AISI 409 / UNS S40900 (Ferritic) Stainless Steel
Chemistry, mechanical properties, physical properties, and practical selection notes for rolled AISI 409 products.
Performance & Use Notes
- Ferritic stainless commonly used in automotive exhaust; magnetic; moderate corrosion resistance.
- Often chosen for heat resistance and cost vs austenitic grades.
Data Tables
- Cr ferritic stainless commonly used in automotive exhaust; moderate corrosion resistance; magnetic.
| Chemical composition (wt%) | Limits |
|---|---|
| C | 0.08 max |
| Cr | 10.5–11.75 |
| Ti | 6xC min to 0.75 max |
| Mn | 1.00 max |
| Si | 1.00 max |
| P | 0.040 max |
| S | 0.020 max |
| Ni | 0.50 max |
| N | 0.030 max |
| Mechanical (annealed) | Requirements (min / max) |
|---|---|
| YS | 25 ksi min |
| UTS | 55 ksi min |
| Elongation | 20% min |
| Hardness | B89 max |
| Physical | Typical (RMP) |
|---|---|
| Density | 0.279 lb/in³ |
| Modulus | 32.0 x 10^6 psi |
| CTE (68–212°F) | 6.5 x 10^-6 /°F |
| Thermal conductivity | 13.2 Btu/ft·hr·°F |
| Specific heat | 0.11 Btu/lb·°F |
| Electrical resistivity | 24.8 microohm-in |
Values shown are typical/spec limits at room temperature unless noted; requirements vary by product form, size, and specification.
409 stainless steel from Source21 is a ferritic stainless steel grade engineered for durability oxidation resistance and cost efficiency in high temperature service. Originally developed for automotive exhaust systems Type 409 stainless steel provides dependable performance in environments where heat and corrosion resistance are required without the cost of higher alloyed stainless steels. It is commonly used in mufflers catalytic converter shells exhaust manifolds heat shields and industrial ducting where thermal stability and long term reliability are essential.
Source21 supplies 409 stainless steel in coil, strip, sheet, foil, and bar, all manufactured to meet ASTM A240 and ASTM A268 standards.
Contact the Source21 team to place an order review available forms or receive expert guidance for exhaust and heat resistant stainless steel applications backed by reliable supply and responsive service.