Analysis of magnesium alloy application technology for automobile body parts

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  New energy vehicles are new models for conventional fuel-powered vehicles, which mainly include several types, namely hydrogen energy-powered vehicles, hybrid vehicles, and solar vehicles. During the production and manufacturing of new energy vehicles, new materials are mainly used to save resources. Since 1990, magnesium alloys have begun to be used in the development of automobile parts. Magnesium for automobiles has grown year by year, and now it has gradually become an important area that cannot be ignored in automobile material technology. At this stage, the domestic and foreign automobile industries have begun to conduct research on the development of new energy automobile parts, with a view to giving full play to the advantages of magnesium alloy parts and improving the quality of new energy automobiles.

  1 Current status of new energy vehicle research

  New energy vehicles are known as "alternative fuel vehicles" and generally use clean fuels such as ethanol and compressed natural gas to replace traditional diesel and gasoline. In addition, the range of new energy fuels currently developed in the United States is also expanding, such as biodiesel, hybrid and hydrogen fuels, etc., providing new impetus for the development of new energy vehicles. The widespread application of new energy vehicles is directly related to policies introduced by government departments. For example, in 1993, the U.S. government introduced the "New Generation Automotive Partnership Program" to support the research and development of new energy vehicles. Under this policy, Effectively reduces the CO2 emissions of cars. When developing new energy vehicles, European countries focus on reducing greenhouse gas emissions and require newly developed vehicles to meet CO2 emission requirements. In the early stage of the research, biomass fuel and natural gas were mainly used. After entering the 21st century, biomass fuel, CNG, and hydrogen fuel began to replace 23% of petroleum, reducing greenhouse gas emissions. Our country's current economic level has grown significantly, the masses' rigid demand for car purchases has gradually increased, and the growth trend of car ownership is very impressive. Relevant data shows that as of December 2017, the number of civilian cars in China has exceeded 275.27 million, an increase of 16.2% compared with 2016, including 153.36 million private cars, 158.63 million civilian cars and 16224 Thousands of private cars. As the number of automobiles continues to grow, automobile energy consumption and emissions increase accordingly. In order to achieve green ecological construction, the "863 Plan" has been officially put on the agenda. Beginning in 2015, the "Thirteenth Five-Year Plan" began to be implemented, including a new energy vehicle promotion plan, hoping to improve the level of industrialization development of electric vehicles. However, because a series of research on new energy vehicles requires a large amount of funds, and researchers are limited, the industry is still in the development stage. Compared with developed countries such as Europe and the United States, there is a certain gap. In particular, the research and development of new energy vehicle parts will need to start from high-tech in the future. We will start with technology, improve relevant facilities, and accelerate the research and development of magnesium alloy parts based on the relevant preferential policies proposed by government departments, thereby improving the competitiveness of new energy vehicles.

  2 Application advantages of magnesium alloy materials in parts development

  2.1 The mass density of magnesium alloy materials is relatively small, mainly 2g/cm3. It is about 36% lighter than aluminum and about 73% lighter than zinc alloy materials. If used in the development of new energy vehicle parts, magnesium alloys will effectively reduce their mass. 2.2 Vibration-absorbing properties The damping capacity and vibration-absorbing properties of magnesium alloy materials can withstand relatively large impact vibrations. Compared with aluminum, steel and other materials, users can develop internal parts of automobiles that can withstand impact loads and vibrations, improving their operation reliability. stability. 2.3 Higher specific strength and specific stiffness If the quality conditions are consistent, then the specific stiffness of magnesium alloy is higher. The quality of magnesium alloy is lower than that of steel, aluminum alloy and other materials, and its specific strength and specific stiffness are higher. 2.4 Support for recycling: The extraction of magnesium alloy materials is mainly based on renewable resources and can be fully recycled. Because magnesium has a relatively low melting point, recycling consumes less energy.

