On September 20-21, the "2019 (Seventh) Automotive and Environmental Innovation Forum", sponsored by the National Specially Appointed Automotive Group and Gas Automotive, was held under the guidance of the Automotive Talent Professional Committee of the China Talent Research Association. In the form of four parallel forums, with hundreds of industry authoritative guests, together to discuss the new situation and new normal of the transformation and upgrading of the Chinese automobile industry, OEMs and component companies will collaborate to innovate, upgrade and strengthen, and jointly respond to severe market and industrial changes Challenge development path. The following is the speech of Xiong Ziliu, chief engineer of Hegang Iron and Steel Research Institute:
Lightweight, Automotive and Environment, Xiong Ziliu, Hegang, Lightweight Automotive
Xiong Ziliu, Chief Engineer, Steel Research Institute, Hesteel Group
Hello everyone, first of all, thank you for such a discussion of technical experts in the entire industry chain. Hesteel is mainly a steel supplier. We focus on materials and material application technology. Today my topic is mainly Hesteel Group's automotive steel products and lightweight application technology.
My report today is mainly divided into 5 parts. First, the first part is an overview of automobile steel for Hesteel Group. Hesteel Group was established in 2008. The entire headquarters is in Shijiazhuang. There are more than 20 subsidiaries. The holding companies are There are more than 70 companies. The main iron and steel industries are Tang, Han, Xuan, Wu, Mining and so on. They have entered the Fortune 500 for 11 consecutive years. Our current world ranking is 214.
According to the 13th Five-Year Plan of the Hebei Iron and Steel Group, automobile steel is our strategic product. The production base also includes 5 production bases in Tangshan, Handan, Xuanhua, Chengde, and Shijiazhuang. There are more than 30 main production lines, including hot rolling, Production lines for cold rolling, aluminum-silicon coating, etc. Our main supply OEMs are located in more than 100 factories around the world.
Our products have achieved very great development. In 2010, the output of automotive steel was 300,000 tons, which exceeded 7.25 million tons in 2018, ranking second in China. The entire product composition, including cold-rolled hot-dip galvanizing, is more than 2 million tons. Hot rolling is more than 3 million tons, and there is more than 1 million tons of special steel.
We have established a global product research and development platform, and cooperated with customer cooperation research and development centers to carry out research and development cooperation to achieve a win-win situation. The research and development platform is divided into several levels. The first is the internal research and development platform of the group. It has two industrial technology research institutes, including Hegang Steel Research and Mechanical Research Institute, to solve the research on common aspects of products and applied technologies, in addition to three national technology centers and five provincial technical research centers to solve practical problems related to product and application technology of the production line, and 8 National key laboratories solve some product performance and technology-related issues in product testing and certification. In addition, we began to establish customer R & D centers with customers from 2016, and established a scientific research cooperation agency with a common destiny with customers. Product development and application technology research started to carry out EVI cooperation. So far we have signed 5 customer R & D centers with Haier and Guoneng Automobile.
Domestic R & D platform, we cooperate with more than 10 universities and colleges of science and technology of Northeast University, Beijing University of Science and Technology, Chongqing University, and Tianjin Automotive Engineering Research Institute to conduct product and process technology research and development. We work with foreign steel institutes, the World Automobile Steel Federation, and other foreign scientific research institutions such as the University of Queensland, MEFOS, etc. to develop common and sustainable technologies and product application technologies for green. I am a member of the Alliance. I participate in the meetings of the Alliance twice a year, and some technical content comes from common research reports. In addition, Hesteel Group was the rotating chairman of the Steel Association last year and the rotating chairman of the International Steel Association this year. It has carried out research and development of clean steel with MEFOS. The University of Queensland has cooperated with the high-strength steel forming application technology. At present, it is the world's top forming technology. Make a corresponding introduction.
