The present situation of Maglev Line and the Development of Aluminum in cars in China

Maglev train is a kind of rail transit which uses magnetic force or air flow to fly forward at the speed of 8mm~10mm in the space of off-orbit plane 30km/h~600km/h. At present, the speed 4000km/h train is under development. China is a global leader in R & D, construction and operation in this field. As of August 2020, five maglev lines have been put into operation.

The maglev train compartment is made of all-aluminum material. In this paper, the aluminum material of carriage structure is introduced, especially the properties of 6N01 and 7N01 aluminum alloy. It is hoped that the maglev car aluminum alloy with 6N01 and 7N01 properties can be developed in our country. China will start the construction of Beijing-Guangzhou-Macao, Shanghai-Guangzhou and other high-speed maglev lines. This will be a big project for the construction of maglev lines, and the aluminum of maglev equipment will also become a specialized branch.

According to the Guangdong Provincial Land and Space Plan 2020-2035 released in February this year, two high-speed maglev corridors will be reserved in the space of Guangdong Province. they are the north-south longitudinal Beijing-Guangzhou-Macao high-speed maglev corridor and the Shanghai-Shenzhen-Guangzhou high-speed maglev corridor along the east-west coast. The state also has a plan to build a high-speed maglev train in Beijing-Guangzhou Dawan area, with a train speed of 600km / h. although the construction cost, specific route, opening time and other details have not yet been announced, preliminary work has begun. The "outline for the Construction of a Traffic Power" issued in 2019 proposes that the 600km/h high-speed maglev system should be arranged as a whole. CRRC Sifang and universities in Shanghai and other places have also carried out related research and development. In June 2019, the high-speed maglev test prototype of the speed 600km/h was successfully tested on the experimental line of Tongji University in Shanghai, and achieved the desired results. In addition, China also plans to build high-speed maglev lines from Shanghai to Hangzhou and Chongqing to Chengdu.

The maglev train in China

Development process and present situation

The development of maglev in China can be divided into three stages: the period from 2002 to 2015 is the period of introduction and starting; the period from 2016 to 2020 is the period of self-reliance R & D and construction; in 2021, China has entered a period of great development since the 14th five-year Plan. Magnetic levitation technology and line construction and operation.

According to the speed, the maglev train can be divided into medium and low speed (running speed 30km/h~200km/h), high speed (running speed 200km/h~400km/h) and speed (running speed greater than 400km / kg / h, usually 600km/h).

The first maglev line starts to operate.

China's first maglev railway was operated in Shanghai in January 2003, and all vehicles and technologies were introduced from Germany. Shanghai maglev line is the first commercially operated high-speed maglev line in China and the world, starting from Longyang Road Station of Shanghai Rail Transit Line 2 in the west to Pudong International Airport in the east, with a total length of 29.863km and a high speed of 430km / h. the whole journey takes only 8 minutes. Its operation is based on the opposite attraction effect of the maglev electromagnet installed on the bogies on both sides of the train and the magnets laid on the track. At the same time, the maglev car is equipped with an electromagnet and a coil is installed at the bottom of the track. once powered on, the polarity of the magnetic field produced by the bottom coil is always the same as that of the electromagnet on the train, and the two repel each other, but the force below is much greater than that above, which makes the train float, and there is a push to make the train "fly" forward.

The first domestic maglev line is put into commercial operation in Changsha

China's first domestic maglev line was operated in Changsha in May 2016. China has its own intellectual property rights. Medium and low speed maglev trains are designed and manufactured by Zhuzhou Electric Locomotive Co., Ltd., with three sections assembled, and the round aluminum alloy car body is decorated with a "China Red" waistline. The car is equipped with soft seats, floor-to-ceiling windows and dark stainless steel handrails. The warm tone runs through the atmosphere in the compartment like the cabin of a large civil aircraft. This new type of medium-and low-speed maglev train is the result of cooperation among domestic rail transit research and development institutions such as Zhuzhou Electric Locomotive Co., Ltd., Southwest Jiaotong University, Zhuzhou Electric Locomotive Research Institute of China Railway Corporation and the second Hospital of China Railway Corporation. It is designed with a high speed of 100km / h and a large capacity of 600 passengers. It has many advantages; due to no wheel-rail friction and Tackle, the operation is extremely quiet; the use of special rail design, the limit reduces the risk of train derailment and rollover, with the nature; reasonable cost, than the railway and medium transport volume of light rail lower than the railway and medium transport volume of light rail respectively lower than the railway and medium transport volume of light rail by 1 canvas 3 and 1 canvas 4; small turning radius, only 50 meters; strong climbing ability, can run flexibly around buildings or mountains, can drive into residential areas. The radiation of the medium and low speed maglev train with Chinese characteristics is smaller than that of the razor, taking into account environmental protection, economy and sex, and can be used in densely populated areas and scenic spots and tourist areas with high requirements for environmental protection.

