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What are the applications of stainless steel strips in automotive exhaust systems

source：www.19miao.com | Release time：2025年05月28日

In the exhaust system of automobiles, stainless steel strip has become the core material of key components due to its high temperature resistance, corrosion resistance, high strength, and good formability. The following are its main application scenarios and functional characteristics:
1、 Exhaust manifold and connecting pipe
1. Exhaust manifold
Function: Collect exhaust gases from each cylinder and introduce them into the exhaust pipe.
Material requirements: Must withstand high temperatures of 600-900 ℃ and corrosive gases (such as SO ? NOx）。
Application form:
The tubular structure is made of ferritic stainless steel strip (such as 409L, 430) or austenitic stainless steel strip (such as 304), and is formed by rolling and welding.
409L stainless steel strip is an economical choice due to its chromium (Cr ≈ 11%) and titanium (Ti) content, which balances corrosion resistance and high-temperature oxidation resistance; 304 stainless steel strip (Cr ≈ 18%, Ni ≈ 8%) has better corrosion resistance and is used for good car models.
Advantages: Compared to cast iron manifolds, it reduces weight by 30% -50% and significantly improves corrosion resistance, reducing the risk of rust and fracture.
2. Connecting pipe
Function: Connect the exhaust manifold with components such as catalytic converters and mufflers.
Material requirements: Must withstand vibration, high temperature (400-600 ℃), and exhaust gas erosion.
Application form:
409L stainless steel strip is rolled and welded into straight or corrugated pipes, and some models add flexible stainless steel strips (such as corrugated structures) to absorb engine vibration and avoid weld cracking.
2、 Catalytic converter (three-way catalyst)
1. Shell and carrier packaging
Function: Fixed catalytic carrier, capable of withstanding high temperatures of 800-1000 ℃ and exhaust gas corrosion.
Application form:
Shell: Stamped with austenitic stainless steel strips (such as 321, 316L) containing titanium (Ti) or niobium (Nb) elements to prevent intergranular corrosion and adapt to structural stability under long-term high temperature.
Carrier encapsulation layer: Made of high-temperature alloy stainless steel strip (such as Fe Cr Ni alloy) in a corrugated shape, it wraps around the catalytic ceramic carrier, uses the elasticity and high temperature resistance of the stainless steel strip to fix the carrier, and seals the exhaust gas.
3、 Silencer and tailpipe
1. Muffler housing
Function: Reduce exhaust noise through internal partitions and chambers.
Material requirements: It should be resistant to moisture and salt corrosion in exhaust gas (especially in winter snowmelt environments), and withstand vibration.
Application form:
The main body is made of 409L stainless steel strip rolled into a cylindrical shape, and the internal partition is made of 430 stainless steel strip stamped and assembled by laser welding or resistance welding.
Vehicle models or off-road vehicles may use 304 stainless steel strips to enhance corrosion resistance and surface glossiness.
2. Tail pipe
Function: Exhaust exhaust gas, while also serving as an exterior component that affects the overall appearance of the vehicle.
Application form:
The polished tail pipe is made of 304 stainless steel strip or 316 stainless steel strip, and the surface is treated with wire drawing and electroplating, which not only resists exhaust gas corrosion (containing H ? O, CO ?), but also enhances the visual texture.
Sports car models may use high-temperature resistant stainless steel strips (such as 429, 434), combined with materials such as carbon fiber, to balance performance and design.
4、 Other key components
1. Flanges and gaskets
Function: Connect various components of the exhaust system to ensure sealing.
Application form:
The flange is made of 409L stainless steel strip stamping, with nickel plating or heat-resistant coating sprayed on the surface to prevent corrosion at the bolt connection;
The gasket is made of thin stainless steel strip (such as 0.1-0.3mm thick 304 material) in a corrugated or toothed shape, utilizing the elasticity and corrosion resistance of stainless steel to enhance sealing reliability.
2. Thermal protection shield
Function: Isolate high temperatures in exhaust pipes, protect surrounding wiring harnesses and interior components.
Application form:
Made of 430 stainless steel strip or 409L stainless steel strip stamped into a wavy or honeycomb structure, with a reflective coating sprayed on the surface, capable of withstanding high temperatures above 500 ℃, while reducing weight through perforated design.
5、 Performance advantages of stainless steel strip
High temperature resistance:
Ferritic stainless steel strips (such as 409L) can withstand high temperatures of 600-800 ℃ for a long time, while austenitic stainless steel strips (such as 304) can reach temperatures above 900 ℃, meeting the temperature requirements of exhaust systems under all operating conditions.
Corrosion resistance:
The passivation film formed by chromium (Cr) element can resist the corrosion of sulfides and water vapor in exhaust gas. Nickel (Ni) and molybdenum (Mo) (such as 316L) further enhance the acid resistance and extend the service life of components (the service life of ordinary carbon steel components is about 5-8 years, and stainless steel components can reach 10-15 years).
Molding and weldability:
Stainless steel strip can be controlled in thickness (0.2-3mm) through cold rolling process, making it easy to punch and roll into complex shapes (such as corrugated pipes and irregular pipe fittings); Simultaneously supporting laser welding, argon arc welding and other processes, the welding joint has high strength and good sealing.
Lightweight:
Compared to cast iron or ordinary steel, stainless steel strip has a lower density (about 7.9g/cm 3), reduces component weight by 20% -40% under the same strength, and helps improve the fuel economy of the entire vehicle.

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