409 stainless steel is a ferritic stainless steel commonly used in machinery, construction and other projects. Due to the presence of austenite grains, the mechanical properties are greatly improved. And because of the addition of many alloying elements, the strength and hardness are also greatly improved.
409L stainless steel has excellent corrosion resistance, is suitable for extending the life of the car and the weight of the car, and as an environmentally friendly material that can be recycled and reused, major automobile manufacturers such as GM, Ford, Volkswagen, and DaimlerChrysler use stainless steel for exhaust systems 100%. . The automobile exhaust system treats the high-temperature, high-speed combustion exhaust gas generated by the automobile engine and discharges it to the outside of the vehicle. The main function of the exhaust system is to reduce vibration and noise, and after the exhaust gas is reburned, it is converted into a clean gas. The car exhaust system is the longest part of the car parts. The system is subject to extreme temperature changes (-20 to 850 C) and high-frequency, high-speed exhaust gas high-frequency vibration, and is the most varied and complex in the car. In the environment, the temperature limit of 409L can be (-20 ~ 650  C). Recently, due to the increasingly strict environmental protection standards for vehicle exhaust, increased driving in short-distance urban areas, and the spread of winter snow removers, the use standards of exhaust systems have become increasingly strict. From the Euro II-Euro IV standard, traditional steel cannot meet its requirements. Technical requirements, high-end motorcycle exhaust system has adopted 409L material. Each vehicle uses 409L stainless steel with a capacity of 35KGS-65KGS.

chemical composition
Chemical composition of 409L/S40903 stainless steel (mass fraction, %)
Standard steel No. C: 0.22; Cr: 11; Ti: 1 ; N ; Nb ; Ni ; Si ; Mn ; P ; S ;
US ASTM 409L/S40903 0.030 10.5~11.7 6× C~0.75 - 0.50 1.00 1.00 0.040 0.030 -
Grade comparison of 409L/S40903 stainless steel: international ISO X2CrTi12; European EN X2CrTi12/1.4512; Japan JIS SUH409L.
Characteristics of 409L/S40903 stainless steel
409L/S40903 steel is ultra-low carbon ferritic stainless steel with good oxidation resistance and good welding performance.

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