Undoubtedly, lightweighting has become the future development trend of new energy vehicles. In October 2016, the State Power Strategy Consultant Committee and Professor Ouyang Minggao of Tsinghua University released the “Energy-saving and New Energy Vehicle Technology Roadmap” that attracted much attention. It is clear that the development of lightweight technology has risen to the national level.

Among them, the roadmap includes energy-saving vehicles including light-weight technologies, pure electric vehicles and hybrid vehicles, fuel cell vehicles, intelligent network-linked vehicles and automobile manufacturing, power battery technology, and automobile manufacturing technology. The contents are as shown in the figure below.

Related research in the field of lightweight technology has concluded that weight reduction directly means an increase in cruising range. For example, if the vehicle weight of a pure electric vehicle is reduced by 10kg, the driving mileage can be increased by 2.5km. Prof. Yang Yuansheng of the Chinese Academy of Sciences said in an interview that they also agree with this conclusion and added that the driving range of electric vehicles can be increased except for In addition to strengthening the battery and drive system, it is inseparable from the degree of lightness of the body, and the most obvious feature of the body's lightweight is the choice of materials. At present, lightweight materials used in new energy vehicles mainly include high-strength steels, aluminum alloys, magnesium alloys, and carbon fibers.

Graphic: Selection of lightweight materials

Next, Xiao Bian combed the characteristics and applications of the following lightweight materials for your reference.

1, lightweight materials - high-strength steel

The high-strength steels used in the field of new energy vehicles can be divided into ordinary high-strength steels (Conventional HSS) and advanced high-strength steels (AHSS) according to different strengthening mechanisms. The advanced high-strength steels have better ductility and meet the technological requirements. At the same time, it also has higher potential for lightweighting.

Illustration: Yield strength of high-strength steel

At present, the proportion of high-strength steels in the mainstream models of the international automobile industry has reached more than 70%, of which the use of proprietary high-strength steel has reached 45%. It is understood that China is the most commonly used country for high-strength steel applications. The proportion of bodywork used is close to 50%, and it is expected to reach as high as 60-65% in the future. However, ultra-high strength and advanced high-strength steel products lag behind, and the current use ratio is only 5%. It is expected that there will be 3 times room for improvement in the future.

Graphic: High-strength steel body

Industry experts believe that compared with aluminum and magnesium alloys, high-strength steels have obvious advantages in anti-collision performance, processing technology, and cost, and can meet the dual needs of reducing vehicle quality and improving crash safety performance, even from the perspective of cost and performance. Look, it is the best material to meet the weight reduction of the car body and improve the collision safety.

2, lightweight materials - aluminum alloy

The density of aluminum is only 1/3 of that of steel, and its thermal conductivity is more than 3 times higher than that of iron. What is worth mentioning most is that the structural design optimization of aluminum substitute steel can achieve secondary weight reduction, and the effect can be directly reduced by 50%-100%. Relevant studies have shown that using 1 kg of aluminum in a car can replace 2.25 kg of steel with a weight of up to 125%, reducing exhaust emissions by 20 kg over the entire service life. It can be seen that aluminum alloys become the preferred material for vehicle weight reduction due to its high strength, recyclability, corrosion resistance, and low density. The use of aluminum in automobiles will grow rapidly, and automotive aluminum will enter the golden age.

The domestic car companies in the application of aluminum alloy materials, they have to mention Chery new energy, the company launched a new generation of pure electric mini-car - small ants (code eQ1), the structure of the use of "all aluminum space structure + full The combination of the composite outer cover "good control of the weight of the body, lower manufacturing costs, and achieve better body weight.

Graphic: Small Ant

Graphic: Full aluminum frame + composite outer cover

However, the lack of all aluminum body can not be underestimated, when the body is damaged by collision, aluminum alloy material is difficult to reshape, once the operation is not properly, parts are likely to crack or even fracture, after the general aluminum alloy parts are damaged, if The gold process can't be adjusted properly. Basically it can only be replaced as a whole. In addition, aluminum alloy materials require special processes to be welded. Therefore, the all-aluminum body means that the cost of later maintenance may be higher.

As the pioneer of the world's pure electric vehicles, Tesla has already begun exploring on the road to lightweighting automobiles. The body of its iconic Model S uses a lot of aluminum alloys, and through special welding techniques, aluminum alloy components and steel components are linked.

Icon: Tesla Model 3 Aluminum Body