With the country's level of economic development and the increase in people's consumption, the consumption of stainless steel has shown a growing trend. The application of stainless steel in the automotive industry is one of the fastest growing application areas. The use of stainless steel casting with high strength, the body of the vehicle can greatly reduce the weight of the vehicle, enhance the strength of the paint structure with stainless steel for the vehicle panels and decorative parts can reduce maintenance costs, in addition, the use of stainless steel corrosion resistance and heat resistance advantages, applied to the exhaust system of the car. The automotive industry is the focus of the development of stainless steel applications.

Stainless steel not only has corrosion resistance, there are good physical properties and surface quality, in the automotive manufacturing is widely used, according to different parts of the automotive industry on the surface characteristics of stainless steel, mechanical properties and physical properties requirements are different, can be roughly grouped into five categories: automotive exhaust system with stainless steel, automotive fuel tank with stainless steel, automotive frame with stainless steel, automotive stainless steel parts and Automotive decorative stainless steel.

1, automotive exhaust system with stainless steel

With the performance of the car engine to improve the exhaust rules of the strict, the engine exhaust gas temperature is getting higher and higher, recently some car exhaust temperature has been as high as 900 ℃, and there is a high temperature (up to 950 ℃) tendency. In line with this, the automotive industry requires exhaust system components with excellent heat and corrosion resistance, but also requires as light as possible, and now has used heat-resistant cast steel and heat-resistant steel to replace the past cast steel and ordinary steel components. According to the different parts of the exhaust system, the gas temperature, the structure of the components and the corrosive environment are very different, therefore, in addition to requiring the manufacturing material to have high temperature oxidation resistance and high temperature strength, the automotive exhaust system also requires its thermal fatigue characteristics, high temperature corrosion resistance and other properties. Such as in the high-temperature parts near the engine, the required material characteristics are mainly high-temperature strength, thermal fatigue characteristics, oxidation resistance and resistance to high-temperature salt corrosion; and in the parts far from the engine, the material is required to have good resistance to salt and condensation corrosion; the end of the car body pipe material, in addition to the need for good corrosion resistance, but also beautiful.

The amount of stainless steel used in the exhaust system has accounted for more than half of the total application of stainless steel, 80% of which is ferritic stainless steel. 409L, 436L, etc. are common grades of stainless steel. From the point of view of economy and practicality, some European and American countries choose 0Cr11Ti type ferritic stainless steel exhaust system, Japan uses 13Cr-17Cr ferritic stainless steel and its improved type.

2, automotive fuel tank with stainless steel

Fuel tank is an important safety and functional parts of the car, fuel tank steel material must have a variety of excellent performance, including excellent stamping and forming performance, excellent welding performance, high corrosion resistance (internal fuel corrosion resistance and external corrosion resistance to harsh environments). Stainless steel is the alternative to coated plain carbon steel for automotive fuel tanks and is currently in use worldwide. In addition to being free from the risk of fuel leakage, fuel tanks made from stainless steel have excellent corrosion resistance and good formability, and have the advantage of eliminating or simplifying the painting process, as well as being easily recyclable.

JFE announced in July 2003 that it had successfully developed a high corrosion resistance and formability ferritic stainless steel 18Cr for use in automotive fuel tanks and other parts of the fuel system. -1.45Mo-Ti (trade name JFE-SX1). As its corrosion resistance is closer to SUS304 than other ferritic stainless steel, but also has excellent press forming performance, as the American Iron and Steel Institute (AISI) under the Steel Strategic Alliance for Fuel Tanks (SASFT) the only designated ferritic stainless steel.

3、Stainless steel for car frames

Stiffness is the biggest feature of the combined frame made of stainless steel, because stainless steel in ensuring a high enough strength, weight ratio, but also has good plasticity, toughness, formability and weldability. Combined car frame design and stainless steel materials, the combination of excellent performance, you can create a particularly light weight, good impact resistance, high safety and reliability and long life of the car, so the frame can also be fully recycled. Japanese stainless steel companies are working hard to research automotive high-strength stainless steel, containing 12% chromium stainless steel has been successfully applied to high-speed passenger cars. The use of AISI409 type ferritic stainless steel made of the whole body shell, the service life is generally 15 years to 20 years.

Foreign development of chromium containing 12% of the low-alloy double stabilization treatment of stainless steel, to overcome the shortcomings of poor processing performance, steel organization for ferrite and a small amount of martensite, good weldability, yield strength better than austenitic stainless steel, but the price is only half of austenitic stainless steel. At present, South Africa, the United Kingdom, Australia, Belgium and other countries have successively used 3Cr12 stainless steel manufacturing large buses, coal transport vehicles, urban underground vehicles and various specifications of the sweeper (including the airport's large sweeper, sprinklers and trailers, etc.), or the combination of 3Cr12 and 304L stainless steel use.

4, automotive stainless steel parts

Stainless steel is also widely used in a variety of components. Stainless steel seals as a representative of the metal seal has become the main alternative to traditional asbestos seals. Stainless steel as a substrate overlaid with rubber made of metal seals, stainless steel substrate more SUS301, with the advantages of high temperature, corrosion resistance and good elasticity. In addition, when the engine is working, a series of failures will occur due to the increase in oil temperature, decrease in oil viscosity and deterioration of oil quality. Historically, the automotive industry has used tubular heat exchangers to cool the oil. In order to improve the cooling efficiency, compact structure, some production enterprises to use stainless steel plate heat exchanger, the material more SUS304, SUS430 and SUS409L. in the automotive fasteners, although traditionally used to use low-alloy cold heading steel materials, but in the automotive engine system, transmission system in some parts of the very harsh environmental conditions, the use of stainless steel is not uncommon, and the amount The trend is rising. Automotive fasteners commonly used stainless steel SUS410, SUS304, SUS316, SUS430J1L, SUH660, etc.

5, automotive decorative stainless steel

The decorative materials inside and outside the car have a long history of stainless steel, and there is a growing trend to expand the use of the range. In order to make the appearance of the car beautiful, manufacturers use stainless steel inserts in cars, antennas, wheel covers, in large buses, vehicles, handrails, safety rails, hanging hands on the bar also use stainless steel. Some of the other external parts of the car in addition to the functions they should have, while also being given decorative features. In order to reduce costs, the rear-view mirror mainly uses SUS430J1L series stainless steel, part of the senior car rear-view mirror using SUS436J1L series stainless steel; car windscreen wipers using SUS430, SUS304, SUS301, etc.; headlamp guard ring using SUS430 and other steel types. The safety devices on the car also use stainless steel. For example, the seat belt tightener uses SUS301 stainless steel, the airbag sensor and booster pump mainly use SUS304 and SUS304L stainless steel, ABS induction ring using SUS434, SUS444 and other steel.

The automotive industry is currently one of the fastest growing areas of stainless steel applications, taking into account the cost of manufacturing, maintenance and energy consumption, stainless steel vehicles to be significantly lower than aluminum vehicles and carbon steel vehicles, is the most economical vehicles, with great prospects for development.