Tianjin Binhai Airport M3 demonstration Line completed in half a year

The M3 medium-and low-speed maglev short demonstration line of Tianjin Binhai Airport, which was put into operation in 2017, was completed in less than half a year. Its magnetic power technology was introduced from American Maglev aircraft Company and American Magnetic Power Company, and established Maglev Engineering Technology (Tianjin) Co., Ltd., which is responsible for operation, and built commercial test lines in China and the United States at the same time. Centering on its horizontal rare earth permanent magnet diameter Synchronize motor, permanent magnet levitation, permanent magnet guidance and its control technology, the company focuses on the development of medium and low speed maglev trains. intelligent automatic production of transmission lines and logistics management lines, mineral transmission lines and lifts without cables and electric room.

Beijing medium and low speed maglev S1 line

Beijing S1 line also adopts medium-and low-speed maglev technology, with six carriages grouped, which is Beijing's first maglev line, starting from Shimenying Station in Mentougou District in the west and Shijingshan Apple Garden Station in the east. The total length of the line is 10.236 km, including the boarding and boarding time. The whole journey of the train does not exceed 20 minutes. The carriages are made by Tangshan Rail bus Co., Ltd. the cost of each car is 8 million yuan, which is about 2 million yuan more expensive than the subway car.

High-speed maglev experimental center is stationed in Qingdao National High-speed Train Innovation Center.

Five projects, such as high-speed maglev experimental center and high-speed maglev trial production center, were stationed in Chengyang District, Qingdao in January 2018. These five projects mainly come from the urban rail transit innovation capacity building of the National Development and Reform Commission and the key science and technology of the 13th five-year Plan of the Ministry of Technology. Among them, the rail vehicle system integration national engineering laboratory project will break through the technical bottleneck of urban rail transit verification in China, and it is of great significance to form a unified test standard system.

High-speed maglev train focusing on 600km/h

The technical scheme of the high-speed maglev system with a speed of 600 km/h was reviewed by experts in CRRC Sifang Co., Ltd. in 2018, and the prototype car will be put on the test line in 2020. The program is led by Sifang Co., Ltd. Its passing evaluation indicates that the national key research and development project of "key technology of high-speed maglev transportation system" has achieved substantial and important results, and can enter the next stage of construction and design. According to the plan, Sifang should complete the prototype manufacturing in 2018 and the 5km test line verification of the 600km/h prototype car in 2020, all of which have been successfully completed. We know that at present, the high speed of the high-speed railway is 350km / h, the cruise economic speed of civil aircraft is 800km / hm2 / 1000km / h, and the high-speed maglev transportation system with speed 600km/h can fill the speed and form a complete transportation network.

Sino-Japanese joint development of high-speed maglev train

The maglev train is levitated by magnetic force and driven by natural air flow at a speed of 500km/h. China and Japan are jointly developing a high-speed maglev train called Pelican, which is operated by a robot and is a high-speed unmanned maglev vehicle.

The design of the maglev train is inspired by the flight of airplanes and pelicans, so it gets its name, according to Professor Lai Chenguang, a scientist at Chongqing University of Technology who participated in the research and development of the "Pelican" high-speed train. Pelicans use variable flying technology to gain lift between air masses at different speeds and free Fly in the sky, so the maglev vehicle is levitated, using short U-shaped wings and fast-moving air to fly close to the ground. It floats by magnetic force to overcome gravity, while it flies forward by fast-flowing air and is a natural energy-driven, pollution-free train. The prototype of the pelican train and the second generation of the pelican train were trial-produced in 2017 and the real car test was completed at the University of Tokyo.

Permanent magnet straddle monorail maglev vehicle

China's maglev car was successfully trial-produced in 2016, known as the "air train", is a very distinctive rail transit, its track is not the traditional two parallel routes, but a single reinforced concrete beam, the wheels are rubber, riding on the track beam, it is one of the transport equipment for urban backbone, auxiliary lines, airport connections and sightseeing. It has strong climbing ability, small turning radius, rubber wheel, can climb steep slopes, make sharp turns, and has strong line adaptability, so it is especially suitable for cities with complex topography and geology, such as mountain areas, river valleys and so on. it can also travel through the bustling center of plain cities, tourist routes and so on. The cost of the project is low and the area is small. Its structure is simple, the cost is low, the construction period is short, the cost is less than 250 million yuan, km, is about 1x3 of the subway; its track beam is narrow, covers an area of only 1mm and 1.5m, and can be erected on the isolation belt in the center of the road. The straddle monorail train runs completely closed, fast, and does not interfere with other traffic forms, with a high speed of 80km / h and an average speed of 30km / hm2 / h, which is similar to that of the subway; it belongs to a rail transit system with medium capacity, with an one-way capacity of 10,000 passengers per hour, which is close to that of type B subway trains. The seat is comfortable, the noise is low, the vibration and noise caused by the rubber wheel are quite low, which is much lower than that of the wheel-rail system, it has almost no impact on the surrounding environment, the electromagnetic radiation is negligible, and most of the monorail lines are elevated structures, with a wide field of vision and a panoramic view of the city and the wind shadow along the line.

