When selecting a stainless steel pipe for automotive exhaust systems, the two most commonly considered options are 409 and 304 stainless steel. Both have distinct strengths, but your choice should depend on performance requirements, environment, and budget.
SS 409 pipe is a ferritic stainless steel with ~11% chromium and added titanium for improved heat stability and weldability. It's magnetic, cost-effective, and widely used in automotive exhaust systems.
SS 304 round pipe is an austenitic stainless steel with ~18% chromium and 8% nickel, offering superior corrosion resistance and durability, especially in marine or high-moisture environments. However, it's more expensive and less thermally stable under exhaust temperatures.
| Element | 409 Stainless Steel (EN 1.4512 / AISI 409) | 304 Stainless Steel (EN 1.4301 / AISI 304) |
|---|---|---|
| C (Carbon) | ≤ 0.03% | ≤ 0.08% |
| Cr (Chromium) | 10.5 – 12.5% | 18.0 – 20.0% |
| Ni (Nickel) | ≤ 0.5% | 8.0 – 10.5% |
| Ti (Titanium) | Stabilized (≥6×C, ~0.15–0.75%) | - |
| Mn (Manganese) | ≤ 1.0% | ≤ 2.0% |
| Si (Silicon) | ≤ 1.0% | ≤ 1.0% |
| N (Nitrogen) | ≤ 0.03% | ≤ 0.10% |
| Property | 409 Stainless Steel | 304 Stainless Steel |
|---|---|---|
| Yield Strength (MPa) | ≥ 170 | ≥ 205 |
| Tensile Strength (MPa) | 380 – 550 | 520 – 750 |
| Elongation (A50, %) | ≥ 20 | ≥ 40 |
| Hardness (HBW) | ≤ 200 | ≤ 201 |
| Density (g/cm³) | ~7.75 | ~8.00 |
| Magnetic | Yes (ferritic) | No (austenitic, non-magnetic) |
| Weldability | Good (with Ti stabilization) | Excellent |
| High-temperature resistance | Good (≤ 750–800°C) | Excellent (≤ 870–925°C) |
Is 304 stainless steel good for exhaust?
Yes, 304 Cold Roll stainless steel pipe is excellent for exhaust systems, especially in coastal, humid, or salted road environments. It provides exceptional resistance to rust, pitting, and corrosion, and is often used in aftermarket or high-performance exhaust systems where longevity is critical.
Is 409 stainless steel good for exhaust?
Yes, 409Cold Roll stainless steel pipe is a standard material for automotive exhaust systems, especially in original equipment (OE) applications. It offers good high-temperature oxidation resistance (up to ~750–800°C), excellent weldability, and lower cost than 304. Though surface rust may form, it generally won't corrode through, making it a reliable and economical exhaust material.
tips：Choose 409 for cost-effective, OEM-standard exhaust systems. Use 304 where long-term corrosion resistance is critical (e.g., humid coastal climates).
Gnee supplies both 409 and 304 Stainless steel prefabricated pipe , with custom sizes, surface finish, and export packaging. Over 18 years of experience, and trusted by automotive OEMs in over 30 countries.
TP409 welded/seamless steel tubes, custom lengths and bends available
The surface can be processed into 2B, BA, mirror and other states.
With EN 10204 3.1 material certificate
With various surface treatments and further processing services (laser cutting, bending, stamping)
