As a typical light metal, aluminum alloy is widely used in foreign automobiles, the main aluminum alloy parts of foreign cars are piston, cylinder head, Clutch Shell, Oil Pan, bumper, heat exchanger, bracket, wheels, body plate and decoration parts.

At present, the United States, Japan, Germany is the automotive use of aluminum alloy most countries, such as the German Volkswagen Audia8, A2, Japan's NXS body with 80% of aluminum alloy. In addition to Shanghai Santana, Faw Audi and Jetta (are imported production lines) with aluminum alloy, domestic to red flag more, about 80 ~ 100 kg. Some data show that the weight of automobile can be reduced by 30% ~ 40% , the weight of engine can be reduced by 30% , and the weight of wheel can be reduced by 50% by using aluminum alloy structure instead of traditional steel structure. The use of aluminum alloy is one of the important ways to reduce the weight of automobile and to protect environment, save energy, increase speed and transport efficiency. Therefore, it is very necessary to research and develop aluminum alloy automobile. The main advantages of aluminum alloys are light weight and good heat dissipation. With the development of engine technology, valve structure has become the main design trend of engine.

Compared with two-valve engine, the cylinder head with four valves per cylinder produces more heat than that with two valves per cylinder. The best solution is to use all-aluminum alloy cylinder head. At present, not only the Piston, radiator and oil pan cylinder body of car engine are made of aluminum alloy, but also the cylinder head and crankcase are made of this material. In the present situation, it has become the main trend to replace cast iron with aluminum alloy in engine. French cars already have 100 per cent aluminium cylinders and 45 per cent aluminium cylinders. In the next few years, with the successful development of high strength and high quality aluminum alloy materials and continuous improvement of manufacturing technology, aluminum alloy materials will be increasingly used to manufacture such parts. Aluminum Alloy for automobile can be divided into cast aluminum alloy and wrought aluminum alloy. Casting aluminum alloy is used mostly in automobile, accounting for more than 80% , which is divided into gravity casting, low pressure casting and other special casting parts. Wrought aluminum alloys include sheet, foil, extrusion, forging and so on. Although there are some differences in the composition of aluminum alloy materials for industrial use in the world, they are basically the same. Its variety composition: casting about 80% , forgings 1% ~ 3% , the rest for processing materials. The percentage of wrought aluminum alloy in American automobile industry is 36% .

1.Application of cast aluminum alloy

The cast aluminum alloy has excellent casting properties. The suitable alloy and casting method can be selected according to the requirement of use purpose, part shape, dimension precision, quantity, quality standard, mechanical property and economic benefit. Casting aluminum alloy is mainly used for casting engine cylinder block, Clutch Housing, rear axle housing, steering housing, transmission, valve train, oil pump, water pump, rocker cover, wheels, engine frame, brake Caliper, cylinder and brake disc, etc. 

1.1 Aluminium Alloy for engines

The light weight of aluminum alloy used in automobile engine is the most obvious, which can reduce the weight by more than 30% in general. In addition, the cylinder block and the cylinder head of the engine both require good thermal conductivity and strong corrosion resistance of the material, and Aluminum Alloy has very outstanding superiority in these aspects, therefore each automobile factory carries on the engine aluminum material in succession the research and the development. At present, many foreign automobile companies have adopted the all-aluminum engine cylinder block and cylinder head. For example, the General Motors has adopted all aluminum cylinder liners; French car companies have achieved 100% aluminum cylinder liners and 45% aluminum cylinder bodies; Nissan's VQ and Toyota's Lexus IMZ-FEV6 both use cast aluminum engine oil sumps; Chrysler's new V6 engine block and head are made of aluminum alloy.

Volkswagen's advanced 6.0 l W12 engine is made mostly of aluminum and magnesium, and Audi's A8l 6.0 quattro sedan, which has a W12 engine, has been reduced to 1,980 kg, less than all other models. The W12 has a 450 horsepower, 560 NM engine, which puts it at 4.7 kg per horsepower, comparable to a high performance sports car. The Polaris series is GM's top engine after the LS series, and is the first overhead Camshaft v 8 aluminum engine in the United States. Its cylinder liner is made of Aluminum Alloy by die-casting. The 4.6 liter engines currently used in cadillacs have a maximum power of 320 horsepower and a maximum torque of 427 nm. The supercharger for the High Performance v series can reach up to 476hp/606Nm.