Cold-rolled and coated products, from the first generation of automotive steel to the third generation of automotive steel, all grades are covered, and the strength of hot-formed steel from the lowest 100 MPa to the highest 2000 MPa, to achieve the entire vehicle construction. This is our automotive steel market. Our auto sheet has completed the certification of BMW Germany this year. Now it is certified by Volkswagen, GM and Ford. The main auto suppliers are BAIC New Energy, SAIC, Great Wall, Haima, etc. More than 10 OEMs, special steel, users are relatively more high-end, Mercedes-Benz, BMW, Chrysler and other more than 100 OEMs around the world and more than 1,000 spare parts factories for supply.
The second part introduces the lightweight technology roadmap of Hesteel Group. First, we briefly review the technical background. Everyone has heard cocoons about the energy conservation and environmental protection of automobiles. This concept was proposed by the United States. The FSV models developed in the 1990s, because the energy consumption of American cars is the largest, and the entire automobile consumes about 60% of the oil. Therefore, the FSV project was proposed to solve the problems of automobile oil consumption and exhaust emissions. Xiehe Automobile Steel Alliance has been researching and developing this project.
Regarding carbon emissions, we need to consider the raw material production, transportation, parts and vehicle manufacturing, vehicle consumption stages, and the entire life cycle stages of vehicle retirement and recycling. It is the issue that we should focus on extending the concept of carbon emissions to the entire industrial chain. At present, considering only the fuel consumption and carbon emissions at the consumption stage may actually be misleading for the development of our cars. From the perspective of carbon emissions throughout the life cycle, in fact we now think that the lightweighting effect of lightweight alloys, aluminum alloys, and magnesium alloys is very good, but from our current research point of view, the full life cycle of steel Carbon emissions are much lower than aluminum, magnesium alloys, and carbon fibers. You can refer to some experimental reports related to the World Automobile Steel Federation. I think that the concept of LCA in the whole life cycle will be introduced to the concept of automotive design. Now some OEMs, such as Toyota, have used LCA to design. How much steel is used? How much is used for aluminum alloy magnesium alloy? Adding up the total life cycle carbon emissions will be a selling point for car companies. Carbon emissions are no longer something everyone talks about. To move the truth, let's look at China's 2020 target of 93 grams and Europe's 50 grams.
Last year, a standard for life-cycle greenhouse gas emissions was issued. This standard will be a policy that stipulates how much carbon emissions must be achieved in cars. This policy is likely to be implemented in the near future.
The weight reduction path of Hesteel is mainly to use the right materials in the right places. The weight reduction method adopted by Hesteel is the high-strength steel. Why? I will have a detailed introduction later in the PPT. In addition, the process of lightweighting is still tailored welding, cold forming, hot forming, rolling, etc. The lightweighting includes structural lightweighting, lightweight frame, and lightweight boundary. We work with some cooperative customers to conduct research.
Why do we choose high-strength steel as the main material for lightweight? First of all, aluminum alloy and magnesium alloy, we have compared the average door weight of more than 400 models. Let ’s take a look at the fact that aluminum alloy has a light weight effect compared to steel, which can reduce weight by about 5.73 grams. This is the structural design. We design it as a car door, because the door is not only a structure, there will be some fillers and other parts, because the vibration performance and the steel degree are considered, and because we know that the steel degree of aluminum is relatively low, the stuffed things will More.
After making the door, look at the effect of lightening. Let's look at the following pictures. Aluminum is only 0.45 kg lighter than steel. This is an average result. Let's look at the right side, which shows the effect of a structural design, which is good. As a result of statistics of hundreds of models, if steel has a reasonable structural design, this lightweight effect can be comparable to aluminum, that is to say, in fact, steel has a great potential to achieve lightweight structural design. .
In addition, from the perspective of cost, this is a comparison of the auxiliary frame. If aluminum is replaced with high-strength steel, the weight reduction ratio is about 0.66, and the weight reduction cost increases by 49.2 yuan per kilogram. If it is lightweight with advanced high-strength steel, The ratio is 0.83, and the cost is increased by 54 yuan. This is an estimated price. There may be some errors in the specific situation, but the overall situation is that the weight of steel is much lower than that of aluminum alloy.