China's "version 2.0" fast maglev train will be off-line in October 2012.

The speed of this maglev train is 160km / h. it is independently developed by Zhuzhou Electric Locomotive Co., Ltd. it has the advantages of faster, lighter and more passengers than the first medium-and low-speed train of Changsha Maglev Express Line in China. It has the characteristics of strong slope climbing ability, small turning radius and low noise. It is suitable for operation within cities, between urban areas and satellite cities, between urban agglomerations and scenic spots with complex topography. It is the fist track product of urbanization construction, "Belt and Road Initiative" construction and "going out".

Guangdong Qingyuan Maglev Tourism Line was put into operation in mid-2021.

Qingyuan medium-and low-speed maglev tourism line was built in 2016 and put into operation in mid-2021. China Railway Maglev Transportation Investment Construction Co., Ltd. and Qingyuan municipal government invested 10 billion yuan in construction, with a length of 30 km. The new medium-and low-speed maglev train is manufactured by CNR Changchun bus vehicle Co., Ltd., and will be off-line in December 2020.

The R & D and line construction of new projects in traffic power are in full swing.

In addition to Qingyuan maglev is about to be put into operation, Xinjiang Urumqi maglev line and Chengdu-Deyang maglev line are under construction, Shanghai-Hangzhou line is also under construction, high-speed maglev line construction of Shanghai-Shenzhen line and Beijing-Guangzhou line 600km/h has also been put on the agenda, or construction will begin during the 14th five-year Plan period. If a simple calculation is carried out according to the speed of 600km/h, it takes about 3 hours to travel from Shenzhen to Shanghai, which is about 1500 km apart, and about 2200km from Shenzhen to Beijing. If you take the maglev car of Beijing-Guangzhou-Macao Expressway, you can get there in less than 4 hours. In addition, the preparatory work for the Chongqing-Chengdu high-speed maglev line is going on day and night.

Development of a high-speed maglev flying train with a speed of 4000km/h

China Aerospace Science and Industry Corporation is developing a high-speed flight train, reaching 1000 km/h, and finally reaching 4000km/h. This kind of flying train uses superconducting maglev technology to reduce friction resistance and realize supersonic flight in low vacuum large diameter tubes. It will be gradually realized according to the three-step strategy: step by step, the transport capacity will be used to build a regional inter-city flying train network; the second stage will reach 2000km / h to build a national super flying train network; and the third stage will reach 4000km / h to build a "Belt and Road Initiative" traffic network.

At present, the high-speed flying train project has joined more than 20 scientific research institutions at home and abroad to form a domestic and international high-speed flying train industry alliance, which has more than 280 patents in related fields. The strong current needed for the operation of this kind of maglev flying train is transmitted by superconducting high purity aluminum, so in addition to the large amount of aluminum needed to make the carriage, the superconducting transmission system also needs a considerable amount of high purity aluminum conductor. High purity aluminum conductor is a kind of high-tech products, and its preparation and processing technology is higher than that of traditional industrial pure aluminum conductor.

The research and development base of China's high-speed flying train project is located in Wuhan, which is likely to form a high-speed flying train network extending in all directions in the future. China will also vigorously promote the internationalization of maglev lines and become another export product like high-speed rail. After the operation of the Changsha maglev line, it has become another gorgeous business card for China's railway construction. Singapore, Germany, Brazil and other countries have sent delegations to inspect it. China is also preparing to export high-speed maglev trains, and Japan's Donghaibin passenger Railway Company, which plans to open a maglev central shinkansen in 2027, is also seeking to export maglev railways to the United States. China and Japan will also compete fiercely in the field of maglev railway technology and construction in the international market.

Powerful aluminum

Provide backing for the rapid development of maglev trains

High-speed rail vehicles are mainly made of aluminum alloy, maglev train cars should be made of aluminum, platform ceilings and station buildings should also be made of aluminum. Aluminum is a material with good performance-to-price ratio for the car structure, of course, some aluminum matrix composites may be used in the future, because the car is all-aluminum, the lighter the better, the lighter the gravity to overcome, the less the force to float it. In addition to aluminum in carriages, the construction of railway facilities also requires a considerable amount of architectural-structural aluminum. Interior decoration, air conditioning, seats and ventilation systems are also mainly made of aluminum alloy, and some vehicles are floated by permanent magnetic force. if floating with a superconducting magnetic field, a high purity aluminum wire system is needed to transport current. Each car needs to purchase aluminum for the building-structural aluminum to calculate the quality for 45t/km.

