As a typical lightweight metal, aluminum alloy is widely used in foreign automobiles. Foreign automobile aluminum alloy components mainly include pistons, cylinder heads, clutch shells, oil pans, bumpers, heat exchangers, brackets, wheels, body panels and decorations. Parts etc.

At present, the United States, Japan, and Germany are the countries that use the most aluminum alloys for automobiles. For example, the Audi A8 and A2 of Volkswagen in Germany and the NXS of Japan use 80% of aluminum alloys for the body. Except for the aluminum alloy used by Shanghai Santana, FAW Audi and Jetta (all of which are imported production lines), my country's automobiles have more red flags, about 80-100kg.

Some data show that replacing the traditional steel structure with aluminum alloy structure can reduce the quality of automobiles by 30%-40%, manufacturing engines can reduce 30%, and manufacturing wheels can reduce 50%. The use of aluminum alloys is one of the important ways for automobiles to be lightweight, environmentally friendly, energy-saving, speed-up, and efficient in transportation. Therefore, research and development of aluminum alloy cars is now very necessary. The main advantages of aluminum alloy are light weight and good heat dissipation. With the development of engine technology, valve structure has become the mainstream design trend of engines.

Compared with a two-valve engine, a cylinder head with four valves per cylinder generates more heat than a cylinder head with two valves per cylinder. Using an all-aluminum alloy cylinder head is the best solution. At present, not only the piston, radiator, oil pan and cylinder block of car engine parts are made of aluminum alloy, but also the cylinder head and crankshaft

The box also uses this material. Under the current situation, it has become a mainstream trend to use aluminum alloy instead of cast iron in engines. The aluminum cylinder liner of French cars has reached 100%, and the aluminum cylinder block has reached 45%. In the next few years, with the successful development of high-strength and high-quality aluminum alloy materials and the continuous improvement of manufacturing processes, aluminum alloy materials will be more and more used to manufacture this type of parts. Aluminum alloys for automobiles can be divided into cast aluminum alloys and deformed aluminum alloys.

Cast aluminum alloys are the most used in automobiles, accounting for more than 80%, which are divided into gravity castings, low-pressure castings and other special casting parts. Deformed aluminum alloys include plates, foils, extruded materials, forgings, etc. Although there are certain differences in the variety and composition of industrial aluminum alloy materials in various countries in the world, they are generally the same. Its variety composition: castings account for about 80%, forgings account for 1% to 3%, and the rest are processed materials. Wrought aluminum alloy accounts for a large proportion of the US automobile industry, reaching 36%.

1. Application of cast aluminum alloy

Cast aluminum alloy has excellent casting properties. Suitable alloys and suitable casting methods can be selected according to the requirements of the purpose of use, part shape, dimensional accuracy, quantity, quality standards, mechanical properties, etc. and economic benefits. Cast aluminum alloy is mainly used to cast engine cylinder blocks, clutch housings, rear axle housings, steering gear housings, transmissions, valve trains, oil pumps, water pumps, rocker covers, wheels, engine frames, brake calipers, cylinders and Non-engine components such as brake discs.

1.1 Aluminum alloy for engine

The aluminum alloy used in automobile engines is the most lightweight, generally reducing weight by more than 30%. In addition, the cylinder block and cylinder head of the engine require the material to have good thermal conductivity and strong corrosion resistance. Aluminum alloys are very prominent in these aspects. Therefore, various automobile manufacturers have carried out research and development of engine aluminum materialization. At present, many foreign automobile companies have adopted all-aluminum engine cylinder blocks and cylinder heads. For example, General Motors Corporation of the United States has adopted all-aluminum cylinder liners; French automobile company’s aluminum cylinder liners have reached 100% and aluminum cylinder blocks have reached 45%; Japanese Nissan’s VQ and Toyota’s Lexus IMZ-FEV6 have adopted cast aluminum engine oil. Bottom shell; Chrysler's new V6 engine cylinder block and cylinder head are made of aluminum alloy materials.

National Volkswagen’s advanced 6.0L W12 engine is basically made of aluminum-magnesium alloy. Due to the W12 engine used on the Audi A8L 6.0 quattro sedan, the weight of the vehicle is reduced to 1980kg, which is lower than all other models. The W12 engine has 450 horsepower and 560Nm of strong power, so that its unit horsepower needs to accelerate the weight of only 4.7kg, which is comparable to high-performance sports cars.