1.2 aluminum alloy for wheels

The aluminum wheel hub gradually replaced the steel wheel hub because of its light weight, good heat dissipation and good appearance. In the past 10 years, the global growth rate of aluminum alloy wheel is 7.6% annually, according to the analysis, by 2010, the rate of aluminum alloy wheel can reach 72% ~ 78% . A365 is a kind of casting aluminum alloy, it has good casting performance and high comprehensive mechanical properties, the world's casting aluminum alloy wheel is produced by this alloy. A6061 aluminum alloy wheel was developed by southwest aluminum processing plant of China and Light Metal Corporation of Japan. Aluminum wheels, which are widely used in automobiles, are an example of the use of aluminum in automobiles, and are used in almost all new models.

1.3 application of wrought aluminium alloy

The wrought aluminum alloy is mainly used in automobile body panel, bumper, engine cover, wheel spoke, wheel hub cover, wheel outer cover, protective cover of brake assembly, Muffler Cover, Anti-lock braking system, heat exchanger, body frame, seat, chassis bottom plate and other structural components such as instrument panel.

1.3.1 aluminium alloy for body panels

The application proportion of sheet metal in car is increasing, such as 6000 series (AI-Mg-Si series) aluminum alloy sheet after heat treatment (such as: T4, T6, T8) , can well meet the requirements of car shell, can be used as body frame material. The body of Audi A8 is made of aluminium alloy. In addition, 2000 series (AI-Cu-Mg series) , 5000 series (AI-MG series) and 7000 series (AI-Mg-zn-cu series) aluminum alloys can also be used in body materials. In recent years, using 6000-series and 7000-series high-strength aluminum alloys, thin plates and hollow sections with the shapes of "mouth" , "day" , "Eye" and "field" have been developed, which not only have light weight, high strength, good crack resistance, but also good formability, it is widely used in automobile.

1.3.2 other aluminium alloy structural parts

Aluminum is also widely used in other parts of the car, such as the 7021 aluminum plate used by General Motors to make the SMURE car bumper reinforcement bracket, and the 7021 aluminum plate used by Ford to make the Lincoln Town car bumper reinforcement bracket. The aluminum alloy material is also used in the automobile suspension parts, which effectively reduces the quality of the corresponding parts and improves the smoothness and stability of the automobile, such as the Disc brake and power transmission frame produced by 6061 forgings. In addition, aluminum alloy is also widely used in automotive air conditioning systems, such as Japan with 6595 aluminum alloy car radiator and refrigerator radiator.

2.Application of new type aluminum alloy in automobile

2.1 rapidly solidified aluminum alloy

Under the condition of rapid solidification (cooling rate of 104 ~ 109 °c/s) , the material will cause some new structural characteristics: ultra-fine microstructure, increasing the solid solubility limit of the alloy, high homogeneity, little or no segregation of the components; A new metastable equality is formed. Based on these characteristics, rapid solidification of aluminum alloy is bound to be applied in the automotive industry. In Sumitomo Electric Appliance Company, rapid solidification PM AI-Si-X high silicon aluminum alloy was used to replace sintered steel, and the rotor and blade of automobile air-conditioning compressor were manufactured in large quantities, which reduced the weight of the rotor by 60% and the whole compressor by 40% Yamaha's rapidly solidified high silicon aluminum alloy pistons are also on the market, with a 20% reduction in weight and a 30% increase in service life compared to cast iron, as well as a significant reduction in noise and pollution Mazda Automobile Company has made a new type of engine rotor by spray deposition Al-Si-Fe-Cu-Mg alloy, which can improve the engine efficiency and save fuel by 20% .

2.2 Aluminum Matrix composites

Using Ceramic Fiber, whisker and particle as reinforcing materials, we can produce aluminum matrix composites, whose specific strength, specific elastic modulus, heat resistance and wear resistance have been greatly improved, which can be used as engine parts, for example, the Al-Si Alloy Piston reinforced by al-2o 3 or SIC particles (whiskers) , which has been successfully developed by the Powder metallurgy method, can further improve the strength, wear resistance, heat resistance and fatigue resistance of the Piston while retaining the advantages of Al-Si alloy piston, in addition, the particle reinforced aluminum matrix composites can also be used to manufacture automobile engine parts such as cylinder block, Piston and connecting Rod.