In the third direction, I would like to introduce the main solutions for material lightweighting of Hegang, mainly in the material development phase. There are three stages. The first phase is to reduce the weight by increasing the strength and thinning. We all know that increasing strength will sacrifice toughness and elongation and performance. We have many problems during the use of users. We develop steels that meet specific forming processes based on the problems that arise, such as high hole expansion performance and shear cracking resistance. And meet the requirements of hot-formed steel types, but high-strength low-alloy steels, low-yield duplex steels, martensitic steels, etc. cannot meet the requirements of these specific forming processes; with the continuous increase in lightweight requirements, the former two have improved The strength method still cannot completely solve the problem of ultra-high-strength steel applications. Based on this, we have developed the second and third types of automotive steels. This strength is higher and the elongation rate will be very high. It is mainly quenched steel, TRIP and so on are all developed now.
Introduce the main types of steel for structural lightweighting. First, low-yield dual-phase steel is the most commonly used. Consumption is mainly in two categories. One is continuous retreat and the other is hot-dip galvanized. The row number includes DP450, DP500, DP590, 780DP, 980DP, the main application parts are structural parts and reinforcement parts.
The low-yield steel is relatively low, and it becomes helpless when the safety requirements are relatively high. Based on this, we have developed a high-yield duplex steel that also uses continuous withdrawal and hot-dip galvanizing. The main feature is bending The performance is better, it becomes more uniform in the two-phase structure, the hardness difference between the two phases is relatively small, so it has low bending performance, the minimum bending radius is small, and it has good resistance to shear cracking and flanging. Development of safety structures.
The reamed steels we develop are mainly hot-rolled, hot-rolled pickled, and cold-rolled, mainly 450, 580, and 780. The main application parts are suspension chassis and wheels.
The other is martensitic steel. On the cold rolling production line, we use the most advanced high hydrogen continuous dehydration quenching in China so far. The cooling rate of hydrogen injection can reach more than 100. The cooling rate can be strengthened. Purpose, because other high-strength dual-phase steels are mainly based on alloy strengthening, one is structure strengthening, and we are strengthening through structure alone, so we can achieve high strength, and the cost is relatively low, martensite Steel easily achieves 1500 MPa performance, but HSLA, DP and other steels are difficult to achieve. The main feature of the martensitic steel series is to achieve high strength, high rigidity and high reaming performance, which are mainly used on structural parts.
The third type is the continuous annealing of QP980 and QP1180. At present, 980 has some commercial applications. 1180 belongs to the stage of laboratory research and development. Now it has been experimentally tested in the industry, but it is still looking for customers. The main features are processing. It has better hardening, strong plastic product, high bending performance, and high energy absorption.
Hot-formed steel can now do HS1500, 1800, 2000 including bare and aluminum silicon plates, which are characterized by low deformation resistance, small springback, high forming accuracy, and the application parts are mainly in structural parts and suspension parts.
We know that Al-Si hot-formed steel is ArcelorMittal's patented technology. I have been researching Al-Si hot forming since 2012. I have formed my own patented technology. I have added some alloying elements to improve the high temperature oxidation resistance. These two patents have been authorized in China to improve the high-temperature corrosion resistance. Now they are applying for patents abroad, and they already have patent numbers in Europe and the Americas. Because the patent application cycle abroad is relatively long, it is estimated that they will wait for a period of time to return to grant.
What are the characteristics of our patent? We see that the highest heating temperature for aluminum-silicon forming is 850-900 degrees. Some of the alloy will also be dissolved in the aluminum phase, which will increase the melting point of the coating and ensure the forming performance. In this way, the forming performance and high-temperature oxidization will be organically unified. . We know that the aluminum-silicon coating is a thermoformed sheet and can only be indirectly thermoformed, and our patented technology can not only indirectly form, but also achieve direct forming, so this is our advantage.
Zinc-aluminum products include deep-drawing series, high-strength IF steel, structural steel, high-strength low-alloy, dual-phase steel, etc. The main features are corrosion resistance, good notch protection, welding performance, and forming performance better than GIGA. The use of automotive panels has reduced beeswax and coating performance. Baosteel has also been pushing Zn-Aluminium products and has not pushed them away. We are now also including it in promoting Zn-Aluminum products. This year we have made certain breakthroughs. OEMs started using our zinc aluminum products.
