Steel and aluminum have their own characteristics. Whether steel or aluminum is used in automobiles, ultimately weight reduction and cost effectiveness are to be considered. With the advent of the low-carbon economy era, the lightweighting of automobiles has become an increasingly popular focus. Traditional materials and processes such as steel and aluminum are also facing challenges from new environmentally-friendly lightweight high-strength carbon fibers and thermoplastics.
For a long time, steel has been the material of choice for automobiles, accounting for about 60% of the vehicle's weight on average. However, as major automobile manufacturers meet increasingly stringent emission reduction standards, aiming to reduce weight and improve fuel efficiency, the proportion of non-steel materials such as aluminum alloys and plastics in automobiles has continued to rise, and therefore steel continues to be threatened by these alternative materials. The latest survey by foreign research company Ducker Worldwide on various types of cars in the market shows that aluminum metal's vehicle weight ratio has risen to 12%, and it continues to rise. Facing the challenge of aluminum metal, steel manufacturers and car manufacturers work closely to develop lightweight, high-strength steel, and strive to maintain the leading position of steel in the automotive market.
Lightweight is the development trend of automobiles
As the requirements for environmental protection and energy saving become more stringent, the lightweighting of automobiles has become the trend of automobile development in the world. Studies have shown that for every 10% reduction in vehicle weight, fuel consumption can be reduced by 6% to 8%, and carbon dioxide emissions can be reduced by 13%. Through the transformation of the automobile structure and the optimization of manufacturing materials, there is still room for 15% of the weight of the automobile to fall, and with the continuous development and upgrade of automobile manufacturing materials, the reduction of automobile weight will not bring hidden safety hazards.
A survey by DuckerWorldwide shows that by 2025, car manufacturers' weight reduction targets will be doubled, that is, the average weight will be reduced by 400 pounds (181.4 kg), and then the average weight of steel will decrease from about 58% to 46%.
Aluminum alloy material favored
Lightweight materials and lightweight structures are important ways and means to achieve automotive lightweighting. No matter the substitution of aluminum for traditional steel or plastic for metal, the most direct effect is weight reduction. Weight reduction is the simplest and most effective way to improve vehicle fuel economy and reduce emissions. Since the 1990s, Audi and other luxury cars started to use aluminum parts, aluminum entered the automotive industry, and after that, the amount of aluminum used in cars began to rise. More and more car manufacturers began to use aluminum to replace traditional steel in material selection. And North America and other countries have been at the forefront.
DuckerWorldwide survey results show that replacing aluminum with steel to make cars can reduce vehicle weight by 30% to 40%, engine weight by 30%, and wheel hub weight by 30%. From 2006 to 2012, the EU's light-duty aluminum alloy consumption increased by an average of 19.2 kg. Aluminium accounts for 53% of the current ultralight vehicle development plans in Europe and North America. About 30% of the car hood and 20% of the bumper are made of aluminum. This proportion will be greatly increased in the next few years. , And the proportion of steel consumption will decrease. For example, the new-generation Ford Mustang, which was launched in China a few years ago, used an aluminum metal cover and an aluminum front fender, which reduced the weight by 90 kg. 317 kg lighter, fuel economy is expected to increase by 15% to 20%. The Audi R8, A8 and Jaguar XJ all use an all-aluminum alloy body. The new generation Land Rover Range Rover creatively adopts an all-aluminum load-bearing body lightweight technology, which is 39% lighter than the previous-generation Range Rover body with steel body structure. Ducker Worldwide had predicted that by 2015, the average aluminum use per car in major European countries will increase to 180 kg, and the weight of aluminum materials in the entire car will also increase from the current 9% to 12%, and will climb to nearly 250 kg by 2025. The weight ratio of aluminum vehicles to light vehicles will be doubled to the present.
Increasingly stringent regulations on automotive carbon dioxide emissions in the United States and Europe have exacerbated the battle for steel and aluminum market share. The federal government ’s fuel economy regulations require that automotive fuel economy standards be increased to 54.5 miles per gallon (approximately 4.8 kilometers per hundred kilometers) by 2025. Fuel consumption), the European Union plans to implement mandatory car exhaust emissions of 95 grams of carbon dioxide per kilometer by 2020, which is a greater challenge for car designers, steel and aluminum manufacturers scramble to invest in research and development to meet the needs of car manufacturers Metal with efficient design and lighter weight. In addition, new energy vehicles will replace traditional fuel-powered vehicles, hybrid vehicles, fuel cell vehicles, lithium battery vehicles, Mercedes-Benz E-Cell Plus and Mercedes-Benz F-Cell electric vehicles, and new powertrain vehicles such as Honda FCX Clarity. Aluminum was selected as the main material of the car body.
The latest survey results show that so-called all-aluminum cars that use a large amount of aluminum alloy can achieve a weight reduction effect of 40%, and when combined with other auxiliary lightweighting and optimized design, can improve fuel economy by up to 18%.
Comparison of steel and aluminum costs
Aluminum alloy materials are clearly the lightweight choice for automobile manufacturers, but from a cost perspective, aluminum is obviously more expensive than steel and difficult to maintain in terms of material prices, manufacturing and processing. Data from the Massachusetts Institute of Technology in 2007 shows that aluminum is more than twice as expensive as steel in terms of raw material costs, aluminum is twice as expensive as steel in terms of processing costs, and aluminum is 20% to 30% more expensive than steel in assembly. Overall, an aluminum component is estimated to be 60% to 80% more expensive than a traditional steel component. Alcoa's automotive structural experts also say that an all-aluminum body structure of a car costs an average of 1,400 to 4,600 US dollars, a 65% premium over steel bodies, and an effective and successful automotive lightweight project needs to be sustainable for future users It is obvious that a cost increase of 60% to 80% is not a successful automotive lightweight solution.