2.3 aluminum foam

Foamed aluminum alloy is a kind of porous material with numerous bubbles distributed in the Metal Matrix, which has lighter weight, higher strength-weight ratio, higher energy absorption, higher damping and vibration absorption properties. Sandwich panels filled with aluminum foam between two high-strength exterior panels improve stiffness, weight and insulation when used on body roof panels, and on bumpers, longitudinal beams, and some strut parts, can increase the impact energy absorption capacity, in the lightweight, while improving the impact safety.

3.The development prospect of aluminum alloy in automobile

Although the density of magnesium alloy is smaller than that of aluminum alloy, the cost of Magnesium Ingot is higher, and there are many technical obstacles in the process of parts manufacturing, such as lack of high temperature die casting alloy and design data, poor surface treatment technology, low level of combination, etc. , therefore, the use of titanium alloy in automobile is very limited at present, and although the titanium alloy used in aerospace has high mechanical strength, the manufacturing process is difficult and the manufacturing cost is expensive, which causes the titanium alloy can not be used in automobile production in large quantities. Aluminum Alloy is the first choice of light metal materials in the automobile industry in the future because of its excellent comprehensive properties such as cost, manufacturing technology, mechanical properties and Sustainable Development (the most aluminum in the earth's crust is 8.1%) .

From the above table, every use of 1 kg aluminum can reduce the weight of 2.25 kg, weight reduction effect as high as 125% , in the vehicle life cycle can reduce emissions 20 kg. In addition, aluminum recovery is simple, except for steel can be maximum from the above table, every car use 1 kg aluminum, can reduce the weight of 2.25 kg, weight loss effect of up to 125% , the exhaust gas emission can be reduced by 20 kg in the whole life cycle of the automobile. In addition, aluminum is easy to recover, except steel can maximize the recycling of materials, almost 90% of automotive aluminum can be recovered and recycled. Aluminum has good physical and chemical properties, and the casting, forging and punching processes can be used in industrial production. It is one of the few metal materials that can be used to make parts by various casting processes. But aluminium alloys still cost more than steel. Almost 90% of automotive aluminum can be recovered and recycled from recycled materials. Aluminum has good physical and chemical properties, and the casting, forging and punching processes can be used in industrial production. It is one of the few metal materials that can be used to make parts by various casting processes. But aluminium alloys still cost more than steel. The weight of the car body is about 30% of the total weight of the car, so the lightweight of the car body occupies a pivotal position. Using aluminum alloy plate instead of steel plate on the inner and Outer Plate of automobile can reduce the body weight by about 40%-50% , if using aluminum alloy cover to reduce the body weight by 10%-15% , the effect of using aluminum alloy body plate is very significant. Aluminum Alloy in automotive lightweight applications provides a very good foundation and market prospects for the application of aluminum alloy automotive panels will bring greater opportunities. Therefore, using aluminum alloy plate instead of steel plate to make automobile body panel is also the inevitable way of vehicle lightweight. The whole body of German Audi A8 is made of aluminum, the frame is made of three-dimensional frame, and the panel is made of aluminum sheet. The aluminum body is 30-50% lighter and uses 5-8% less fuel than the steel body.

At present, China's car production after the United States, Japan, Germany, ranked fourth in the world. However, the technology of aluminizing rate is relatively backward in China. At present, the use of aluminum on automobile in developed countries has reached 138 kg, and the aluminizing rate is 12% . However, the use of aluminum on automobile in our country is far from that in foreign countries, the average amount of aluminum used is only 60 kg, and the aluminizing rate is less than 5% . Therefore, the development prospect of automotive aluminum alloy market in China is very broad.

4.Main Obstacles to the application of aluminum alloy

Expanding the use of aluminum alloys in automobiles will bring enormous economic and social benefits, however, the following problems need to be solved urgently: 

(1) the properties of aluminum alloy sheets need to be improved;

 (2) the database of aluminum alloy used in automobiles needs to be established; 

(3) the design method for developing aluminum alloy parts, the structural calculation method, 

(4) the computer simulation of the forming process and the welding process method

 (5) the study of the surface morphology of aluminum alloy materials, the pre-treatment before painting, the anti-corrosion effect after painting,

 (6) etc. , the accumulated data can provide the basis for the establishment of the process of aluminum alloy application 

(7) there is no experience and method in the maintenance market for the restoration, restoration principle and repair welding of the aluminum alloy structure and cover parts after collision, etc. 

 Source: First Die Casting

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