Application of Rusty Steel in the Automobile Industry
In recent years, the automotive industry is developing towards high quality and light weight. How to reduce energy consumption as much as possible to achieve high operating capacity and low cost under rated traction power, that is, how to build green transportation equipment has become a society today. The topic of discussion.
In the automobile manufacturing industry, due to its high strength and relatively light weight, stainless steel materials, especially after being impacted, absorb energy stronger than other metal materials, have better safety performance, and are lighter in weight and longer service life compared with ordinary carbon steel vehicles. The advantages of simple manufacturing and assembly processes, etc., make the use of stainless steel in the automotive industry show a worldwide expansion trend, with a large potential market.
1. The development and application status of stainless steel in the automotive industry
The development of the stainless steel car body has mainly gone through four stages:
1) stainless steel car with stainless steel outer panel only;
2) semi-stainless steel car with carbon steel underframe;
3) all stainless steel cars;
4) lightweight stainless steel car.
The automotive industry is currently the fastest-growing stainless steel application field. In the past ten years, the consumption of stainless steel for automobiles in Japan has increased from an average of 10 kilograms to 30 kilograms, and the United States has exceeded 40 kilograms. Stainless steel is also widely used in public transportation vehicles such as buses, subways, and high-speed railway vehicles.
The Budd Company of the United States first used stainless steel in vehicle manufacturing in 1932 and developed the world’s first stainless steel railway passenger car. Japan and Germany used stainless steel and aluminum alloys in national railways and urban rail vehicles respectively.
Now, Japan, the United States, Sweden, and other countries have used a large number of stainless steel vehicles. Japan began to promote it in the 1980s, and currently, its stainless steel train cars have reached 60%. The car industry is the focus of the development of stainless steel applications.
The earliest production of stainless steel cars in my country was in 1987. A passenger car company in Changchun used 0Cr18Ni9 material and used traditional arc welding to produce stainless steel subway cars. Compared with the carbon steel car body, the stainless steel car body has been lightened by about 2 tons and has passed the static strength test, which indicates that my country has mastered the design and manufacture of lightweight stainless steel car bodies. In July 2003, my country’s first stainless steel urban rail passenger car with a speed of 100 km per hour was successfully rolled off the assembly line in Changchun. This was also my country’s first urban rail passenger car.
Before the 1990s, restricted by the economic development level at that time, various carbon steel vehicles were the main demand, and there was almost no demand for high-end vehicles such as stainless steel and aluminum alloy. After entering the 1990s, with the improvement of living standards and economic development, the market’s demand for high-end vehicles has greatly increased. The urban rail transit of Shanghai, Guangzhou, Wuhan and Chongqing uses aluminum alloy cars;
Tianjin Binhai Express Rail Transit uses stainless steel cars; Beijing hosts the 2008 Olympic Games, mainly using stainless steel cars; Qinghai-Tibet Railway considers using stainless steel passenger cars. At the end of this year, the Beijing Metro Line 15 vehicles will use the first domestically independently developed stainless steel metro vehicle products. The total number of vehicles on the entire line will reach 15 trains, two of which will be fully equipped trains.
The requirements of lightweight and high-grade development of rail vehicles will be the main development direction of rail vehicles in the future.
2. Development and application status of stainless steel materials for vehicles
Stainless steel not only has corrosion resistance but also has good physical properties and surface quality. It is widely used in automobile manufacturing. At present, there are mainly the following types of application parts.
1) The exhaust system uses stainless steel, most of which are ferritic stainless steel, which is the most used part of automotive stainless steel. Depending on the location of the exhaust system, component structure, gas temperature, and corrosive environment are quite different. Therefore, in addition to the high-temperature strength and high-temperature oxidation resistance of stainless steel materials, automobile exhaust systems also require high-temperature corrosion resistance and thermal fatigue properties. 409L, 436L, etc. are commonly used stainless steel grades.
2) Stainless steel for the automobile fuel tank. Coated plain carbon steel is generally the traditional steel for automobile fuel tanks, but fuel tanks made of stainless steel have no risk of fuel leakage, and have excellent corrosion resistance and good formability, and can omit or simplify the painting process, and are easy to recycle. 304L, JFE-SX1, etc. are commonly used stainless steel grades.
