Magnesium alloy performance and advantages
The density of die-cast magnesium alloy is only 2/3 of aluminum alloy and one-quarter of steel. The specific strength and specific stiffness are better than steel and aluminum alloy, far higher than that of engineering plastic, so die-casting magnesium alloy is an excellent Lightweight structural materials that can compete with the above materials in many applications.
Vibration absorption is good
For vibration and noise reduction, for example, at a stress level of 35 MPa, the magnesium alloy AZ91D has an attenuation coefficient of 25% and the aluminum alloy A380 is only 1%. At 100 MPa stress levels, AZ91D, AM60 and AS41 magnesium alloys are 53%, 72% and 70% respectively, while aluminum alloy A380 is only 4%.
High dimensional stability
The magnesium alloy die-casting due to changes in ambient temperature and time caused by the size of the unstable decrease.
High thermal conductivity
Magnesium alloy thermal conductivity (60 - 70W / m-1 K-1), second only to aluminum (about 100 - 70W m-1K-1), so good thermal diffusivity.
Non-magnetic, can be used for electromagnetic shielding.
Good wear resistance
Magnesium alloy also has a good damping coefficient, damping than aluminum and cast iron, the shell can reduce noise for the seat, the hub can reduce vibration and improve the car's safety and comfort. Magnesium alloy is light weight, strong shock absorption performance, good casting performance, high automatization and mold life, dimensional stability, as a drunk light engineering material, magnesium alloy is not only suitable for casting auto parts materials, but also drunk effective light Quantitative materials.
Magnesium alloy automotive die casting industry status quo
Lightweight development of the car, so that the demand for magnesium alloy and other light alloy castings increased year by year. Since 1990, magnesium for automobiles has been growing rapidly at an average annual rate of 20%. Magnesium alloys have become an important area for the development of automotive materials technology. Die-cast magnesium alloy with its recyclability and less no cutting technology, advanced, especially for circular economy and energy-saving low-carbon and cleaner production requirements in the car to the development of lightweight process dominates. Major auto parts manufacturers to actively grasp the timing of development, have invested in magnesium alloy automotive die-casting production R & D to. According to the "China magnesium alloy automotive die casting industry analysis report" data show that in 2015, China magnesium alloy automotive die casting industry demand reached 14.9 million tons, an increase of 23.12%. At present, the domestic and foreign automobile enterprises are devoted to studying the body parts (about 30%), engine (about 18%), transmission system (about 15%), walking system (about 16%) and wheels 5%) and other magnesium alloy or steel parts.
According to the amount of bicycle magnesium alloy used in our country, the market capacity of magnesium alloy automotive die-casting industry in our country will reach 229,000 tons by 2017, and the market capacity will reach 660,000 tons by 2022, with an average annual compound growth rate of 23.5%.
The global low volume of magnesium for motorcycles, magnesium alloy automotive demand expansion potential. For a long time, lightweight materials such as high-strength steel, aluminum alloy and engineering plastic have been widely used in various fields of automobile and auto parts manufacturing. Magnesium alloy has not been widely promoted and used for various reasons. Magnesium alloy is mainly used in dashboard Bracket, Steering Bracket, Engine Cover, Steering Wheel, Seat Bracket, Interior Door, Transmission Case, etc. At present, each car in North America uses 3.8kg of magnesium alloy and 9.3kg in Japan. Each PASSAT and Audi A4 in Europe uses 14kg of magnesium alloy per car, while the average domestic car consumes only 1.5kg.
Magnesium alloy in the automotive light of the specific application
Car interior construction
Although the corrosion resistance of magnesium alloy is poor, the anticorrosion is not the main consideration for the internal structure of the automobile. Therefore, the magnesium alloy has been widely used in automobile interior construction, especially in the dashboard and steering structure. It is reported that the first magnesium alloy instrument panel props by the General Motors in 1961 die-casting production, than the same parts produced using zinc alloy die-casting save 4 kg of material. Over the past ten years, using magnesium alloy die-casting dashboard pillar made great progress.
Magnesium alloy on the seat The application began in Germany in the 1990's, primarily with Mercedes-Benz's seat construction with SLBs using magnesium die-cast in the SL Roadster. Similar to the application of magnesium alloy on the dashboard, in recent years, the seat made of magnesium alloy has undergone a significantly improved process. Now using the magnesium alloy seat structure drunk can reach 2 mm greatly reduce the weight. Although other materials such as high-strength steel, aluminum, composites and the like are also used, experts predict that the future of magnesium alloys will be a key material for lightweight and cost-effective automotive seat components.
Magnesium alloys are limited in body applications but have also been used by OEMs. GM introduced the entire magnesium alloy die-cast roof frame when it introduced the C-5 Corvette in 1997. In addition, magnesium alloys are used in the retractable hardtop convertible roof and top frame of the Cadillac XLR Convertible. Ford F -150 Trucks and SUVs also use coated magnesium castings as a radiator support. In Europe, Volkswagen and Mercedes-Benz have pioneered the application of thin-walled magnesium alloy castings in body panels.
Currently, cast or forged magnesium alloy wheels have been used in many high-priced racing or high-performance sports cars. However, the relatively high cost and potential corrosion problems of magnesium alloy wheels prevent their use in mass production vehicles.
The future, lightweight and low-cost magnesium alloy chassis components, such as wheels, engine suspension and control arm and other parts of the production will rely on the magnesium alloy casting process greatly improved, has been developed in aluminum alloy wheels and chassis components Casting process can be successfully adapted to magnesium alloy after modification. In addition, the development of low-cost, corrosion-resistant layers and new magnesium alloys with fatigue and high impact strength will also accelerate the use of magnesium alloys on the chassis.
Most of the powertrain castings such as engine block, cylinder head, gearbox, oil pan, etc. are made of aluminum alloy. At present, North American pickups and SUVs have magnesium alloy transmissions, and Volkswagen and Audi's magnesium alloy manual transmissions are also mass-produced in Europe and China.
At present, effective tests have been made on dynamometer tests of magnesium-enhanced engine prototypes, which means that more magnesium alloys will be used in power systems in the future.
Magnesium alloy in the promotion of the main challenges
Poor corrosion resistance, high cost and high scrap rate is the popularity of "stumbling block" magnesium alloy.
Magnesium alloy manufacturing auto parts do exist high cost of casting, reject rate is high, there are potential safety problems. Du Fangci, a consultant of China Association of Automobile Manufacturers, said that magnesium is a very lively element and its corrosion resistance is very poor. The technological capability of our country in respect of the corrosion resistance of magnesium alloy parts is somewhat worse. In addition magnesium in the process of processing, prone to combustion and explosion, there are safety issues. Production site needs strict management to ensure safety in production.
As the process of urbanization accelerates, energy becomes more and more in short supply, environmental pollution is more and more serious, and energy conservation and emission reduction have become important events concerning the national economy and the people's livelihood. Whether it is traditional cars, or emerging new energy vehicles are very lightweight body design, in order to achieve the purpose of energy saving.
Automotive magnesium alloy boom, magnesium alloy die-casting process is becoming more mature, expanding the scope of applications, large-scale magnesium alloy die-casting car parts will promote the process of lightweight car.