In the fourth aspect, we establish our own database of automotive panels. The current database includes the material database and the disassembly database. There are three major parts of the material database. One is the basic performance including the tensile elongation and so on. The other is the use of Performance and service performance. Such performance is mainly provided to the OEM for forward design. It is used for the whole process development phase of the vehicle concept / engineering design and process lightweight mold development. It can be provided to the OEM, and it is also shared with the OEM. do research. The reverse analysis database includes material analysis, process analysis, and 3D scanning, etc., for the reverse design of the car.
In addition, the lightweight application technology has its own dedicated user technology laboratory, the molding laboratory has universal forming testing machines, three-point bending, fatigue testing machines and other equipment; the welding laboratory includes laser welding, spot welding, carbon dioxide protection welding, etc. Equipment; coating equipment includes phosphating, electrochemical workstation, weather resistance, salt spray, etc. In addition, the simulation is still very important for material design. We build our own simulation platforms, including Tangshan Iron and Steel, Handan Iron & Steel, Steel Research Institute, etc. We borrow the simulation technology resources of third-party cooperation platforms, including Tianjin National Supercomputing Center, Yanshan University, University of Queensland, etc.
In the field of applied technology, we mainly develop roll forming, mainly do research on the rolling performance of materials, as well as process optimization and cross-section optimization, and quality and safety evaluation of part forming. Because rolling will make a lot of light-weight formed materials, there will be some difficulties. After 1180 to 1500 MPa, there will be some product defects that are difficult to guarantee. For example, it is difficult to achieve accuracy when the slide rails are relatively high, because when making many parts, It is necessary to repeatedly bend 20 and 30 vehicles, making the performance of the formed parts difficult to guarantee. We have developed a chain mold forming in cooperation with the University of Queensland. The diameter of this roller can be 20-30 meters. The forming deformation area can reach about 700-800 mm, which makes the entire forming process very slow. This reduces the process of excess stress and strain, and the forming quality and accuracy of the material has also been greatly improved.
The service safety evaluation section mainly detects high-speed stress-strain curves, studies strain-strength and strain-rate-sensitive curve models, and provides them to the OEM. After high-speed stretching, the fracture state of the fracture and nearby tissues will be checked to see if the material is high After that, will the material fail abnormally, which will affect the safety performance of the collision and also prove whether the material is safe during the collision? It is verified through simulation that our model meets the requirements of energy absorption for intrusion performance.
The service cases of new energy vehicles are mainly hot formed steel and roll forming and cold stamping. The second service case is the service case on the new energy bus. This was done early. At the time, it was an ordinary new energy bus. The mileage was 300 kilometers. At the beginning of Q345, we used Hegang's materials to achieve this. Lightweight design. Material selection design was carried out using our materials 780 and 980. We optimized the shape of the structure and then carried out a simple design. It was finally determined that the internal structure reached 4 mm, which was originally 1.5 mm, which also met his requirements. Some adjustments have been made accordingly.
Welding this piece also provides many welding solutions, because the welding wire of high-strength steel is more difficult to choose, and the window is provided to them to meet the requirements through monitoring and performance. After simulation, it still meets the requirements of passenger car collision.
This is a lightweight project for seats. The weight of the slide rail is 0.4KG, and the weight reduction ratio reaches 8.5%. After thinning, it is still difficult to form and weld. We use a chain die and roll forming process. The residual force inside will be very small. The non-deformed area will not form deformation and will not have quality defects. The residual force of the deformation is only 0.4-0.5 times the yield strength.
Looking at the development trend of automotive steel, automotive materials are still developing in a multi-material mixed direction. Automotive steel is still the main material, mainly cost and performance, in addition to the life-cycle carbon emissions, and the comparison of steel parts and components. Good repairability. There are four models of automotive materials, steel-based design, steel-aluminum hybrid, aluminum-based, and carbon fiber-based design. It can be seen that steel is irreplaceable in all models, and aluminum and carbon fiber-based design There is also about 15% -30% steel. The development of new steel grades, AHSS steel application technology, and multi-material composite application technology is the development trend of automotive steel.