Application of 400 series stainless steel in automobile exhaust system

With the continuous advancement of 400 series stainless steel production technology, many types of stainless steel parts for automobiles are made of 400 series stainless steel materials, and exhaust systems are even more widely used. The following is an introduction to the use of component materials in the exhaust system.
Let’s talk about the exhaust manifold first. The stainless steel materials used to make the exhaust manifold include austenitic stainless steel and ferritic stainless steel. Austenitic stainless steel has better high-temperature strength, but because it is prone to oxide scale peeling, it is not as good as ferritic stainless steel in terms of oxidation resistance. Common steel types include 304 stainless steel and XM15J1 stainless steel.
In addition, ferritic stainless steel has better oxidation resistance, but because of its low thermal expansion coefficient, it is more advantageous in terms of thermal fatigue characteristics. The steel types used are 409L stainless steel and 430J1L stainless steel.
Nowadays, with the strengthening of exhaust gas emission regulations, the exhaust temperature is trending towards high temperatures, some as high as 950°C. In this case, 444 stainless steel can be used. In order to reduce material costs, some can also use 429 stainless steel with reduced chromium content. Exhaust manifolds using dual pipes usually use austenitic stainless steel for the inner pipe and ferritic stainless steel for the outer pipe.
Stainless steel materials used in automobile front tubes include ferritic stainless steels such as 409L, 436L and 430J1L. However, when using hollow double tubes, some also use austenitic stainless steel as the inner tube.
Most of the materials used in catalytic converters are 430 stainless steel. However, as the exhaust temperature increases, ferritic stainless steels with better high-temperature properties such as 430J1L or 429 are also used.
The material of the central tube used to be hot-dip aluminized steel plate. Because measures were taken to prevent moisture corrosion on the inside and outside of the tube, the use of stainless steel has increased significantly, mainly using 410 series stainless steel, 409L and 430 series stainless steel.
The main silencer is mainly made of 436L stainless steel.
Due to the low operating temperature of the end pipe, from the perspective of material performance, aluminized steel plates can meet the requirements. However, from the perspective of higher requirements, some also use highly ferritic stainless steel such as 409L and 430 series. , and some use austenitic 304 stainless steel.
Although it will take some time for fuel cell vehicle technology to be popularized in the future, current internal combustion vehicles still occupy a dominant position. In this case, purifying the exhaust gas emitted by the vehicle, reducing the weight of the vehicle body, reducing fuel costs and protecting the environment are the main goals of the vehicle. Production plants need to bear social responsibilities. In order to fulfill this responsibility, the characteristics of automotive materials will become higher and higher, and materials with better cost performance will be used. Among them, 400 series stainless steel is a suitable choice.