The hottest lightweight materials for automobiles

Automobile lightweight materials meet new challenges

2013 is the last year of the implementation period of the integrated application project of automobile key lightweight technology development and vehicle, and some key technologies of automobile lightweight are expected to be popularized and applied. A few days ago, the national automobile lightweight technology innovation strategic alliance held a promotion meeting for the integrated application project of the development of key lightweight technologies and complete vehicles in the national 12th Five Year Plan for science and technology support. According to the participants, at present, China has basically broken through the key technologies of automobile lightweight, such as body lightweight design technology and evaluation method, stamping hot forming technology of ultra-high strength steel parts, advanced forming technology of high strength steel parts, modular design and application technology of fiber reinforced plastic, development of deformed aluminum alloy parts, and integrated application of a variety of lightweight technologies aimed at vehicle weight reduction

new materials continue to emerge

Wang Zhiwen, Deputy Secretary General of the national automotive lightweight technology innovation strategic alliance, believes that cars are not the heavier the car, the safer it is. Even if very light materials are used in cars, if high-strength processing technology is adopted, the effect of very good elasticity can be achieved, and the more safe it is. In recent decades, automotive steel plates have become thinner and thinner, and the strength and corrosion resistance of steel have also been greatly enhanced. The car body is welded together by steel plates of different strength. Steel plates of different strength grades are used in different positions in the stress environment. For safety reasons, high-strength steel is mostly used in some places where the stress conditions are relatively harsh and thick steel plates cannot be used (such as crash beams and some reinforced parts)

however, the improvement of material strength also brings some problems, mainly the difficulty of processing. Generally, cars are made by stamping, that is, extruding materials with dies. The strength enhancement of vehicle steel plate puts forward higher requirements for stamping process, and now there are many deep drawing parts, and the materials are prone to cracks and wrinkles. In order to avoid the above situation, manufacturers should study the deformation of the steel plate during stamping to prevent the steel plate from tearing during stamping. However, the better the strength of the steel plate, the more difficult it is to punch

in order to fundamentally solve the stamping problem of high-strength steel, a new type of steel is applied to the production of automobile body. The matrix of this steel is relatively soft and ductile ferrite, which is embedded with martensite with good hardness. It is easy to form when stamping, and has considerable strength after forming. Therefore, this new type of automotive steel will make the car more secure when the left and right gap of the connecting part is greater than 0.5mm

at present, the plastic extruder Market in China has made great progress and breakthroughs, and the thickness of steel plate has been reduced to 0.6mm. Analyst Luo Baihui said that this may have reached the limit of steel plate thickness. No matter how thin the steel plate is, even if its own strength is high, it will also lose the structural stability of many materials themselves. At present, vehicle steel plates are challenged by new materials. From the initial power components using silicon controlled rectifier for phase-shifting trigger control to today's use of a variety of power modules to achieve pulse width modulation control war is becoming larger and larger. The atomic weight of iron determines that its density cannot be changed, and the road of weight reduction through thinning seems to have come to an end

it is understood that the national automobile lightweight technology innovation strategic alliance is cooperating with Chang'an Automobile Group to jointly develop and promote the bonnet with aluminum instead of steel. According to Wang Zhiwen, this study is based on the consideration of protecting pedestrian safety in the event of an accident. Because the application of aluminum alloy in the hood and other parts can reduce the secondary injury caused by impact. Although the weight of aluminum plate is about 1/3 of that of steel plate, its absorbed collision energy is twice that of steel plate. Aluminum alloy has a higher safety factor when encountering impact, because its material has a very good energy absorption effect. Now aluminum alloy is gradually being widely used in high-end vehicles. All aluminum SUVs have appeared, and high-end vehicles with aluminum front structure are also being followed by the industry

for some steel enterprises, automotive steel accounts for about 1/3 of the current product sales. In order to ensure the market of automotive steel and deal with the impact of new materials, many steel enterprises are actively cooperating with automotive enterprises to develop a new generation of lightweight high-strength steel, hoping to compete with aluminum alloy, plastic and carbon fiber composites

composite materials still need time

according to the data of the American Society of chemical industry, the total weight of automotive plastic parts is less than 1/10 of the total weight of automobiles. Therefore, there is still a very broad space for expansion and application. The only disadvantage of composites is poor flame retardancy, but it can be improved by adding flame retardant materials. In recent years, in order to enhance their competitive advantage in the market, car companies have developed and launched models with lightweight design. Because the sprue solidifies before the end of pressure maintaining, the shrinkage of plastic parts increases. BMW will mass produce bmwi3 pure electric vehicles in the autumn of this year. The biggest feature of this vehicle is that the shell material is plastic and the chassis material is aluminum alloy. Compared with traditional similar models, the weight of this vehicle is reduced by 250 kg ~ 350 kg

among the local car companies, Great Wall Motors Co., Ltd. and Chery Automobile Co., Ltd. are the two car companies that have gone the furthest in this research field. Chery's a3cc coupe front fender is made of norylgtx resin. At the 2012 Beijing auto show, the seven window components of the Haval e concept car on display at great wall were made of Bayer Makrolon polycarbonate and equipped with a large panoramic sunroof. This is the first time that polycarbonate windows have been applied in such a wide range by China's local automobile manufacturers. In addition, in addition to the sedan market, the lightweight of trucks has long been put on the agenda. BAIC Foton has changed the bumpers of medium-sized and heavy-duty trucks from steel to plastic, used glass fiber reinforced plastic in some auto parts, and also replaced some steel engine parts with plastic parts

however, although foreign vehicle enterprises have become more and more mature in lightweight, China's local vehicle enterprises are still in the stage of learning or catching up. This is because the domestic composite material industry is still relatively backward, especially the high-end materials are completely monopolized and controlled by some foreign chemical manufacturers, who master the design technology of materials, analysis technology and parts design technology. Because high-end materials, such as high-strength carbon fiber materials, have been monopolized by foreign technology for a long time, resulting in high product costs, some enterprises can only give up the use of high-end materials in cars. Said zhaohonghan, Deputy Secretary General of China Unsaturated Polyester Resin Industry Association

on the sidelines of the second International Summit Forum on the application of lightweight innovative materials and molding technology for automobiles held not long ago, Jiang Dingfeng, a senior engineer of Haiyuan machinery, once told the media that his company was investigating the complete equipment market of carbon fiber auto parts. It is uncertain when the equipment will be officially launched. We still need to make some investment in technology and find a market entry point. I personally estimate that it will come out in 2017 and 2018. He said that for the time being, few enterprises in the world can mass produce carbon fiber auto parts and equipment, and BMW has just developed it. In addition, he said that only carbon fiber materials can reduce the weight of cars by 50% - 60%, while the current materials can only reduce the weight of cars by about 25%