SUS304 vs. SUS409 stainless steel: Used for exhaust pipes
Dec 29, 2025
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When it comes to selecting the right stainless steel for automotive exhaust pipes, two of the most commonly considered materials are SUS304 and SUS409 stainless steel. Both materials offer unique properties that make them suitable for different applications, but understanding their differences is crucial when choosing the best material for your exhaust system.
What is SUS304 stainless steel?
SUS304 (also known as AISI 304) is the most commonly used austenitic stainless steel, known for its excellent corrosion resistance, strength, and formability. It contains 18% chromium and 8% nickel, which gives it high corrosion resistance and makes it suitable for various high-temperature applications. It is widely used in various industries, including automotive, food processing, and chemical industries, which require high corrosion resistance and strength.
What is SUS409 stainless steel?
SUS409 is a ferritic stainless steel composed of 10.5% to 11.75% chromium, with a lower nickel content than SUS304. It has good oxidation resistance and resistance to mild corrosion at high temperatures, but its corrosion resistance is not as good as SUS304. Due to its affordability and high-temperature resistance, SUS409 is commonly used in automotive exhaust systems. Although its corrosion resistance is not as good as SUS304, it performs well in environments with oxidation and mild corrosion.
Key Differences Between SUS304 and SUS409 Stainless Steel for Exhaust Pipes
| Property | SUS304 Stainless Steel | SUS409 Stainless Steel |
|---|---|---|
| Corrosion Resistance | Excellent corrosion resistance, especially in high-humidity and oxidizing environments. | Good corrosion resistance, but not as high as SUS304. |
| Heat Resistance | Excellent heat resistance, can withstand temperatures up to 870°C (1600°F). | Good heat resistance, withstands up to 850°C (1562°F). |
| Durability | Highly durable and long-lasting, ideal for harsh environments. | Durable, but better suited for less demanding applications. |
| Cost | Higher cost due to higher alloy content (nickel). | More affordable, often used for cost-sensitive applications. |
| Weldability | Easy to weld and form, suitable for complex shapes. | Easy to weld but may require more careful control of heat. |
| Applications | Exhaust systems, food processing, chemical industries. | Primarily used in automotive exhaust systems, mufflers, pipes. |
SUS304 vs. SUS409 Stainless Steel Exhaust Pipes：price
| Product | SUS304 Stainless Steel | SUS409 Stainless Steel |
|---|---|---|
| Exhaust Pipe (1.5" - 2") | $5.50 - $7.00 per kg | $3.20 - $4.50 per kg |
| Exhaust Pipe (2" - 4") | $5.80 - $7.20 per kg | $3.50 - $5.00 per kg |
| Custom Exhaust Pipe (Different Diameters) | $5.60 - $7.10 per kg | $3.30 - $4.80 per kg |
| Muffler & Exhaust Components | $6.00 - $7.50 per kg | $3.60 - $5.30 per kg |
Why choose SUS409 stainless steel as the exhaust pipe material?
SUS409 stainless steel is chosen as the exhaust pipe material because, while meeting the requirements for continuous high-temperature oxidation resistance at 600–750°C, its nickel-free composition provides a 15–25% cost advantage. This makes it far more cost-effective than austenitic stainless steels like 304 in applications requiring heat resistance, moderate corrosion resistance, and cost sensitivity, such as automotive exhaust systems (mufflers, catalytic converter housings).
GNEE is an ISO-certified exporter of 304 and 409 stainless steel pipes. We are a trusted distributor and supplier of ASTM A312 TP304 seamless pipes. Our ASTM A268 TP409 seamless pipes are tested according to international standards and specifications (such as DIN, JIS, EN, ASTM, etc.). We maintain large inventories in Asia, GCC countries, the Gulf region, the Middle East, and the UK, enabling us to supply to over 28 countries with comprehensive after-sales service and fast delivery.Email: sales@gneestainless.com
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