aluminum alloy is used in C919?

Although all the aluminum used in the C919 prototype is imported, it is mainly for the need of airworthiness certification. Starting from the second aircraft, the consumption of domestic aluminum will be more than one batch after another, more and more year after year. The localization rate of aluminum for C919 aircraft in 2018 is more than 35%, and the localization rate of aluminum in 2022 is expected to reach 100%. However, some Al-Li alloys and aluminum matrix composites may need to be purchased. Because it takes six or seven years to develop all the new aluminum materials needed to develop a new generation of aircraft, even in industrially developed countries.

Most of the nose, front fuselage, central wing and middle rear fuselage of the C919 are manufactured by domestic aviation enterprises such as AVIC. Flight control systems, wheel braking systems, auxiliary power units and navigation systems are provided by Honeywell.

The engine, made by (GE) of the US General Electric Company and Safran of France, is more powerful and powerful than the existing Airbus A320 and Boeing B737 aircraft, but the fuel consumption is much lower, the operating cost is about 10% lower than their use cost, and the carbon emissions are reduced by 50%.

The C919 adopts supercritical wings independently developed in China, which increases speed and saves fuel. Several important indexes such as sound speed ratio, navigation characteristics and stall characteristics of C919 are better than those of similar foreign aircraft, and the speed is also faster than their. Its cabin is equipped with a damping system to cushion bumps, and there are separate vents in the inner wall of the cabin, which can better adjust the change of air pressure in the cabin; the seat in the middle of the cabin is 12.7mm wider than the international aviation standard seat, so passengers feel more comfortable.

In the material selection of C919 aircraft, a large number of traditional aluminum alloys are selected, such as 7075-T62, 7075-T73, 7050-7452, 7075-T73511, 7050-T77511, 7075-T7351, 7050-T7452, 7150-T77511, 7075-T6, 7055-T7751, 7055-T76511, 7085-TT651, 7085 T7452; 2024-T42, 2523-T3, 2024-T3511, 2024HDT-T351, 2026-T3511, etc., and also selected a certain number of third generation aluminum-lithium alloys: 2198-T8, Al-Li-Sc-T8, 2096-T8511, 2099-T83 and so on. 7 series aluminum alloy is the most widely used.

The front fuselage, middle fuselage, middle and rear fuselage, nose and wing structure of C919 are almost all made of aluminum, while engine hanging, vertical tail, flat tail, front part of rear fuselage, rear pressure frame, middle part of rear fuselage and center wing are made of composite materials or titanium alloy forgings. In addition to the main parts of the above section are made of today's high-end traditional 2-series and 7-series aluminum alloy, some important structural parts are made of aluminum-lithium alloy, some minor parts and functional parts are made of other aluminum alloy, such as air conditioning system, oil pipe, luggage rack, sanitary facilities and so on. Overall, the total mass of aluminum alloy workpieces of C919 aircraft accounts for 65% of its total net mass. The C919 is assembled by the connection of more than one million parts. The connection between aluminum alloy parts and other parts, such as the connection between the engine and the wing, plays a very important role in aircraft manufacturing. All the connection fasteners are produced by Alcoa's two plants in Suzhou, Jiangsu Province, China, and some may be imported. The ancient riveting method is still the main connection process for aircraft parts. The fuselage of C919 is assembled from 16,700 sheet metal parts. More than 60,000 rivets are used, some of which are 2-series alloys and some are 2-series alloys containing lithium.

Most of the domestic aluminum materials needed to manufacture C919 aircraft are provided by China Aluminum Group Co., Ltd. For example, Southwest Aluminum (Group) Co., Ltd., which belongs to it, has successfully trial-produced precision die forgings for passenger observation window frames and landing gear wheels in November 2017, in addition to providing 30 specifications and more than 600 aluminum alloy forgings for C919, filling the gap in this field in our country. These die forgings have the characteristics of high strength, high toughness, strong fatigue resistance and high corrosion resistance. they are the key structural components of aircraft, mainly used in wings, wing moving surface, fuselage central wing, landing gear and so on.

On November 10, 2017, the first C919 plane took off from Shanghai Pudong Airport. After a 2-hour and 24-minute flight, the C919 successfully arrived at Xi'an Yanliang Airport with a flight distance of more than 1300 kilometers, which is a very important step for China to realize its dream. The New York Times commented that C919 symbolizes the industrial power of a rising superpower and its dream of dominating a new technological era. Song Lei, a professor from the School of Government Management of Peking University, said that the successful maiden flight of the C919 has at least three major meanings: it once again demonstrates the importance of a complete industrial system to a big country like China; this is the success of China's new R & D system. In the process of R & D, Chinese enterprises have realized R & D that focuses on us and co-ordinates global R & D forces.

It indicates that China's independent innovation has entered a new stage.

As of December 5, 2017, the total number of orders for C919 aircraft signed by Comac with customers at home and abroad has reached 785.

CR929 long-distance trunk wide-body airliner will be built in 2021

On May 29th, (CRAIC), a Sino-Russian international commercial aircraft company, was officially established at the headquarters of the Commercial aircraft Corporation of China ((COMAC)), and held a press conference on the naming of CR929 and LOGO, a joint venture company. The series of aircraft, officially named CR929, letters C and R for Chinese (China) and Russian (Russia); number 929 respectively, also have far-reaching symbolic significance: 9 means Tian Chang Di Jiu (Eternal Dumpling) in Chinese culture, 2 is the actual number of the project, and the first narrow-body passenger aircraft developed by China itself is code-named C919.

Sino-Russian International Commercial aircraft Co., Ltd. is a joint venture between China Commercial aircraft Co., Ltd. and Russian United Aviation Manufacturing Group (UAC). Its LOGO is a pair of wing patterns, representing sincere cooperation, the two wings take off, the red wings represent China, and the blue wings represent Russia.

CR929 will complete its maiden flight in 2025, so the final assembly should be completed in the second half of 2023. 80% of the required aluminum can be supplied in China, and roughly less than 20% need to be imported, mainly aluminum matrix composites and high-grade new generation Al-Li alloy materials. By 2045, it is planned to sell 1000 aircraft. if the purchase of aluminum per aircraft is calculated at 120 tons, the total purchase of aluminum will be about 120000 tons, with an average purchase of 4800 tons per year in 25 years.

In fact, the form of cooperation between Russia and China in the production of CR929 trunk aircraft is the so-called technical partnership. China is responsible for design and manufacturing, and Russia acts as a technical partner. Within this framework, China can gain experience in long-distance trunk aircraft manufacturing that we do not have, and at the same time obtain composite technology that is still short. The project budget of the Sino-Russian International Commercial aircraft Corporation is about 13 billion US dollars.

According to the plan of Sino-Russian International Commercial aircraft Co., Ltd., the first flight will be completed in 2025. By 2045, 300-1000 aircraft will be sold. According to Russia's techno-economic demonstration of the CR929 project in December 2016, the basic model has a price of $113.5 million to $117.8 million, compared with $264 million for the Boeing B787-9 and $300 million for the B787-10. The price of Sino-Russian co-built aircraft is less than 50% of that of American aircraft.

According to the division of labor, our country is not only responsible for the final assembly, but also responsible for fuselage assembly and sales. All preparatory work was completed in December 2020, and the first prototype was built in early 2021, using roughly the same aluminum as the C919 aircraft, and it is estimated that about 20% of aluminum, such as aluminum matrix composites and aluminum-lithium alloys, may need to be imported from Russia or other countries.