3) Stainless steel for automobile frame. The biggest feature of the combined frame made of stainless steel is its high rigidity. While ensuring a high enough weight ratio and strength, stainless steel also has good toughness, plasticity, formability, and weldability. The combination of the modular car frame design and the excellent performance of stainless steel materials can make a car with good impact resistance, light weight, high safety and reliability, and long life. In addition, such a frame can also be completely recycled. 409L, 3Cr12, 304L, etc. are all commonly used stainless steel grades.
4) Automobile stainless steel parts. There are mainly stainless steel sealing rings and heat exchangers. The sealing rings generally use 301 stainless steel, and the heat exchangers generally use stainless steel materials such as SUS304, SUS430, and SUS409L.
5) Stainless steel for automobile decoration. In addition to the functions they should have, some other exterior parts of the car also have decorative functions. Manufacturers use stainless steel moldings, antennas, wheel covers, etc. on small cars, and stainless steel on handrails, safety railings, and booms of large passenger cars and vehicles. In order to reduce costs, rearview mirrors are mainly made of SUS430J1L series stainless steel, and some luxury cars use SUS436J1L series stainless steel; car wipers mostly use SUS430, SUS304, SUS301, etc.; headlight guards use SUS430 and other steel grades.
Stainless steel is often used in safety devices in automobiles. For example, the seat belt tensioner is made of SUS301 stainless steel, the airbag sensors and booster pumps are mainly made of SUS304 and SUS304L stainless steel, and the ABS induction ring is made of SUS434, SUS444, and other steel grades.
With the continuous development of the automobile industry, the application of stainless steel in the automobile industry has become more and more extensive, and its importance in the manufacture of vehicle frames, exhaust systems, and engine parts has become increasingly prominent.
Automobile frame or automobile integral shell made of stainless steel containing 11% to 12% Cr, commonly used brands are 00Cr11Ti, 0Cr11Ni4Ti, 00Cr12NiTi, etc. Some countries have successively used stainless steel in large buses, coal transport vehicles, urban subway vehicles, etc. The actual use has proved that after operating 1.2 million kilometers, the exposed frame parts are still in good condition, and the exposed parts of the coating peeling off No signs of corrosion were seen, there was no part of the car protected by any coating, no rust was found, and the surface was intact.
From the point of view of economy and practicability, 0Cr11Ti ferritic stainless steel is often used in the exhaust system of some European and American countries. Japan basically uses 13Cr~17Cr ferritic stainless steel and its improved versions. It is also used in some parts. Use Cr-Ni austenitic stainless steel. The stainless steel used for auto parts is basically 0Cr18Ni9 and Cr17 type ferritic stainless steel.
The main stainless steel parts of automobiles mainly include cylinder seals and seat belt curling devices. The material grades are generally 1Cr17Ni7; 1Cr13, 0Cr18Ni9, 0Cr17Ni12Mo2, etc. are used for automobile tightening. Firmware; 0Cr17, 0Cr18Ni9 are used for oil cooler plate heat exchangers; 0Cr17 can generally be used for headlight guard rings, large passenger car handrails, safety railings, etc.
In Japan in the early 1990s, about 100,000 to 130,000 tons of stainless steel were used in the automobile industry every year. Stainless steel is used in the automobile industry. In addition to its own functions, stainless steel is also decorative, which increases the appreciation of the car.
If domestic stainless steel cars want to form batches and reduce costs, the key point is to solve the problem of localization of stainless steel car materials. Stainless steel cars in Japan, South Korea, and other countries all use austenitic high-strength cold-rolled stainless steel plates for vehicles. The chemical composition, mechanical properties, and surface patterns of this material have become standards. In 2011, my country successfully produced duplex stainless steel for important parts of railway passenger cars, which replaced imported products and has been successfully used in subway cars.
3. Conclusion
Currently, China does not have accurate statistics on the cost of stainless steel vehicles. According to relevant statistics in Japan, in terms of manufacturing costs, the manufacturing cost of aluminum alloy car bodies is much higher than that of stainless steel cars and carbon steel cars. The cost level of the stainless steel car body is slightly higher than that of the carbon steel car body. In terms of maintenance costs, stainless steel cars have the lowest maintenance costs.
From the perspective of light weight, the stainless steel body is slightly heavier than the aluminum alloy body. Comprehensively considering the costs of manufacturing, maintenance, and energy consumption, stainless steel cars are much lower than aluminum alloy cars and carbon steel cars, so stainless steel cars are the most economical vehicles and have great development prospects.