  3 Development of magnesium alloy parts for new energy vehicles

  3.1 The application of magnesium alloy materials in the development of new energy vehicles began in the early 20th century. Germany was the country that used magnesium alloys in automobile manufacturing. By the 1950s, Volkswagen used a large number of structural parts in the production and development of Beetle cars. magnesium alloy materials. Subsequently, European and American countries also began to invest in the research and development of magnesium alloy parts. Today, North America leads the world in automotive magnesium use, followed closely by Europe. In contrast, Japan lags behind Europe and the United States. In its early days, it only used magnesium alloys to produce components such as cylinder heads and seat frames. However, with the continuous development of its technology, the application of magnesium alloy materials has become more common. For example, Toyota has specially developed a magnesium alloy steering wheel, and in recent years has launched front seats with magnesium alloy frames. In contrast, the use of magnesium alloys in my country's automobile industry was relatively late and is still in the development stage. During the research and development process, SAIC used magnesium alloy in transmission housings and clutch housings. FAW mainly used magnesium alloy as the main material for parts such as engine covers and clutch housings. Second Automobile Works in the process of developing magnesium alloy materials , gradually formed a mature R&D system and invested in a large number of magnesium alloy die-casting production lines to support the production of more automotive parts. For the application of magnesium alloys in new energy vehicles, current research and development work is more focused on power system parts. In order to meet the temperature regulations of engine parts during operation, countries in recent European and American regions have begun to develop high-strength magnesium alloy materials, such as AE, Mg-Al-Ca, etc. Nowadays, some new magnesium alloy materials have been successfully developed, such as corrosion-resistant magnesium alloys, deformed magnesium alloys, high-strength and high-toughness magnesium alloys, and flame-retardant magnesium alloys. Among them, deformed magnesium alloys are mostly used in car bodies, such as body component outer panels and car door windows, seats, chassis and body frames. 3.2 Application of magnesium alloy parts in new energy vehicles 3.2.1 Magnesium alloy dashboard frame The dashboard frame of conventional models is mostly made of welded steel parts. In order to meet the requirement of lightweight vehicles, it is necessary to ensure the original functions. On the basis of ensuring that the parts of the assembly surface and holes do not change, the instrument panel frame parts are replaced with magnesium alloy. The two processes of extrusion and bending are mainly used to make the magnesium alloy instrument panel frame. All magnesium alloy parts are connected by hydrogen arc welding. Because magnesium alloy and steel will corrode after contact with the two materials, it is recommended to use steel aluminized bolts as connectors to connect the instrument panel frame to the body, instrument panel and other components. Through practice, we learned that the weight of the lightweight magnesium alloy dashboard frame is 1.957kg, which is 62.9% lighter than the original steel parts used in conventional models. 3.2. 2 Magnesium alloy passenger seat frame The driver's seat frame of conventional models is mainly made of steel parts, which includes three parts: backrest frame, seat cushion frame and slide rail. Because there are certain restrictions on the modification of urban-sized models, in accordance with the relevant regulations on car seat design, in order to ensure the performance of the car, the chair frame of the passenger seat was replaced with magnesium alloy. There are three main manufacturing processes: extrusion, bending and stamping. The welding technology for magnesium alloy parts is hydrogen arc welding, and structural adhesive is used to connect all material parts. After practice, the mass of the magnesium alloy passenger seat frame was shown to be 12.66kg, which is 8.3% lighter than the steel structure.

  3.2.3 Magnesium alloy front and rear subframes

  In order to ensure that the technical parameters of the magnesium alloy front and rear subframes can meet the specified requirements, the original structural design needs to be improved. During the design process, the structure was designed through three requirements: wedge-shaped reinforcing ribs, longitudinal reinforcing beams at local locations, and local thickening. Finite element verification and analysis of the final design results were carried out. It can be concluded that the designed magnesium alloy front and The technical parameters of the rear subframe are consistent with the regulations. There are three main processes used in this part: extrusion, bending and shaping. Welding manufacturing is mainly based on segmented manufacturing, ring welding and fillet welding. After the welding operation is completed, the rubber lining of the support sleeve is pressed in, and bolts are used to connect the car. , and composite gaskets are set at the same time to achieve a good connection effect. After lightweight design, the mass of the magnesium alloy front and rear subframes is reduced by 50.5% and 62.3% respectively compared with steel parts. 3.2.4 Magnesium alloy rims According to the relevant regulations for magnesium alloy manufacturing, the root position of the small spokes of the rim must be dug deeply. The magnesium alloy wheels must meet the performance requirements. The stresses of bending fatigue and radial fatigue are less than the fatigue strength of magnesium alloy materials. 110MPa, with a service life of more than 107 times. Through practice, it can be seen that the weight of the magnesium alloy rim after lightweight design is reduced to 7.9kg, which is 37% lighter than the aluminum alloy wheel rim. 3.2.5 3D Printing Nowadays, the competition in the automotive industry is becoming increasingly fierce. In order to occupy a favorable position in the market, various companies have invested in the research and development of new technologies. 3D printing technology is one of many new technologies. It is an advanced technology developed based on the actual application of new car models and tools. The application principle is shown in Figure 1. The production of magnesium alloy parts through scanning mirrors, laser beams and other components effectively increases the speed of parts production. Nowadays, 3D printing technology has been popularized in automobile companies, which not only saves R&D costs, but also greatly improves R&D efficiency and can meet customers with high requirements and small batches.

  4 Development Prospects of Magnesium Alloy Parts for New Energy Vehicles

  Nowadays, with the improvement of environmental protection concepts, the research and development of green technologies and products has become key. Magnesium alloy is a hot green material in the new environment and a hot topic in industrial research. At present, in the process of researching the structure of new energy vehicles in our country, we have gradually clarified the main direction of future industry development, namely, low emissions, low pollution, and achieving energy conservation and environmental protection. Under this goal, the development speed of magnesium alloy materials will continue to increase in the future. It is expected that the consumption of magnesium materials in European and American countries will continue to grow for a period of time. Worldwide, Asia and Europe are the regions with the fastest growth rate of magnesium material consumption, especially Asia. At present, the growth rate of magnesium materials in my country exceeds 30%, and it is expected to become the region in Asia and even the world. Based on the development of the new energy automobile industry, the die-casting industry is the core growth point of magnesium materials. If its average annual growth rate is 10%, the consumption of magnesium materials will increase significantly by 2020.

  In summary, the development and application of magnesium alloy parts in new energy vehicles represents the innovation and upgrading of the automotive industry. It also clears the direction for future industry development. It is necessary to conduct in-depth research on new materials including magnesium alloys to reduce the burden of automobiles. quality and improve automobile performance, thus promoting the rapid and stable development of my country's automobile industry.