Transportation industry is an important industry in 13 industries downstream of stainless steel. It occupies more than 10% of the consumption structure of stainless steel, and automobile industry is an indispensable part of transportation industry. Therefore, it has an important influence on the supply-demand relationship of stainless steel.

　　Since the early 1970s, the usage of stainless steel in automobiles has increased significantly. Since the mid-1990s, the usage of stainless steel for each automobile has gradually increased from about 10 kg in the 1980s to 20-30 kg, while the usage of stainless steel for each automobile in the United States has averaged more than 40 kg. Stainless steel not only has corrosion resistance, but also has good physical properties and surface quality, so it is widely used in automobile manufacturing. According to the different application parts, it can be roughly divided into the following categories: stainless steel for exhaust system, stainless steel for fuel tank, stainless steel for frame, stainless steel for automobile parts and decoration.

　　The follows is the main usage of stainless steel in automotive field

　　1) exhaust system

　　Exhaust system is the most widely used component of automotive stainless steel, which accounts for more than half of the total application of automotive stainless steel, and 80% is ferritic stainless steel. 409L, 436L and so on are commonly used stainless steel grades. With the improvement of automotive engine performance, the temperature of exhaust gas is getting higher and higher. Therefore, the automotive industry requires the components of exhaust system to have excellent heat resistance and corrosion resistance, and also to meet the requirements of automotive lightweight. Ferritic stainless steel with low cost, good oxidation resistance and thermal fatigue properties is naturally popular, and the proportion of its use will further increase.

　　2) Fuel tank

　　Stainless steel fuel tank not only has no danger of fuel leakage, but also has excellent corrosion resistance and good formability. It can omit or simplify the painting process and is easy to recycle. Therefore, stainless steel is another important choice for automobile fuel tank besides plating plain carbon steel. Influenced by cost and stress corrosion problems, more and more stainless steel for fuel tank has changed from austenitic stainless steel (such as SUS304L) to ferritic stainless steel, such as JFE-SX1

　　3) Automotive Spare parts

　　Mainly stainless steel sealing rings, heat exchangers and fasteners. Stainless steel seals have become the main substitute products of traditional asbestos seals, mainly made of stainless steel as the base plate covered with rubber. Among them, stainless steel substrates mostly use SUS301, which has the advantages of high temperature resistance, corrosion resistance and good elasticity. In order to improve the cooling efficiency and compact structure, the stainless steel plate heat exchangers are mostly made of SUS304, SUS430 and SUS409L. Commonly used stainless steel fasteners are SUS410, SUS304, SUS316, SUS430J1L, SUH660, etc

　　Transportation industry is an important industry in 13 industries downstream of stainless steel. It occupies more than 10% of the consumption structure of stainless steel, and automobile industry is an indispensable part of transportation industry. Therefore, it has an important influence on the supply-demand relationship of stainless steel. Since the early 1970s, the usage of stainless steel in automobiles has increased significantly. Since the mid-1990s, the usage of stainless steel for each automobile has gradually increased from about 10 kg in the 1980s to 20-30 kg, while the usage of stainless steel for each automobile in the United States has averaged more than 40 kg. Stainless steel not only has corrosion resistance, but also has good physical properties and surface quality, so it is widely used in automobile manufacturing. According to the different application parts, it can be roughly divided into the following categories: stainless steel for exhaust system, stainless steel for fuel tank, stainless steel for frame, stainless steel for automobile parts and decoration. The follows is the main usage of stainless steel in automotive field 1) exhaust system Exhaust system is the most widely used component of automotive stainless steel, which accounts for more than half of the total application of automotive stainless steel, and 80% is ferritic stainless steel. 409L, 436L and so on are commonly used stainless steel grades. With the improvement of automotive engine performance, the temperature of exhaust gas is getting higher and higher. Therefore, the automotive industry requires the components of exhaust system to have excellent heat resistance and corrosion resistance, and also to meet the requirements of automotive lightweight. Ferritic stainless steel with low cost, good oxidation resistance and thermal fatigue properties is naturally popular, and the proportion of its use will further increase. 2) Fuel tank Stainless steel fuel tank not only has no danger of fuel leakage, but also has excellent corrosion resistance and good formability. It can omit or simplify the painting process and is easy to recycle. Therefore, stainless steel is another important choice for automobile fuel tank besides plating plain carbon steel. Influenced by cost and stress corrosion problems, more and more stainless steel for fuel tank has changed from austenitic stainless steel (such as SUS304L) to ferritic stainless steel, such as JFE-SX1 3) Automotive Spare parts Mainly stainless steel sealing rings, heat exchangers and fasteners. Stainless steel seals have become the main substitute products of traditional asbestos seals, mainly made of stainless steel as the base plate covered with rubber. Among them, stainless steel substrates mostly use SUS301, which has the advantages of high temperature resistance, corrosion resistance and good elasticity. In order to improve the cooling efficiency and compact structure, the stainless steel plate heat exchangers are mostly made of SUS304, SUS430 and SUS409L. Commonly used stainless steel fasteners are SUS410, SUS304, SUS316, SUS430J1L, SUH660, etc