Aluminum for carriage structure and construction

Commonly used aluminum compartments are 5005-0 plate, 5005-H14 plate, 5005-H18 plate, 5052-0 plate, 5083-0 plate, 5083-H112 profile, 6061-T6 profile, 6N01-T5 profile, 6063-T5 profile, 7N01-T4 plate, 7N01-T5 profile, 7003-T5 profile. 6N01 and 7N01 are new alloys developed in Japan. 7N01 alloy was formed in 1969 and 6N01 was introduced in 1980. The N in the brand stands for (Nippon) of Japan. The aluminum materials and compartments used in maglev cars are basically the same as those used in high-speed rail and subway all-aluminum cars.

6N01 alloy

6N01 alloy is a kind of Al-Mg-Si alloy, its composition (mass%): Si0.40~0.9,Fe0.35,Cu0.35, (Mn+Cr) 0.50Magnesia 0.40wt% 0.8 Magneto Cr0.30recoveryZn0.25, other impurities 0.05, totaling 0.15, the rest are Al. 6N01 alloy is a medium strength extruded alloy with lower strength than that of 6061 alloy, extrudable profile with complex cross section, good corrosion resistance and surface treatment, and can be used in the manufacture of vehicles, automobiles, land structures and marine parts.

6N01 alloy is a kind of alloy which can be strengthened by heat treatment. after on-line quenching, T5 material is artificially aged at 170C ~ 180C for 8h and T6 at 525C ~ 535C, artificial aging (170,180C) ℃ / 8h. Its density is 2.70g / cm ~ 3, the solidus temperature is 652 ℃, the liquidus temperature is 615 ℃, the thermal conductivity of T5 material is 188W/ (m ·℃) and the electrical conductivity is 46% IACs at 20 ℃. The typical mechanical properties at room temperature are shown in Table 1.

The tensile elastic modulus, shear modulus and Poisson coefficient of the alloy T6 are 68900MPa, 25800MPa and 0.33 respectively. 6N01 alloy has good corrosion resistance, in fact, there is no stress corrosion cracking and exfoliation corrosion; good weldability, extrusion properties, extrudable thin-walled large profiles, good surface treatment performance, but low machinability because of its low strength.

7N01 alloy

7N01 is a kind of Al-Zn-Mg-Mn alloy, which is equivalent to 7B05 alloy in China, its composition (mass%): Si0.30,Fe0.35,Cu0.20,Mn0.20~0.7,Mg1.0~2.0,Cr0.30,Zn4.0~5.0,Ti0.20,V0.10,Zr0.25, other impurities 0.05, a total of 0.15, the rest of Al. The alloy has good weldability, poor formability, good cutting performance, good surface treatment performance, high strength and good corrosion resistance. other properties are similar to those of American 7005 alloy, which can be used to manufacture parts of vehicles and land structures. 7N01 is a kind of wrought aluminum alloy which can be strengthened by heat treatment. The annealing temperature is about 415C, and the solution treatment temperature of the semi-finished product is about 450C. The aging treatment process of T4 state is more than one month at room temperature, and the treatment process of T5 and T6 state is about 120 ℃ × 24 h.

The density of 7N01 alloy at 25 ℃ is 2.78g / cm ~ 3, the liquidus temperature is 620C ~ 650C and the linear expansion coefficient is 23.6x 10 ~ (- 6) / ℃. The mechanical properties at room temperature are shown in Table 2. The corrosion resistance of the alloy is good, but it has the tendency of stress corrosion cracking. The natural potential of T4 material to calomel electrode is-940.0mV, the pitting corrosion potential of T6 material to calomel electrode is-919.6mV in 3.5%NaCl solution, and the pitting potential of T6 material to calomel electrode is-951.5mV. In 3.5%NaCl solution, the pitting corrosion potential of T6 material to calomel electrode is-814.6mV. Other properties are similar to those of American 7005 alloy.

Concluding remarks

China is already a global maglev line, carriage technology research and development, construction, operation and other aspects, China has more than self-supply of construction materials. The author hopes that Beijing-Guangzhou-Macao, Shanghai-Shenzhen constant Speed (600km/h) maglev lines can be put into operation before 2035, and strengthen the export of medium-and low-speed and high-speed maglev technology and line construction, especially for the exports of areas along the "Belt and Road Initiative" line, vigorously develop two or three maglev car structure extruded aluminum alloy products with better performance than 6N01 and 7N01, as well as aluminum alloy products suitable for 600km/h speed.