The Polaris series engine is GM's top-of-the-line engine except for the LS engine series. It is the first V8 aluminum alloy engine with overhead camshafts in the United States. Its cylinder liner is made of all aluminum alloy die-casting. The 4.6-liter engine currently widely used in Cadillac has a maximum power of 320 horsepower and a maximum torque of 427Nm. The supercharged version applied to the high-performance V series can even reach 476 horsepower/606Nm.

1.2 Aluminum alloy for wheel hub

Aluminum wheels are gradually replacing steel wheels because of their light weight, good heat dissipation, and good appearance. In the past 10 years, the global aluminum alloy automobile wheels have grown at an annual growth rate of 7.6%. According to analysis, by 2010, the aluminization rate of automobile wheels will reach 72% to 78%. A365 is a cast aluminum alloy. It has good casting properties and high comprehensive mechanical properties. Cast aluminum alloy wheels all over the world are produced by this type of alloy. The Southwest Aluminum Processing Plant of my country and Japan Light Metal Co., Ltd. jointly developed A6061 aluminum alloy wheels. Aluminum wheels widely used in automobiles are an example of the application of aluminum alloy in automobiles. Almost all new models use aluminum alloy wheels.
Second, the application of new aluminum alloys in automobiles

2.1 Rapid solidification aluminum alloy


Under the condition of rapid solidification (cold rate up to 104～109℃/S), the material will cause some new features in the structure: ultra-fine microstructure; increase the solid solubility limit of the alloy; highly uniform composition, less segregation or no Segregation; forming a new metastable equal.



Based on these characteristics, rapid solidification aluminum alloys will inevitably be used in the automotive industry. Sumitomo Electric Company uses rapid solidification PM AI-Si-X high-silicon aluminum alloy instead of sintered steel to manufacture automobile air-conditioning compressor rotors and blades in large quantities, reducing the weight of the rotor by 60% and the weight of the entire compressor by 40%;



The rapid solidification high-silicon aluminum alloy piston produced by Yamaha Motor Manufacturing Company is also put on the market. Compared with ordinary cast iron, this piston has a weight reduction of 20%, a life span of 30%, and significantly reduces noise and pollution; Mazda Motor Company A new type of engine rotor is made by spray deposition of Al-Si-Fe-Cu-Mg alloy, which improves engine efficiency and can save fuel by 20%.


2.2 Aluminum matrix composite material


Ceramic fiber, whiskers, particles, etc. are used as reinforcing materials to produce aluminum-based composite materials. The specific strength, specific elastic modulus, heat resistance, wear resistance, etc. are greatly improved, and they can be used as engine parts, such as powder metallurgy. The successfully developed Al-Si alloy piston reinforced by Al2O3 or SiC particles (whiskers) can further improve the strength, wear resistance, heat resistance and fatigue resistance of the piston while retaining the advantages of the Al-Si alloy piston. Used in automobile engines; in addition, particle-reinforced aluminum-based composite materials can also be used to make parts such as cylinder blocks, pistons and connecting rods of vehicle engines.

2.3  Aluminum alloy foam

Foamed aluminum alloy is a porous material with numerous bubbles distributed in the metal matrix. This material is lighter in weight, higher in strength-to-weight ratio, and has high energy absorption characteristics, high damping characteristics and vibration absorption characteristics. The sandwich panel made by filling foam aluminum between two high-strength outer panels can increase rigidity, lighten weight and improve thermal insulation performance when used in car body roof panels. It is used in bumpers, longitudinal beams and some pillar parts. It can increase the impact energy absorption ability when it is up, and it improves the impact safety while reducing the weight.

Third, the development prospects of aluminum alloy in automobiles

Among the lightweight metals, 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 parts manufacturing process, such as lack of high-temperature die-casting alloy and design data, poor surface treatment technology, and low level of bonding Therefore, the current usage in automobiles is quite limited; while titanium alloys used in aerospace have high mechanical strength, but the manufacturing process is difficult and the manufacturing cost is expensive, which makes titanium alloys unable to be used in automobile production in large quantities. Aluminum alloy has good comprehensive performance in terms of cost, manufacturing technology, mechanical properties, sustainable development (the most aluminum content in the earth's crust, accounting for 8.1%), etc. Therefore, aluminum alloy is the preferred light metal material in the automotive industry now and in the future.