As the main material at the beginning of automobile production, steel is constantly improving to meet the challenges of various design changes, especially the successful development of high-strength steel, which best solves the contradiction between lightweight and safety and cost. Compared with other light metals and composite materials, high-strength steel has excellent cost performance, and can use existing automotive production equipment, save investment, and is an ideal lightweight material. Therefore, from the perspective of performance and cost, the dominance of steel in the automotive market will not be shaken.
High-strength steel vs. aluminum
The increase in the use of aluminum alloys has made steel manufacturers feel pressure. For a long time, major steel mills in the world have increased their investment and worked closely with automakers to develop and develop lightweight and high-strength automotive steel plates. AHSS) has become the fastest growing among automotive materials.
In 1995, the concept of "ultra light steel body" was jointly proposed by the American Iron and Steel Association, the International Iron and Steel Association, automobile manufacturers and some steel companies. It can reduce the weight of the vehicle body by 25%, and also reduce the manufacturing cost, which provides a good solution for high-strength steel in the competition with non-steel materials such as aluminum and aluminum alloys. At present, in the automotive design schemes of European "ultra light vehicle engineering" manufacturers, the use rate of high-strength steel exceeds 80%. According to the calculation of the steel industry, the amount of steel used in automobiles has actually increased in recent years.
1.Ultra light steel car body project-ULSAB
In 1994, the World Steel Association first launched the Ultra Light Steel Auto Body Project (ULSAB), which involved 35 steel companies from 18 countries on 5 continents. The project lasted 4 years, and the main goals were to reduce body mass, increase structural strength, improve safety, simplify manufacturing processes and reduce production costs. With the goal of reducing the weight of the car body, the weight of the car body should be reduced by more than 25%, which will bring revolutionary changes to the automotive industry. Studies have confirmed that ULSAB can reduce weight by 25% without adding any cost. In recent years, European and American automobile companies have adopted some or all of the ULSAB project technology when developing new cars. High-strength steels have been used in a large number of automotive body, chassis, suspension, and steering components.
2.Ultra light steel vehicle suspension project-ULSAS
Other projects related to ULSAB are ULSAC and ULSAS. ULSAC is the application of high-strength steel to automobile body coverings, while ULSAS uses high-strength and ultra-high-strength materials and some advanced manufacturing technologies to produce light weight, cheapness and performance. Good suspension system, the goal is to reduce the weight of the suspension by 20% by adopting new steel and design. Large steel mills such as American Iron and Steel, Posco, Nippon Steel, ThyssenKrupp participated in the project. The American Iron and Steel Association's Steel Market Development Institute recently revealed that the new design of advanced high-strength steel can reduce the weight of the car's torsion beam rear suspension by 30%. Compared with other alternative materials, the cost is greatly reduced and the fuel is more economical. The ULSAS project is a good example of the use of advanced steel production technology to achieve automotive suspension weight reduction.
3.Ultra-light vehicle body-Advanced Automotive Technology Project——ULSAB-AVC
In March 1998, the World Steel Association started to implement the Ultra Light Vehicle Body-Advanced Vehicle Technology Project (ULSAB-AVC) worldwide. This project is the overall research and development of a new generation of steel material automotive structures (bodywork, covers, suspension systems, engine mounts and all structural and safety-related components), and supports the use of ultra-light steel and advanced automotive technology to support Steel is the most ideal and affordable material for the next generation of cars. In this project, the application of advanced high-strength steel (AHSS) accounts for about 80%, and more than 20% of the components adopt hydroforming technology. Studies have confirmed that the ULSAB-AVC AHSS design is 25% lighter, while meeting the collision requirements Without increasing costs.
4． Future Steel Car Project-FSV
In order to compete with other materials and maintain steel's share in automotive materials, the World Automobile Steel Federation launched the Future Steel Vehicle Project (FSV). FSV's three-year plan is: engineering research from 2008 to July 2009, concept car design from August 2009 to 2010, and hardware demonstration from 2010 to 2011. The FSV project has designed advanced high-strength steel body structures for four models such as battery electric vehicles (BEV), hybrid vehicles, plug-in hybrid electric vehicles (PHEV), and fuel cell electric vehicles (FCEV), using more than 20 advanced AHSS Steel, it is estimated that these advanced materials are expected to achieve commercial production from 2015 to 2020. The flexibility, high strength and formability of steel are best adapted to the optimization process of component shape and structural design. In addition, laser tailor-welded plates and tailor-welded tubes, Advanced processing technologies such as hydroforming. Obviously, the FSV concept car is efficient and lightweight. An FSV battery electric vehicle weighs 188 kilograms, which is more than 35% lighter than a conventional internal combustion engine car body, further reducing the weight loss gap with aluminum and magnesium alloys. In addition, it can reduce emissions by nearly 70%, which meets the stringent emission standards of battery and electric vehicle manufacturers and 2020, and also meets the requirements of crash testing and durability, without increasing costs due to weight reduction.
As the world's largest automobile production base and market, China has huge potential for the future market for lightweight vehicles, despite the current low proportion of automotive aluminum alloys in China. In 2020, in order to achieve the average fuel consumption of cars from 7.5 to 100 km and 5 litres, China needs to accelerate the development of miniaturization and light weight of cars. Some auto and component manufacturers have set their sights on auto parts. Lightweight research and development. In this tide of structural adjustment and environmental protection governance, China's iron and steel manufacturers must actively take advantage of the great opportunity of structural transformation, cooperate with automobile manufacturers to develop more advanced steel products, and maintain the main position of steel in automotive materials.